WO2025087898A1

WO2025087898A1 - Spectrometer device for obtaining spectroscopic information on at least one object wherein the imaging plane of the imaging system is positioned at a distance from the illumination plane

Info

Publication number: WO2025087898A1
Application number: PCT/EP2024/079824
Authority: WO
Inventors: Tibor Peter Lehnert; Felix Schmidt; Henning ZIMMERMANN; Bridget Sheeran
Original assignee: TrinamiX GmbH
Current assignee: TrinamiX GmbH
Priority date: 2023-10-23
Filing date: 2024-10-22
Publication date: 2025-05-01
Anticipated expiration: 2026-04-23

Abstract

A spectrometer device (130) and a method for obtaining spectroscopic information on at least one object (110) are disclosed. The spectrometer device (130) comprises: - at least one light emitting element (132) configured for emitting illumination light (134) for illuminating the at least one object (110) in at least one illumination plane (136); - at least one imaging system (140), the imaging system (140) comprising at least one detector (142) configured for detecting detection light (144) from the object (110) and for generating at least one detector signal upon detecting the detection light (144), wherein the imaging system (140) further comprises at least one optical element (148) for guiding the detection light (144) onto the detector (142), wherein the imaging system (140) is configured for receiving the detection light (144) from at least one imaging plane; - at least one sample interface (160) configured for allowing the illumination light (134) to illuminate the object (110) and configured for allowing the detection light (144) from the object (110) to propagate to the imaging system (140), wherein the sample interface (160) is configured for defining a measurement pose of the spectrometer device (130) with respect to the object (110); wherein the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136).

Description

SPECTROMETER DEVICE FOR OBTAINING SPECTROSCOPIC INFORMATION ON AT LEAST ONE OBJECT WHEREIN THE IMAGING PLANE OF THE IMAGING SYSTEM IS POSITIONED AT A DISTANCE FROM THE ILLUMINATION PLANE

5 Technical Field

The invention relates to a spectrometer device for obtaining spectroscopic information on at least one object, a mobile device comprising said spectrometer and a method for obtaining spectroscopic information on at least one object. The method and devices according to the pre0 sent invention can, in general, be used for investigating or monitoring purposes, in particular in the infrared (IR) spectral region, especially in the near-infrared (NIR) spectral region, in various areas, such as daily life, security technology, gaming, traffic technology, production technology, photography such as digital photography or video photography for arts, documentation or technical purposes, safety technology, information technology, agriculture, crop protection, mainte5 nance, cosmetics, medical technology or in the sciences. However, other applications are also possible.

Background art 0 Spectrometer devices are known to be efficient tools for obtaining information on the spectral properties of an object, when emitting, irradiating, reflecting and/or absorbing light. Spectrometer devices, thus, may assist in analyzing samples or other tasks in which information on the spectral properties of an object is of interest. 5 EP 2 821 777 A1 describes a spectral characteristics measurement device which causes measurement light emitted from an object to be measured to enter a fixed mirror unit and a movable mirror unit and forms interference light of measurement light reflected by the fixed mirror unit and measurement light reflected by the movable mirror unit. At this time, a change of the intensity of the interference light of measurement light is obtained by moving the movable mirror unit, 0 and an interferogram of measurement light is acquired based on the change. At the same time, reference light of a narrow wavelength band included in a wavelength band of the measurement light is caused to enter the fixed mirror unit and the movable mirror unit, and interference light of the reference light reflected by the fixed mirror unit and the reference light reflected by the movable mirror unit is formed. At this time, the movable mirror unit is moved to correct the interfero5 gram of measurement light based on an amplitude of the change of the interference light of the reference light and based on a phase difference between measurement light, which is at the same wavelength as the reference light in the measurement light, and the reference light, and a spectrum of the measurement light is acquired based on the corrected interferogram. 0 WO 2023/009840 A1 discloses a spectral analyzer that can be used for biological sample detection. The spectral analyzer includes an optical window configured to receive a sample and a spectral sensor including a chassis having various component assembled thereon. Examples of components may include a light source, a light modulator, illumination and collection optical elements, a detector, and a processor. The spectral analyzer is configured to obtain spectral data representative of a spectrum of the sample using, for example, an artificial intelligence (Al) engine. The spectral analyzer further includes a thermal separator positioned between the light modulator and the light source.

WO 2023/161403 A1 describes an in-use calibration method for a spectrometer device. The method comprises: a) providing the at least one spectrometer device comprising at least one optical measurement element and at least one optical calibration element having different optical properties; b) providing at least one sample; c) performing at least two measurements using the spectrometer device, specifically at least two consecutive measurements, wherein one of the measurements is performed with the sample and one of the measurements is performed without the sample, i. wherein performing the measurement with the sample comprises illuminating a detector of the spectrometer device via an optical measurement path by using the optical measurement element, the optical measurement path comprising at least one reflection at the at least one sample, and II. wherein performing the measurement without the sample comprises illuminating the detector via an optical calibration path independent from the optical measurement path by using the optical calibration element, the optical calibration path comprising at least one interaction with the optical calibration element without an interaction with the sample and wherein the optical calibration path is arranged within the spectrometer device, specifically within a housing of the spectrometer device; d) generating by the at least one detector at least one first detector signal Sdi according to the measurement without the sample and at least one second detector signal Sd2 according to the measurement with the sample; e) deriving at least one calibrated optical property of the at least one sample from the first detector signal Sdi and the second detector signal S 2. Further, a spectrometer device configured for performing an in-use calibration method and various uses thereof are disclosed.

DE 10 2019 126038 A1 discloses a spectrometer device and a manufacturing method for a spectrometer device. The light paths from a light source to the sample and from the sample via an interferometer to a photodetector can be specifically structured using a base element.

Usually, for obtaining information on the spectral properties of the object, the object may be illuminated with illumination light in a manner that the object generates detection light. The received detection light may then be analyzed for obtaining the spectral properties of the object. In general, most objects or samples, such as tissue, food or plastic samples, show volume effects. Specifically, the illumination light may not be perfectly reflected on the surface of the object and may penetrate into the volume of the object. Reflections of light within a volume of an object are known as “Kubelka-Munk reflections”. Further, different objects may exhibit different light penetration depths depending on the properties of the material of the object. Usually, in spectroscopy, the reflection light may be collected with an angle 6_C, which is, in general, optimal only for a single reflection plane. Volume reflections at the object may be approximated with reflections at different sample reflection planes, specifically resulting in reduced light collection. For example, in case of ideal surface reflections, a light collection optic of the spectrometer device can be optimized to collect the detection light at a single angle Q_c (angle with respect to surface normal of the sample or sample interface). However, in case of volume reflections at the object, i.e. in case the illumination light is reflected at both the surface and the volume of the object, the signal throughput may be reduced and, thus, the light collection optic of the spectrometer device may collect less light compared to ideal surface reflections. Further, these effects may become larger if different illumination paths with different collection angles are considered. For example, fluctuations in spectra may be observed due to different sample reflection planes. Additionally, fluctuations and/or the signal loss may increase with increasing reflection angle 6_C.

Problem to be solved

It is therefore desirable to provide methods and devices, which at least partially address the above-mentioned technical challenges and at least substantially avoid the disadvantages of known methods and devices. Specifically, a spectrometer device and a method for obtaining spectroscopic information on at least one object shall be proposed which allow for accounting for variations of different light penetration depths in the object.

Summary

This problem is addressed by a spectrometer device for obtaining spectroscopic information on at least one object, a mobile device comprising said spectrometer and a method for obtaining spectroscopic information on at least one object, with the features of the independent claims. Advantageous embodiments which might be realized in an isolated fashion or in any arbitrary combinations are listed in the dependent claims as well as throughout the specification.

In a first aspect of the present invention, a spectrometer device for obtaining spectroscopic information on at least one object is disclosed.

The term “spectrometer device” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optical device configured for acquiring at least one item of spectral information on at least one object. Specifically, the at least one item of spectral information may refer to at least one optical property or optically measurable property which is determined as a function of a wavelength, e.g. for one or more different wavelengths. More specifically, the optical property or optically measurable property, as well as the at least one item of spectral information, may relate to at least one property characterizing at least one of a transmission, an absorption, a reflection and an emission of the at least one object, either by itself or after illumination with external light. The at least one optical property may be determined for one or more wavelengths. The spectrometer device specifically may form an apparatus which is capable of recording a signal intensity with respect to the corresponding wavelength of a spectrum or a partition thereof, such as a wavelength interval, wherein the signal intensity may, specifically, be provided as an electrical signal which may be used for further evaluation. The spectrometer device, as an example, may be or may comprise a device which allows for a measurement of at least one spectrum, e.g. for the measurement of a spectral flux, specifically as a function of a wavelength or detection wavelength. The spectrum may be acquired, as an example, in absolute units or in relative units, e.g. in relation to at least one reference measurement. Thus, as an example, the acquisition of the at least one spectrum specifically may be performed either for a measurement of the spectral flux (unit W/nm) or for a measurement of a spectrum relative to at least one reference material (unit 1 ), which may describe the property of a material, e.g., reflectance over wavelength. Additionally or alternatively, the reference measurement may be based on a reference light source, an optical reference path, a calculated reference signal, e.g. a calculated reference signal from literature, and/or on a reference device.

Specifically, the at least one spectrometer device may be a diffusive reflective spectrometer device configured for acquiring spectral information from the light which is diffusively reflected by the at least one object, e.g. at least one sample. Additionally or alternatively, the at least one spectrometer device may be or may comprise an absorption- and/or transmission spectrometer. In particular, measuring a spectrum with the spectrometer device may comprise measuring absorption in a transmission configuration. Specifically, the spectrometer device may be configured for measuring absorption in a transmission configuration. As outlined above, however, other types of spectrometer devices are also feasible.

The at least one spectrometer device, specifically and as will be outlined in further detail below, may comprise at least one light source which, as an example, may be at least one of a tunable light source, a light source having at least one fixed emission wavelength and a broadband light source. The spectrometer device, as will be outlined in further detail below, further comprises at least one detector configured for detecting light, such as light which is at least one of transmitted, reflected or emitted from the at least one object. The spectrometer device further may comprise, as will be outlined in further detail below, at least one wavelength-selective element, such as at least one of a grating, a prism and a filter, e.g. a length variable filter having varying transmission properties over its lateral extension. The wavelength-selective element may be used for separating incident light into a spectrum of constituent wavelength signals whose respective intensities are determined by employing a detector such as a detector having a detector array as described below in more detail.

The spectrometer device, specifically, may be a portable spectrometer device. The term “portable” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the property of at least one object of being moved by human force, such as by a single user. Specifically, the object characterized by the term “portable” may have a weight not exceeding 10 kg, specifically not exceeding 5 kg, more specifically not exceeding 1 kg or even not exceeding 500 g. Additionally or alternatively, the dimensions of the object characterized by the term “portable” may be such that the object extends by no more than 0.3 m into any dimension, specifically by no more than 0.2 m into any dimension. The object, specifically, may have a volume of no more than 0.03 m³, specifically of no more than 0.01 m³, more specifically no more than 0.001 m³ or even no more than 500 mm³. In particular, as an example, the portable spectrometer device may have dimensions of e.g.

10 mm by 10 mm by 5 mm. Specifically, the portable spectrometer device may be part of a mobile device or may be attachable to a mobile device, such as a notebook computer, a tablet, a cell phone, such as a smart phone, a smartwatch and/or a wearable computer, also referred to as “wearable”, e.g. a body borne computer such as a wrist band or a watch. In particular, the a weight of the spectrometer device, specifically the portable spectrometer device, may be in the range from 1 g to 100 g, more specifically in the range from 1 g to 10 g.

The term “spectroscopic information”, also referred to as “spectroscopic information” or as “item of spectral information” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an item of information, e.g. on at least one object and/or radiation emitted by at least one object, characterizing at least one optical property of the object, more specifically at least one item of information characterizing, e.g. qualifying and/or quantifying, at least one of a transmission, an absorption, a reflection and an emission of the at least one object. As an example, the at least one item of spectral information may comprise at least one intensity information, e.g. information on an intensity of light being at least one of transmitted, absorbed, reflected or emitted by the object, e.g. as a function of a wavelength or wavelength sub-range over one or more wavelengths, e.g. over a range of wavelengths. Specifically, the intensity information may correspond to or be derived from the signal intensity, specifically the electrical signal, recorded by the spectrometer device with respect to a wavelength or a range of wavelengths of the spectrum.

The spectrometer device specifically may be configured for acquiring at least one spectrum or at least a part of a spectrum of detection light propagating from the object to the spectrometer. The spectrum may describe the radiometric unit of spectral flux, e.g. given in units of watt per nanometer (W/nm), or other units, e.g. as a function of the wavelength of the detection light. Thus, the spectrum may describe the optical power of light, e.g. in the NIR spectral range, in a specific wavelength band. The spectrum may contain one or more optical variables as a function of the wavelength, e.g. the power spectral density, electric signals derived by optical measurements and the like. The spectrum may indicate, as an example, the power spectral density and/or the spectral flux of the object, e.g. of a sample, e.g. relative to a reference sample, such as a transmittance and/or a reflectance of the object, specifically of the sample.

The spectrum, as an example, may comprise at least one measurable optical variable or property of the detection light and/or of the object, specifically as a function of the illumination light and/or the detection light. As an example, the at least one measurable optical variable or property may comprise at least one at least one radiometric quantity, such as at least one of a spectral density, a power spectral density, a spectral flux, a radiant flux, a radiant intensity, a spectral radiant intensity, an irradiance, a spectral irradiance. Specifically, as an example, the spectrometer device, specifically the detector, may measure the irradiance in Watt per square meter (W/m²), more specifically the spectral irradiance in Watt per square meter per nanometer (W/m²/nm). Based on the measured quantity the spectral flux in Watt per nanometer (W/nm) and/or the radiant flux in Watt (W) may be determined, e.g. calculated, by taking into account an area of the detector.

The term “object” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary body, chosen from a living object and a nonliving object. Thus, as an example, the at least one object may comprise one or more articles and/or one or more parts of an article, wherein the at least one article or the at least one part thereof may comprise at least one component which may provide a spectrum suitable for investigations. Additionally or alternatively, the object may be or may comprise one or more living beings and/or one or more parts thereof, such as one or more body parts of a human being, e.g. a user, and/or an animal.

The spectrometer device comprises: at least one light emitting element configured for emitting illumination light for illuminating the at least one object in at least one illumination plane; at least one imaging system, the imaging system comprising at least one detector configured for detecting detection light from the object and for generating at least one detector signal upon detecting the detection light, wherein the imaging system further comprises at least one optical element for guiding the detection light onto the detector, wherein the imaging system is configured for receiving the detection light from at least one imaging plane; at least one sample interface configured for allowing the illumination light to illuminate the object and configured for allowing the detection light from the object to propagate to the imaging system, wherein the sample interface is configured for defining a measurement pose of the spectrometer device with respect to the object, specifically during a spectral measurement of the object.

The imaging plane of the imaging system is positioned at a distance from the illumination plane.

The term “light” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to electromagnetic radiation in one or more of the infrared, the visible and the ultraviolet spectral range. Herein, the term “ultraviolet spectral range”, generally, refers to electromagnetic radiation having a wavelength of 1 nm to 380 nm, preferably of 100 nm to 380 nm. Further, in partial accordance with standard ISO- 21348 in a valid version at the date of this document, the term “visible spectral range”, generally, refers to a spectral range of 380 nm to 760 nm. The term “infrared spectral range” (I R) generally refers to electromagnetic radiation of 760 nm to 1000 pm, wherein the range of 760 nm to 1 .5 pm is usually denominated as “near infrared spectral range” (NIR) while the range from 1 .5 pm to 15 pm is denoted as “mid infrared spectral range” (MidlR) and the range from 15 pm to 1000 pm as “far infrared spectral range” (FIR). Preferably, light used for the typical purposes of the present invention is light in the infrared (IR) spectral range, more preferred, in the near infrared (NIR) and/or the mid infrared spectral range (MidlR), especially the light having a wavelength of 1 pm to 5 pm, preferably of 1 pm to 3 pm. This is due to the fact that many material properties or properties on the chemical constitution of many objects may be derived from the near infrared spectral range. It shall be noted, however, that spectroscopy in other spectral ranges is also feasible and within the scope of the present invention.

The term “light emitting element” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device configured for generating or providing light in the sense of the above-mentioned definition. The light emitting element may comprise at least one illumination source configured for generating light in the sense of the above-mentioned definition. The light emitting element specifically may be or may comprise at least one electrical light source.

The light emitting element may comprise at least one element selected from the group consisting of: a thermal radiator, such as an incandescent lamp and/or a thermal infrared emitter; a laser, specifically a vertical cavity surface emitting laser (VCSEL), more specifically a laser emitting at least one wavelength in the infrared region; a light-emitting diode (LED), specifically a LED emitting light that is at least partially located in the infrared spectral range and/or a LED illuminating an luminescent material for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range; a micro-electromechanical systems (MEMS)-based thermal emitter.

In spectroscopy, various sources and paths of light are to be distinguished. In the context of the present invention, a nomenclature is used which, firstly, denotes light propagating from the light emitting element to the object as “illuminating light” or “illumination light”. Secondly, light propagating from the object to the detector is denoted as “detection light”. The detection light may comprise at least one of illumination light reflected by the object, illumination light scattered by the object, illumination light transmitted by the object, luminescence light generated by the object, e.g. phosphorescence or fluorescence light generated by the object after optical, electrical or acoustic excitation of the object by the illumination light or the like. Thus, the detection light may directly or indirectly be generated through the illumination of the object by the illumination light.

Consequently, the term “illuminate”, as used herein, is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of exposing at least one element to light.

The term “illumination plane” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary two-dimensional area comprising the illumination light. The illumination plane may specifically be or may comprise an illumination spot being defined by the illumination light. Specifically, the illumination plane may be or may comprise an illumination spot being defined by a beam of the illumination light illuminating the object. The illumination light may be focused in the illumination plane. For example, the illumination plane may comprise a focus plane of the light emitting element emitting the illumination light. The illumination plane may specifically coincide with at least one surface of the object.

For example, the light emitting element may comprise a light-emitting diode (LED), specifically a LED emitting light that is at least partially located in the infrared spectral range. Alternatively or in addition, the light emitting element may comprise a LED emitting light that is illuminating a luminescent material, specifically a phosphor, for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range.

The term “light-emitting diode”, or briefly “LED”, as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optoelectronic semiconductor device capable of emitting light when an electrical current flows through the device. The optoelectronic semiconductor device may be configured for generating the light due to various physical processes, including one or more of spontaneous emission, induced emission, decay of metastable excited states and the like. Thus, as an example, the light-emitting diode, may comprise one or more of: a light-emitting diode based on spontaneous emission of light, in particular an organic light emitting diode, a light-emitting diode based on superluminescence (sLED), or a laser diode (LD) In the following, without narrowing the possible embodiments of the light-emitting diode to any of the before-mentioned physical principles or setups, the abbreviation “LED” will be used for any type of light-emitting diode.

Specifically, the LED may comprise at least two layers of semiconductor material, wherein light may be generated at at least one interface between the at least two layers of semiconductor material, specifically due to a recombination of positive and negative electrical charges, e.g. due to electron-hole recombination. The at least two layers of semiconductor material may have differing electrical properties, such as at least one of the layers being an n-doped semiconductor material and at least one of the layers being a p-doped semiconductor material. Thus, as an example, the LED may comprise at least one pn-junction and/or at least one pin-set up. It shall be noted, however, that other device structures are feasible, too. The at least one semiconductor material may specifically be or may comprise at least one inorganic semiconducting material. It shall be noted, however, that organic semiconducting materials may be used additionally or alternatively.

Generally, the LED may convert electrical current into light, specifically light that is at least partially located in the infrared spectral range. Alternatively or in addition, LED may convert electrical current into light into primary light, more specifically into blue primary light. The LED, thus, specifically may be a blue LED. The LED may be configured for generating the primary light, particularly for the light-conversion in the phosphor, also referred to as the “pump light”. Thus, the LED may also be referred to as the “pump LED”. The LED specifically may comprise at least one LED chip and/or at least one LED die. Thus, the semiconductor element of the LED may comprise an LED bare chip.

The term “luminescence” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to the process of spontaneous emission of light by a substance not resulting from heat. Specifically, luminescence may refer to a cold-body radiation. More specifically, the luminescence may be initiated or excited by irradiation of light, in which case the luminescence is also referred to as “photoluminescence”. The property of a material being capable of performing luminescence, in the context of the present invention, is referred to by the adjective “luminescent”. The at least one luminescent material specifically may be a photoluminescent material, i.e. a material which is capable of emitting light after absorption of photons or excitation light. Specifically, the luminescent material may have a positive Stokes shift, which generally may refer to the fact that the secondary light is red-shifted with respect to the primary light.

The at least one luminescent material, thus, may form at least one converter, also referred to as a light converter, transforming primary light into secondary light having different spectral properties as compared to the primary light. Specifically, a spectral width of the secondary light may be larger than a spectral width of the primary light, and/or a center of emission of the secondary light may be shifted, specifically red-shifted, compared to the primary light. Specifically, the at least one luminescent material may have an absorption in the ultraviolet and/or blue spectral range and an emission in the near-infrared and/or infrared spectral range. Thus, generally, the luminescent material or converter may form at least one component of the phosphor LED converging primary light or pump light, specifically in the blue spectral range, into light having a longer wavelength, e.g. in the near-infrared or infrared spectral range.

The luminescent material, specifically, may, thus, form at least one converter or light converter. The luminescent material may form at least one of a converter platelet, a luminescent and specifically a fluorescent coating on the LED and phosphor coating on the LED. The luminescent material may, as an example, comprise one or more of the following materials: Cerium-doped YAG (YAG:Ce3+, or Y3AI5O12:Ce3+); rare-earth-doped Sialons; copper- and aluminium-doped zinc sulfide (ZnS:Cu,AI).

The LED and the luminescent material, together, may form a so-called “phosphor LED”. Consequently, the term “phosphor light-emitting diode”, or briefly “phosphor LED”, as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a combination of at least one light-emitting diode configured for generating primary light or pump light, and at least one luminescent material, also referred to as a “phosphor”, configured for light-conversion of the primary light generated by the light-emitting diode. The phosphor LED may form a packaged LED light source, including the LED die, e.g. a blue LED emitting blue pump light, as well as the phosphor, which, as an example, fully or partially coats the LED, which is, as an example, configured for converting the primary light or blue light into light having differing spectral properties, specifically into near-infrared light. Generally, the phosphor LED may be packaged in one housing or may be unpackaged. Thus, the LED and the at least one luminescent material for light-conversion of the primary light generated by the light-emitting diode may specifically be housed in a common housing. Alternatively, however, the LED may also be an unhoused or bare LED which may fully or partially be covered with the luminescent material, such as by disposing one or more layers of the luminescent material on the LED die. The phosphor LED, generally, may form an emitter or light source by itself.

The illumination light may specifically have a spectral range at least partially located in the nearinfrared spectral range, specifically in the spectral range from 1 to 3 pm, preferably from 1 .3 to 2.5 pm, more preferably from 1 .5 to 2.2 pm.

As outlined above, the spectrometer device comprises the at least one imaging system. The term “system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary set of interacting or interdependent components forming a whole. Specifically, the components of a system may be configured for interacting with each other in order to jointly fulfill at least one common function. The components of a system may be handled independently or may be coupled or connectable. The term “imaging system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a system comprising one or more optical components configured for imaging, specifically for at least one of interacting, transmitting, reflecting, absorbing and diffracting light, specifically the detection light.

The imaging system comprises the at least one detector. The verb “to detect” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a process of at least one of determining, measuring and monitoring at least one parameter, qualitatively and/or quantitatively, such as at least one of a physical parameter, a chemical parameter and a biological parameter. Specifically, the physical parameter may be or may comprise an electrical parameter. Consequently, the term “detector” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device configured for detecting, i.e. for at least one of determining, measuring and monitoring, at least one parameter, qualitatively and/or quantitatively, such as at least one of a physical parameter, a chemical parameter and a biological parameter. The at least one detector may be configured for generating at least one detector signal, more specifically at least one electrical detector signal, such as an analogue and/or a digital detector signal, the detector signal providing information on the at least one parameter measured by the detector. The detector signal may directly or indirectly be provided by the at least one detector to an evaluation unit of the spectrometer device, such that the at least one detector and the evaluation unit may be directly or indirectly connected. The detector signals may be used as a “raw” detector signal and/or may be processed or preprocessed before further used, e.g. by filtering and the like. Thus, the at least one detector may comprise at least one processing device and/or at least one preprocessing device, such as at least one of an amplifier, an analogue/digital converter, an electrical filter and a Fourier transformation.

The at least one detector may be configured for detecting light propagating from the object to the spectrometer device or more specifically to the at least one detector of the spectrometer device. The at least one detector may be configured for determining at least one optical parameter, such as an intensity and/or a power of light by which at least one sensitive area of the detector is irradiated. More specifically, the at least one detector may comprise at least one photosensitive element and/or at least one optical sensor, such as at least one of a photodiode, a photocell, a photosensitive resistor, a phototransistor, a thermophile sensor, a photoacoustic sensor, a pyroelectric sensor, a photomultiplier and a bolometer. The at least one detector, thus, may be configured for generating at least one detector signal, more specifically at least one electrical detector signal, in the above-mentioned sense, providing information on at least one optical parameter, such as the power and/or intensity of light by which the detector or a sensitive area of the detector is illuminated. The at least one detector may be a Lead Sulfide (PbS) detector.

The detector may comprise a plurality of photosensitive elements, wherein each of the photosensitive elements may be configured for generating at least one detector signal when detecting the detection light, wherein, for example, the plurality of detector signals may be used for deriving the spectral information. The plurality of photosensitive elements may be arranged in at least one of a one-dimensional array, specifically a linear array, and a two-dimensional array. The term “array” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a spatial arrangement of two or more photosensitive elements. The array may comprise, as an example, a series of optical sensors which may, preferably, be arranged in a single line as a one-dimensional matrix along the length of the length variable filter or in more than one line, especially in two, three, or four parallel lines, in form of a two-dimensional matrix, in particular, in order to receive most of the intensity of the incident light as possible. Thus, a number N of photosensitive elements in one direction may be higher compared to a number M of photosensitive elements in a further direction such that the one-dimensional 1 x N matrix or a rectangular two-dimensional M x N matrix may be obtained, wherein M < 10 and N > 10, preferably N > 20, more preferred N > 50. In addition, the matrixes may also be placed in a staggered arrangement.

The plurality of photosensitive elements may be sensitive to differing, specifically not overlapping, wavelength intervals. For example, a first photosensitive element may detect light within a first wavelength range and a second photosensitive element may detect light within a second wavelength range, wherein the first and the second wavelength range may be different from each other, particularly in a manner that wavelength ranges do not overlap. Additionally, further photosensitive elements may detect light within further wavelength ranges, wherein the further wavelength ranges may be different from each other and from the first and second wavelength ranges, particularly not overlapping.

As outlined above, the imaging system further comprises the at least one optical element. The term “optical element” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device configured for interacting with light in a pre-defined manner, e.g. such that the light changes one or more of a direction of propagation, a spectral composition or other optical properties. The optical element may be configured for changing a path of the detection light, specifically for directing the detection light onto the detector. Alternatively or additionally, the optical element may interact with the incident light by reflection, scatting, refraction, diffraction, double refraction, dispersion and/or absorption, in order to guide the detection light onto the detector. Alternatively or additionally, the optical element may modify an intensity, a spectral composition, an orientation, a phase, a polarization, a direction and/or a beam shape of the detection light.

The optical element may be selected from the group consisting of: a mirror, specifically a curved mirror and/or a freeform mirror; a lens, specifically a focusing lens; an aperture; an optical waveguide; an optical fiber; a grating; a waveplate; a prism; an active optical element such as a micro mirror array, a liquid crystal array and/or another type of spatial light modulator (SLM); a combination of at least one of the prior mentioned optical elements.

As outlined above, the imaging system is configured for receiving the detection light from the at least one imaging plane. The term “imaging plane” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary two-dimensional area of light collection. Specifically, the imaging plane may be defined by a field of view of the imaging system. The imaging system may specifically be configured for receiving the detection light emerging from the imaging plane. The imaging plane may be or may comprise a light collection plane of the imaging system. For example, the imaging plane may comprise, specifically may be, at least one focusing plane. The imaging system may be configured for receiving the detection light emerging from the focusing plane. The imaging system may be focused for the focusing plane. Specifically, the focusing plane may define a light collection plane of the imaging system for which a received light intensity is higher compared with any other light collection plane. Alternatively or additionally, the imaging plane of the imaging system may be different from the illumination plane. Alternatively or additionally, the imaging plane of the imaging system may be positioned at a distance from the illumination plane corresponding to a penetration depth of the illumination light in the object. For example, the imaging plane may be at least partially located in the object applied to the sample interface. The imaging plane may be positioned from the illumination plane by a distance in the range of 0.01 mm to 10 mm, specifically in the range of 0.1 mm to 1.0 mm, more specifically in the range of 0.2 mm to 0.5 mm, more specifically is 0.25 mm, particularly in a direction from the illumination plane to the object. For example, the object applied to the sample interface may be or may comprise a skin of a human being or an animal. In this case, the imaging plane may be located in the object at a distance of 0.25 mm, which specifically corresponds to a penetration depth of light in the infrared spectral range into the skin. The distance of the imaging plane from the illumination plane may specifically be optimized for each object having different material properties. Alternatively or additionally, the object applied to the sample interface may be or may comprise an inorganic material, such as textiles or plastics. In this case, the imaging plane may be located in the object at a distance in the range of 0.1 mm to 1 .0 mm, specifically of 0.25 mm, which specifically corresponds to a penetration depth of light in the infrared spectral range into the inorganic material.

For example, the optical element for guiding the detection light onto the detector may comprise at least one lens, specifically at least one focusing lens, having at least one focal length, wherein the lens may be arranged to focus the detection light on the detector. The term “lens” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optically transparent element having at least one curved surface, particularly a surface curved in a spherical manner. Incident light, specifically an incident light ray or light beam, may be bend at the at least one surface of the lens, particularly depending on at least one of: the refractive index of the lens, the wavelength of the incident radiation. The incident light, such as a light ray, may be bend towards a center of a light beam comprising the light ray. Alternatively, incident light, such as a light ray, may be away from a center of a light beam comprising the light ray. The lens may have a convex surface for collecting and/or a concave surface for dispersing the incident light. The lens may specifically be a focusing lens focusing the detection light onto the detector. The lens may be arranged such that the imaging plane of the imaging system is positioned at a distance from the illumination plane.

Alternatively or additionally, the optical element for guiding the detection light onto the detector may comprise at least one freeform mirror, wherein the freeform mirror may be arranged to reflect the detection light onto the detector. The term ‘Treeform mirror” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an optical mirror having a non-symmetric reflecting surface. The freeform mirror may have at least one focal length such that the imaging plane of the imaging system is positioned at a distance from the object illumination plane. The focal length may be in the range of 5 mm to 15 mm, specifically in the range of 10 mm to 15 mm, more specifically is 12 mm. However, in principle, other forms of mirrors are also feasible, such as plane or curved mirrors. The curved mirror surface may be curved such that the imaging plane of the imaging system is positioned at a distance from the object illumination plane.

Alternatively or additionally, the optical element for guiding the detection light onto the detector may comprise at least one aperture having at least aperture stop, wherein the aperture may be arranged in a beam path of the detection light. The term “aperture” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a hole or an opening in a stop for transmitting light, specifically the detection light onto the detector. The aperture may specifically have a round shape. The size of the hole or opening, e.g. a diameter of the hole, may define the aperture stop of the aperture. The aperture having the aperture stop may be arranged such that the imaging plane of the imaging system is positioned at a distance from the illumination plane.

The imaging system may be configured for receiving the detection light having an angular distribution 0_C (0_C) on the sample interface with a centroid angle of the angular distribution in the range of 0° to 90°, specifically in the range of 15° to 75°, more specifically in the range of 30° to 70°, more specifically in the range of 45° to 65°. The angle 0_C may specifically be an angle between a light ray of the detection light on the sample interface and a surface normal of the sample interface. With the reduction of the angle 0_C in the range of 15° to 75°, more specifically in the range of 30° to 70°, more specifically in the range of 45° to 65°, the fluctuation in the spectra may be reduced.

The imaging system may have at least one light detection area in the range of 1 to 100 mm², specifically of 5 to 55 mm², more specifically in the range of 5 to 20 mm², more specifically in the range of 10 to 15 mm². The light detection area may be an area of one or more of the optical element and the detector of the imaging system. By increasing the light detection area in the range of 1 to 100 mm², specifically of 5 to 55 mm², more specifically in the range of 5 to 20 mm², more specifically in the range of 10 to 15 mm², a signal intensity of the detection light at the detector may be increased.

The imaging system may be configured for receiving the detection light from at least one elliptic light collection profile in the imaging plane. The term “elliptic light collection profile” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a light collection area having a boundary in the form of an ellipse. Thus, the boundary of the light collection area may be described by a curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. With the elliptic light collection profile, the imaging system may be configured for receiving equal or almost constant light intensity from reflection planes of different height. The elliptic light collection profile may allow collecting the detection light under a certain angle light from different reflection planes. As outlined above, the spectrometer device comprises the at least one sample interface. The term “sample interface” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary surface, e.g. measurement surface, at which the object is intended to interact with the spectrometer device. The sample interface may be or may comprise a real measurement surface or an imaginary measurement surface. For interacting with the object, the spectrometer device may emit the illumination light, particularly in a manner that the object generates the detection light. In addition, the spectrometer device may receive the detection light. The sample interface may particularly define a measurement pose of the object relative to the spectrometer device to allow light interaction with the object as intended. Having the object in the measurement pose, particularly as defined by the sample interface, at least one of the receiving of the illumination light by the object and the generating of the detection light may be performed in a manner as intended, specifically such that the signal-to-noise ratio of the spectrometer device is minimized.

The term “measurement pose” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a relative position and/or orientation of the object relative to the spectrometer device, specifically to the sample interface, which is intended to be assumed during the spectral measurement, particularly to allow an interaction between the spectrometer device and the object as intended, such as intended by the setup and/or arrangement of the components of the spectrometer device.

The sample interface may be an abstract element and may not require a structural feature, such as when the sample interface is a region in the environment of the spectrometer device. Alternatively, a device window, particularly an outer surface of the device window, of a device that is further comprising the spectrometer device may be used as the sample interface. Further, the sample interface may comprise at least one spectrometer window. At least one contact surface of the spectrometer window may define the measurement pose of the spectrometer device with respect to the object, particularly wherein the contact surface may be configured for being in contact with the object during a spectral measurement. The spectrometer window may be configured for transmitting the detection light and the illumination light. The term “spectrometer window” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary optically transparent window of the spectrometer device. The spectrometer window may be disposed in the beam path of the illumination light and/or the detection light. Typically, the spectrometer window may have a transparency coefficient, also referred to as a transmittance coefficient, of above 90%, preferably above 95%, specifically for light in the relevant spectral range. Additionally, for light outside the relevant spectral range, the spectrometer window may have a transmittance coefficient of below 10%, preferably of below 5%. The relevant spectral range may comprise, as an example, the infrared spectral range. Additionally or alternatively, the spectrometer window may have a transmittance coefficient being dependent on the angle of incidence. For example, in the infrared spectral range, the transmittance coefficient may be above 99% for an angle of incidence in the range from 0° to 20°, wherein the transmittance coefficient may be above 98% for an angle of incidence in the range from 21 ° to 50°, wherein the transmittance coefficient may be above 92% for an angle of incidence in the range from 51° to 60°, wherein the transmittance coefficient may be above 80% for an angle of incidence in the range from 61° to 70°, wherein the transmittance coefficient may be above 50% for an angle of incidence in the range from 71 ° to 80°.

The spectrometer window may be arranged in a housing of the spectrometer device. Alternatively or in addition, the spectrometer window may form a closure of the spectrometer device. Particularly, the spectrometer window may comprise an outer surface that is, particularly directly, facing the outside of the spectrometer device. The outer surface of the spectrometer window may be in contact with a surrounding environment, particularly wherein the surrounding environment is not comprised and/or enclosed by the spectrometer device, such as by being enclosed by a housing of the spectrometer device. The spectrometer window may comprise an inner surface that is facing the inside of the spectrometer device. The outer surface may be opposite of the inner surface. The inner surface of the spectrometer window may be in contact with an enclosed environment within the spectrometer device, particularly wherein the enclosed environment within the spectrometer device is enclosed by the housing of the spectrometer device. The enclosed environment within the spectrometer device may comprise a component of the spectrometer device and/or a gas comprised by the spectrometer device, such as ambient air, specifically dried ambient air being dried via a drying cartridge or a gel, and/or nitrogen and/or noble gases. The outer surface may be configured for being in contact with the object during the spectral measurement and, thereby, being used as the sample interface.

The spectrometer device may further comprise at least one wavelength-selective element for selectively transmitting light within at least one wavelength range. The term “wavelength-selective element” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary optical element which interacts with differing spectral portions of incident light in a different manner, e.g. by having at least one wavelength-dependent optical property, such as at least one wavelength-dependent optical property selected from the list consisting of a degree of reflection, a direction of reflection, a degree of refraction, a direction of refraction, an absorption, a transmission, an index of refraction. The wavelength-selective element may be disposed in at least one of a beam path of the illumination light and a beam path of the detection light.

The wavelength-selective element may comprise at least one of a tunable wavelength-selective element and a wavelength-selective element having a fixed transmission spectrum. The wave- length-selective element may be configured such that each of the photosensitive detectors may be exposed to the same spectral range of the detection light or to different, specifically nonoverlapping, spectral ranges of the detection light. By using a tunable wavelength selective element, as an example, differing wavelength ranges may be selected sequentially, whereas, by using a wavelength-selective element having a fixed transmission spectrum, the selection of the wavelength ranges may be fixed and may, however, be dependent e.g. on a detection position, thereby allowing, as an example, in the detection light beam path, for simultaneously exposing different detectors and/or different photosensitive detectors of the detector to differing spectral ranges of light.

The wavelength-selective element may comprise at least one element selected from the group consisting of: an optical filter; a bandpass filter; a length variable filter; a static filter; a tunable filter, specifically a MEMS Fabry-Perot cavity; an optical lens; a diffractive element; a grating; a prism; a plasmonic filter; a metamaterial. The wavelength-selective element may comprise one or more of a dispersive (e.g. prism), or diffractive (grating) element, or a detector with an inherently limited bandwidth of its spectral response. More specifically, the spectrometer device may comprise at least one filter element disposed in a beam path of the light from the object, i.e. in the beam path of the detection light, wherein the filter element, specifically may be configured such that each of the photosensitive elements is exposed to an individual spectral range of the light from the object. As an example, a variable filter element may be used, the transmission of which depends on a position on the filter element, such that, when the variable filter element is placed on top of the array of photosensitive elements, the individual photosensitive elements are exposed to differing spectral ranges of the incident light, specifically the detection light from the object. Additionally or alternatively the at least one wavelength-selective element may comprise at least one of the following elements: an array of individual bandpass filters, an array of patterned filters, a MEMS-lnterferometer, a MEMS-Fabry Perot interferometer. Further elements are feasible.

As outlined above, the detector may comprise a plurality of photosensitive elements, e.g. a plurality of photosensitive elements arranged in an array. The wavelength-selective element may be configured for selectively transmitting light such that at least two photosensitive elements of the plurality of photosensitive elements are exposed to individual, specifically deviating, wavelength ranges of the detection light from the object. For example, the wavelength-selective element may comprise a plurality of bandpass filters, wherein each bandpass filter may be arranged in a field of view of a specific photosensitive element. Each bandpass filter may be configured for selectively transmitting at least one wavelength range of the incident light, specifically incident detection light. The wavelength ranges of the bandpass filters may specifically different from each other, more specifically may be non-overlapping wavelength ranges.

The spectrometer device may further comprise at least one evaluation unit for evaluating the at least one detector signal generated by the detector and for deriving the spectroscopic information on the object from the detector signal. The term “to evaluate” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a process of processing at least one first item of information in order to generate at least one second item of information thereby. Consequently, the term “evaluation unit” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary device or a combination of devices configured to evaluate or process at least one first item of information, in order to generate at least one second item of information thereof. Thus, specifically, the evaluation unit may be configured for processing at least one input signal and to generate at least one output signal thereof. The at least one input signal, as an example, may comprise at least one detector signal provided directly or indirectly by the detector, specifically the plurality of detector signals from the plurality of photosensitive elements.

As an example, the evaluation unit may be or may comprise one or more integrated circuits, such as one or more application-specific integrated circuits (ASICs), and/or one or more data processing devices, such as one or more of computers, digital signal processors (DSP), field programmable gate arrays (FPGA) preferably one or more microcomputers and/or microcontrollers. Additional components may be comprised, such as one or more preprocessing devices and/or data acquisition devices, such as one or more devices for receiving and/or preprocessing of the detector signals, such as one or more AD-converters and/or one or more filters. Further, the evaluation unit may comprise one or more data storage devices. Further, the evaluation unit may comprise one or more interfaces, such as one or more wireless interfaces and/or one or more wire-bound interfaces.

The evaluation unit may be adapted to execute at least one computer program, such as at least one computer program performing or supporting the step of generating the items of information. As an example, one or more algorithms may be implemented which, by using the at least one detector signal may perform a predetermined transformation for deriving the spectroscopic information on the object, such as for deriving a corrected spectrum and/or for deriving at least one spectroscopic information describing at least one property of the object. For this purpose, the evaluation unit may, particularly, comprise at least one data processing device, also referred to as a processor, in particular an electronic data processing device, which can be designed to generate the desired information by evaluating the detector signal. The evaluation unit may use an arbitrary process for generating the required information, such as by calculation and/or using at least one stored and/or known relationship. The evaluation unit specifically may be configured for performing at least one digital signal processing (DSP) technique on the primary detector signal or any secondary detector signal derived thereof, in particular at least one Fourier transformation. Additionally or alternatively, the evaluation unit may be configured for performing one or more further digital signal processing techniques on the primary detector signal or any secondary detector signal derived thereof, e.g. windowing, filtering, Goertzel algorithm, crosscorrelation and autocorrelation. Besides the detector signal, one or a plurality of further parameters and/or items of information can influence said relationship. The relationship can be determined or determinable empirically, analytically or else semi-empirically. As an example, the relationship may comprise at least one of a model or calibration curve, at least one set of calibration curves, at least one function or a combination of the possibilities mentioned. One or a plurality of calibration curves can be stored for example in the form of a set of values and the associated function values thereof, for example in a data storage device and/or a table. Alternatively or additionally, however, the at least one calibration curve can also be stored for example in parameterized form and/or as a functional equation. Separate relationships for processing the detector signals into the items of information may be used. Alternatively, at least one combined relationship for processing the detector signals is feasible. Various possibilities are conceivable and can also be combined.

In a further aspect of the present invention, a mobile device, specifically a mobile communication device, is disclosed, comprising at least one spectrometer device according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below.

The term “mobile device” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a mobile electronics device, more specifically to a mobile communication device, such as a cell phone, a smartphone or a wearable. Additionally or alternatively, the mobile device may also refer to a tablet computer or another type of portable computer. The mobile device may be configured for providing access to at least one telecommunication network, such as a cell phone, a smartphone or a wearable. The mobile device may be a portable device in the sense of the above-mentioned definition.

In a further aspect of the present invention, a method for obtaining spectroscopic information on at least one object is disclosed. The method comprises the following steps that may be performed in the given order. However, a different order may also be possible. In particular, one, more than one or even all of the meth-od steps may be performed once or repeatedly. Further, the method steps may be performed successively or, alternatively, one or more of the method steps may be performed in a timely overlapping fashion or even in a parallel fashion and/or in a combined fashion. The method may further comprise additional method steps that are not listed.

The method comprises: a) providing at least one spectrometer device according to the present invention, such as according to any one of the embodiments disclosed above and/or according to any one of the embodiments disclosed in further detail below; b) illuminating, by using the light emitting element, the at least one object with illumination light; c) detecting, by using the detector of the imaging system, detection light from the object and generating at least one detector signal.

As outlined above, the spectrometer device may further comprise at least one evaluation unit. The method may further comprise evaluating, by using the evaluation unit, the at least one detector signal generated by the detector and deriving the spectroscopic information on the object from the detector signal. The method, specifically at least step c. of the method, may be computer-implemented or at least computer-controlled. The term “computer-implemented” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a process which is fully or partially implemented by using a data processing means, such as data processing means comprising at least one processing unit. The method, specifically step c., may be computer-implemented, or at least computer-controlled or computer-assisted, by using the evaluation unit of the spectrometer device.

Further disclosed and proposed herein is a computer program including computer-executable instructions for performing and/or controlling the method according to the present invention in one or more of the embodiments enclosed herein when the program is executed on a computer or computer network, specifically on the evaluation unit of the spectrometer device. Specifically, the computer program may be stored on a computer-readable data carrier and/or on a computer-readable storage medium.

As used herein, the terms “computer-readable data carrier” and “computer-readable storage medium” specifically may refer to non-transitory data storage means, such as a hardware storage medium having stored thereon computer-executable instructions. The computer-readable data carrier or storage medium specifically may be or may comprise a storage medium such as a random-access memory (RAM) and/or a read-only memory (ROM).

Thus, specifically, one, more than one or even all of method steps a) to c) as indicated above may be performed and/or controlled by using a computer or a computer network, preferably by using a computer program, more preferably by using a computer program executed by the evaluation unit of the spectrometer device.

Further disclosed and proposed herein is a computer program product having program code means, in order to perform and/or control the method according to the present invention in one or more of the embodiments enclosed herein when the program is executed on a computer or computer network, specifically on the evaluation unit of the spectrometer device. Specifically, the program code means may be stored on a computer-readable data carrier and/or on a computer-readable storage medium.

Further disclosed and proposed herein is a data carrier having a data structure stored thereon, which, after loading into a computer or computer network, such as into a working memory or main memory of the computer or computer network, e.g. a working memory or a main memory of the evaluation unit of the spectrometer device, may execute and/or may control the spectrometer to execute the method according to one or more of the embodiments disclosed herein. Further disclosed and proposed herein is a computer program product with program code means stored on a machine-readable carrier, in order to perform and/or control the method according to one or more of the embodiments disclosed herein, when the program is executed on a computer or computer network, specifically on the evaluation unit of the spectrometer device. As used herein, a computer program product refers to the program as a tradable product. The product may generally exist in an arbitrary format, such as in a paper format, or on a computer- readable data carrier and/or on a computer-readable storage medium. Specifically, the computer program product may be distributed over a data network.

Finally, disclosed and proposed herein is a modulated data signal which contains instructions readable by a computer system or computer network, specifically by the evaluation unit of the spectrometer device, for performing and/or controlling the method according to one or more of the embodiments disclosed herein.

Referring to the computer-implemented aspects of the invention, one or more of the method steps or even all of the method steps of the method according to one or more of the embodiments disclosed herein may be performed and/or controlled by using a computer or computer network, specifically by using the evaluation unit of the spectrometer device. Thus, generally, any of the method steps including provision and/or manipulation of data may be performed by using a computer or computer network. Generally, these method steps may include any of the method steps, typically except for method steps requiring manual work, such as providing the samples and/or certain aspects of performing the actual measurements.

The spectrometer device and the method according to the present invention, in one or more of the above-mentioned embodiments and/or in one or more of the embodiments described in further detail below, provide a large number of advantages over known devices and methods of similar kind. Specifically, the spectrometer device according to the present invention may allow to decrease the system sensitivity to account for variations of different light penetration depths in the object by shifting the imaging plane into the object. Thus, the plane of light collection for the spectrometer device may be assumed to lie within the sample, which specifically may be referred to as an effective sample plane. The position of the effective sample plane may be shifted into the object, e.g. for an object comprising a skin of a human being or animal about 0.25 mm into the object. Additionally or alternatively, the spectrometer device may have a reduced light collection angle for the detection light. The reduction in the light collection angle may reduce the fluctuations in spectra obtained with the spectrometer device. Additionally or alternatively, the spectrometer device may have an elliptic light collection profile. The elliptic light collection profile may allow collecting the detection light under a certain angle from different reflection planes. Additionally or alternatively, the spectrometer device may have an increased light detection area. Specifically, the optical element, such as the mirror, may collect light at steeper angles, and the optical path of the imaging system may be optimized.

As used herein, the terms “have”, “comprise” or “include” or any arbitrary grammatical variations thereof are used in a non-exclusive way. Thus, these terms may both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present. As an example, the expressions “A has B”, “A comprises B” and “A includes B” may both refer to a situation in which, besides B, no other element is present in A (i.e. a situation in which A solely and exclusively consists of B) and to a situation in which, besides B, one or more further elements are present in entity A, such as element C, elements C and D or even further elements.

Further, it shall be noted that the terms “at least one”, “one or more” or similar expressions indicating that a feature or element may be present once or more than once typically are used only once when introducing the respective feature or element. In most cases, when referring to the respective feature or element, the expressions “at least one” or “one or more” are not repeated, nonwithstanding the fact that the respective feature or element may be present once or more than once.

Further, as used herein, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way. The invention may, as the skilled person will recognize, be performed by using alternative features. Similarly, features introduced by "in an embodiment of the invention" or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the invention, without any restrictions regarding the scope of the invention and without any restriction regarding the possibility of combining the features introduced in such way with other optional or non-optional features of the invention.

Summarizing and without excluding further possible embodiments, the following embodiments may be envisaged:

Embodiment 1 : A spectrometer device for obtaining spectroscopic information on at least one object, the spectrometer device comprising: at least one light emitting element configured for emitting illumination light for illuminating the at least one object in at least one illumination plane; at least one imaging system, the imaging system comprising at least one detector configured for detecting detection light from the object and for generating at least one detector signal upon detecting the detection light, wherein the imaging system further comprises at least one optical element for guiding the detection light onto the detector, wherein the imaging system is configured for receiving the detection light from at least one imaging plane; at least one sample interface configured for allowing the illumination light to illuminate the object and configured for allowing the detection light from the object to propagate to the imaging system, wherein the sample interface is configured for defining a measurement pose of the spectrometer device with respect to the object, specifically during a spectral measurement of the object; wherein the imaging plane of the imaging system is positioned at a distance from the illumination plane.

Embodiment 2: The spectrometer device according to the preceding embodiment, wherein the imaging plane of the imaging system is different from the illumination plane.

Embodiment 3: The spectrometer device according to any one of the preceding embodiments, wherein the imaging plane of the imaging system is positioned at a distance from the illumination plane corresponding to a penetration depth of the illumination light in the object.

Embodiment 4: The spectrometer device according to any one of the preceding embodiments, wherein the optical element is selected from the group consisting of: a mirror, specifically a curved mirror and/or a freeform mirror; a lens, specifically a focusing lens; an aperture; an optical waveguide; an optical fiber; a grating; a waveplate; a prism; an active optical element such as a micro mirror array, a liquid crystal array and/or another type of spatial light modulator (SLM); a combination of at least one of the prior mentioned optical elements.

Embodiment 5: The spectrometer device according to any one of the preceding embodiments, wherein the optical element for guiding the detection light onto the detector comprises at least one lens, specifically at least one focusing lens, having at least one focal length, wherein the lens is arranged to focus the detection light on the detector.

Embodiment 6: The spectrometer device according to the preceding embodiment, wherein the lens is arranged such that the imaging plane of the imaging system is positioned at a distance from the illumination plane.

Embodiment 7: The spectrometer device according to any one of the preceding embodiments, wherein the optical element for guiding the detection light onto the detector comprises at least one freeform mirror, wherein the freeform mirror is arranged to reflect the detection light onto the detector.

Embodiment 8: The spectrometer device according to the preceding embodiment, wherein the freeform mirror has at least one focal length such that the imaging plane of the imaging system is positioned at a distance from the illumination plane.

Embodiment 9: The spectrometer device according to any one of the two preceding embodiments, wherein the focal length is in the range of 5 mm to 15 mm, specifically in the range of 10 mm to 15 mm, more specifically is 12 mm. Embodiment 10: The spectrometer device according to any one of the preceding embodiments, wherein the optical element for guiding the detection light onto the detector comprises at least one aperture having at least aperture stop, wherein the aperture is arranged in a beam path of the detection light.

Embodiment 11 : The spectrometer device according to the preceding embodiment, wherein the aperture having the aperture stop is arranged such that the imaging plane of the imaging system is positioned at a distance from the illumination plane.

Embodiment 12: The spectrometer device according to any one of the preceding embodiments, wherein the imaging plane comprises, specifically is, at least one focusing plane, wherein the imaging system is configured for receiving the detection light emerging from the focusing plane.

Embodiment 13: The spectrometer device according to any one of the preceding embodiments, wherein the imaging plane is at least partially located in the object applied to the sample interface.

Embodiment 14: The spectrometer device according to any one of the preceding embodiments, wherein the imaging plane is positioned from the illumination plane by a distance in the range of 0.01 mm to 10 mm, specifically in the range of 0.1 mm to 1.0 mm, more specifically in the range of 0.2 mm to 0.5 mm, more specifically is 0.25 mm.

Embodiment 15: The spectrometer device according to any one of the preceding embodiments, wherein the imaging system is configured for receiving the detection light having an angular distribution 0_C (0_C) on the sample interface with a centroid angle of the angular distribution in the range of 0° to 90°, specifically in the range of 15° to 75°, more specifically in the range of 30° to 70°, more specifically in the range of 45° to 65°.

Embodiment 16: The spectrometer device according to any one of the preceding embodiments, wherein the imaging system has at least one light detection area in the range of 1 to 100 mm², specifically 5 to 55 mm², more specifically in the range of 5 to 20 mm², more specifically in the range of 10 to 15 mm².

Embodiment 17: The spectrometer device according to any one of the preceding embodiments, wherein the imaging system is configured for receiving the detection light from at least one elliptic light collection profile in the imaging plane.

Embodiment 18: The spectrometer device according to any one of the preceding embodiments, wherein the light emitting element comprises at least one element selected from the group consisting of: a thermal radiator; a laser, specifically a vertical cavity surface emitting laser (VCSEL), more specifically a laser emitting at least one wavelength in the infrared region; a light-emitting diode (LED), specifically a LED emitting light that is at least partially located in the infrared spectral range and/or a LED illuminating an luminescent material for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range; a micro-electromechanical systems (MEMS)-based thermal emitter.

Embodiment 19: The spectrometer device according to any one of the preceding embodiments, wherein the illumination light has a spectral range at least partially located in the near-infrared spectral range, specifically in the spectral range from 1 to 3 pm, preferably from 1 .3 to 2.5 pm, more preferably from 1 .5 to 2.2 pm.

Embodiment 20: The spectrometer device according to any one of the preceding embodiments, wherein the detector comprises a plurality of photosensitive elements, wherein each of the photosensitive elements is configured for generating at least one detector signal when detecting the detection light.

Embodiment 21 : The spectrometer device according to the preceding embodiment, wherein the plurality of photosensitive elements are arranged in at least one of a one-dimensional array, specifically a linear array, and a two-dimensional array.

Embodiment 22: The spectrometer device according to any one of the preceding embodiments, wherein the spectrometer device further comprises at least one wavelength-selective element for selectively transmitting light within at least one wavelength range, wherein the wavelength-selective element is disposed in at least one of a beam path of the illumination light and a beam path of the detection light.

Embodiment 23: The spectrometer device according to the preceding embodiment, wherein the wavelength-selective element comprises at least one of a tunable wavelength-selective element and a wavelength-selective element having a fixed transmission spectrum.

Embodiment 24: The spectrometer device according to any one of the two preceding embodiments, wherein the wavelength-selective element comprises at least one element selected from the group consisting of: an optical filter; a bandpass filter; a length variable filter; a static filter; a tunable filter, specifically a MEMS Fabry-Perot cavity; an optical lens; a diffractive element; a grating; a prism.

Embodiment 25: The spectrometer device according to any one of three preceding embodiments, wherein the detector comprises a plurality of photosensitive elements, wherein the wavelength-selective element is configured for selectively transmitting light such that at least two photosensitive elements of the plurality of photosensitive elements are exposed to individual, specifically deviating, wavelength ranges of the detection light from the object. Embodiment 26: The spectrometer device according to the preceding embodiment, wherein the wavelength-selective element comprises a plurality of bandpass filters, wherein each bandpass filter is arranged in a field of view of a specific photosensitive element, wherein each bandpass filter is configured for selectively transmitting at least one wavelength range of the incident light, specifically detection light.

Embodiment 27: The spectrometer device according to any one of the preceding embodiments, wherein the sample interface comprises at least one spectrometer window, wherein at least one contact surface of the spectrometer window defines the measurement pose of the spectrometer device with respect to the object, particularly wherein the contact surface is configured for being in contact with the object during a spectral measurement.

Embodiment 28: The spectrometer device according to any one of the preceding embodiments, further comprising at least one evaluation unit for evaluating the at least one detector signal generated by the detector and for deriving the spectroscopic information on the object from the detector signal.

Embodiment 29: A mobile device, specifically a mobile communication device, comprising at least one spectrometer device according to any one of the preceding embodiments.

Embodiment 30: A method for obtaining spectroscopic information on at least one object, the method comprising: a) providing at least one spectrometer device according to any one of the preceding embodiments referring to a spectrometer device; b) illuminating, by using the light emitting element, the at least one object with illumination light; c) detecting, by using the detector of the imaging system, detection light from the object and generating at least one detector signal.

Embodiment 31 : The method according to the preceding embodiment, wherein the spectrometer device further comprises at least one evaluation unit, wherein the method further comprises evaluating, by using the evaluation unit, the at least one detector signal generated by the detector and deriving the spectroscopic information on the object from the detector signal.

Short description of the Figures

Further optional features and embodiments will be disclosed in more detail in the subsequent description of embodiments, preferably in conjunction with the dependent claims. Therein, the respective optional features may be realized in an isolated fashion as well as in any arbitrary feasible combination, as the skilled person will realize. The scope of the invention is not re- stricted by the preferred embodiments. The embodiments are schematically depicted in the Figures. Therein, identical reference numbers in these Figures refer to identical or functionally comparable elements.

In the Figures:

Figure 1 shows contributions to reflected light from an object;

Figure 2 shows a dependency of an exemplary attenuation coefficient k of water on the wavelength;

Figure 3 shows a dependency of an exemplary recorded reflection spectrum on the angle at which detection light is received from the object;

Figure 4 shows an exemplary embodiment of a spectrometer device for obtaining spectroscopic information on at least one object in a schematic view;

Figure 5 shows a further exemplary embodiment of a spectrometer device for obtaining spectroscopic information on at least one object in a schematic view; and

Figure 6 shows a flow chart of a method for obtaining spectroscopic information on at least one object.

Detailed description of the embodiments

Figure 1 shows exemplarily three contributions to the light that is reflected from an object 110, particularly for an object being and/or comprising a biological tissue. Typically, the reflected light may comprise diffuse Fresnel reflected light (indicated by a light ray denote by reference number 112). Diffusive Fresnel reflected light is generated in a scattering process on a surface of the object 110, particularly on a rough surface of the object 110. Additionally, the reflected light may comprise specular Fresnel reflected light (indicated by a light ray denote by reference number 114). Specular Fresnel reflected light results from a mirror like behavior of the surface of the object 110. It does not contain absorption information on the object 110. Furthermore, the reflected light may comprise volume reflected light (indicated by light rays denote by reference number 116). Volume reflected light may be Kubelka-Munk reflected light, also referred to as sub-surface reflected light. Volume reflected light may combine refractive (indicated by reference number 118) and diffractive effects (indicated by reference number 120). Volume reflected light may be influenced by at least one of: a particle size; a structure; a shape; an extinction coefficient of object 110. Typically, the ratio between specular Fresnel reflected light and diffusive Fresnel reflected light may be given by a surface roughness of the object 110 relative to a wavelength of the reflected light. Typically light propagation in a medium may be described by a complex refractive index n = n + ik, wherein n is a refractive index of the object 110 and k is an extinction coefficient, also referred to as an attenuation coefficient, of the object 110. Particularly in absorption spectroscopy, the goal may be, typically, to determine and/or to distinguish at least one component of the object 110, such as a material of the object 110, via light absorption. Light absorption may be determined by the extinction coefficient k.

Fresnel reflection may occur at interfaces between two media i = 1,2, each having a different complex refractive index H,. For light incidence perpendicular to a surface, Fresnel reflection may be determined by using the following equation

The refractive index n and attenuation coefficient k may be coupled via the so called Kramers- Kronig relations. Typically, in the near-infrared region, the refractive index n may be much larger than the attenuation coefficient k. This is exemplarily shown in Figure 2, which shows an attenuation coefficient k (denoted by reference number 122) of water. On the horizontal axis 124, the wavelength in pm is depicted. On the vertical axis 126, the attenuation coefficient k is depicted. The attenuation coefficient k is around 0.0003 at a wavelength of 1450 nm. For comparison, the refraction index n of water is around 1.37 at a wavelength of 1450 nm. Consequently, Fresnel reflection may not be influenced by the extinction coefficient k and Fresnel reflections may not carry information about light absorption by the medium in the near-infrared. In contrast, in the mid-infrared region, extinction coefficients k are of the order of the refractive index n. Thus, Fresnel reflection may be strongly influenced by the extinction coefficient. This effect may be used in attenuated total reflection spectroscopy in the mid infrared.

The reflectance of light propagating through the object 110, such as it is the case for volume reflected light 116, may be derived by considering the absorption via the extinction coefficient k, which may be described by the Lambert- Beer law and/or the scattering of light on optical interfaces within the object 110, also known as Kubelka- Munk reflection or sub-surface reflection, which combines refractive and diffractive effects at the optical interfaces between components having different optical properties, e.g. the surface of pores, cells and/or blood vessels of a biological tissue.

The absorption and the scattering may determine the amount of reflected light generated by the object 110. As absorption may imprint spectral information into the reflected light, such as exemplarily described by the Lambert-Beer law, a reflection spectrum comprising volume reflected light may carry information on the composition of the object 110, such as the concentration of biomarkers in tissue.

Figure 3 shows a dependency of an exemplary recorded reflection spectrum on the angle at which detection light is received from the object 110. As can be seen in Figure 3, due to the in- terplay of volume reflection, specular Fresnel reflection and diffusive Fresnel reflection, a recorded reflection spectrum (denoted by reference number 123) may show a dependence on an angle at which detection light is received from the object 110. Alternatively or in addition, a recorded reflection spectrum may show a dependency on an angle at which illumination light impinges on the object 110 (not depicted in Figure 3). On the horizontal axis 125 of Figure 3, the wavelength is depicted in nm. On the vertical axis 127, the absorbance is depicted. The recorded reflection spectrum (denoted by reference number 123) is free of contributions of specular Fresnel reflected light.

The exemplary recorded reflection spectrum depicted in Figure 3 is polycaprolactam (PA6), also known as Perlon. The numbers in the legend 128 of Figure 3 refer to an angle at which detection light is received from the object 110 in respect to a surface normal of the object 110. The term “Ref’ denoted in the legend 128 indicates a measurement recorded by using an integration sphere.

Figure 4 shows an exemplary spectrometer device 130 for obtaining at least one item of spectral information on at least one object 110 in a schematic view. An exemplary mobile device 131 , e.g. a mobile communication device such as a cell phone, a smartphone or a wearable, comprises the exemplary spectrometer device 130.

The spectrometer device 130 comprises at least one light emitting element 132 configured for emitting illumination light 134 for illuminating the at least one object 110 in at least one illumination plane 136. As an example, the light emitting element 132 may comprise a LED emitting light that is illuminating a luminescent material, specifically a phosphor, for light-conversion of light generated by the LED, wherein the luminescent material generates converted light that is at least partly located in the near-infrared spectral range. The light emitting element 132 may specifically comprise a phosphor LED. The phosphor LED may form a packaged LED light source, including the LED die, e.g. a blue LED emitting blue pump light, as well as the phosphor, which, as an example, fully or partially coats the LED, which is, as an example, configured for converting the primary light or blue light into light having differing spectral properties, specifically into near-infrared light. However, other light emitting elements 132 are also feasible, such as at least one element selected from the group consisting of: a thermal radiator, such as an incandescent lamp and/or a thermal infrared emitter; a laser, specifically a vertical cavity surface emitting laser (VCSEL), more specifically a laser emitting at least one wavelength in the infrared region; a micro-electromechanical systems (MEMS)-based thermal emitter.

The illumination light 134 may have a spectral range at least partially located in the near-infra- red spectral range, specifically in the spectral range from 1 to 3 pm, preferably from 1.3 to 2.5 pm, more preferably from 1 .5 to 2.2 pm.

As shown in Figure 4, the light emitting element 132 may be configured for illuminating a defined illumination area on the object 110, which specifically defines the illumination plane 136. As an example, the spectrometer device 130 may comprise a further optical element 138 configured for directing the illumination light 134 of the light emitting element 132 towards the object 110. Particularly, thereby, the further optical element 138 may control the illumination area on the object 110.

The spectrometer device 130 further comprises at least one imaging system 140. The imaging system 140 comprises at least one detector 142 configured for detecting detection light 144 from the object 110 and for generating at least one detector signal upon detecting the detection light 144. In the exemplary embodiment of Figure 4, the detector 142 may comprise a plurality of photosensitive elements 146, wherein each of the photosensitive elements 146 may be configured for generating at least one detector signal when detecting the detection light 144, wherein, for example, the plurality of detector signals may be used for deriving the spectral information. The plurality of photosensitive elements 146 may be arranged in at least one of a one-dimensional array, specifically a linear array, and a two-dimensional array. The plurality of photosensitive elements 146 may be sensitive to differing, specifically not overlapping, wavelength intervals. For example, a first photosensitive element 146 may detect light within a first wavelength range and a second photosensitive element 146 may detect light within a second wavelength range, wherein the first and the second wavelength range may be different from each other, particularly in a manner that wavelength ranges do not overlap. Additionally, further photosensitive elements 146 may detect light within further wavelength ranges, wherein the further wavelength ranges may be different from each other and from the first and second wavelength ranges, particularly not overlapping.

The imaging system 140 further comprises at least one optical element 148 for guiding the detection light 144 onto the detector 142. The optical element 148 may be selected from the group consisting of: a mirror, specifically a curved mirror and/or a freeform mirror; a lens, specifically a focusing lens; an aperture; an optical waveguide; an optical fiber; a grating; a waveplate; a prism; an active optical element such as a micro mirror array, a liquid crystal array and/or another type of spatial light modulator (SLM); a combination of at least one of the prior mentioned optical elements. The imaging system 140 is configured for receiving the detection light 144 from at least one imaging plane (not shown in Figure 4). The imaging plane of the imaging system 140 is positioned at a distance from the illumination plane 136.

For example, the imaging plane may be at least partially located in the object 110 applied to the sample interface. The imaging plane may be positioned from the illumination plane 136 by a distance in the range of 0.01 mm to 10 mm, specifically in the range of 0.1 mm to 1.0 mm, more specifically in the range of 0.2 mm to 0.5 mm, more specifically is 0.25 mm, particularly in a direction from the illumination plane 136 to the object 110. For example, the object 110 applied to the sample interface may be or may comprise a skin of a human being or an animal. In this case, the imaging plane may be located in the object 110 at a distance of 0.25 mm, which specifically corresponds to a penetration depth of light in the infrared spectral range into the skin. The distance of the imaging plane from the illumination plane 136 may specifically be optimized for each object 110 having different material properties. As an example, the optical element 148 for guiding the detection light 144 onto the detector 142 may comprise at least one lens 150, specifically at least one focusing lens, having at least one focal length, wherein the lens 150 may be arranged to focus the detection light 144 on the detector 142. The lens 150 may be arranged such that the imaging plane of the imaging system 140 is positioned at a distance from the illumination plane 136.

Alternatively or additionally, as an example, the optical element 148 for guiding the detection light 144 onto the detector 142 may comprise at least one freeform mirror 152, wherein the freeform mirror 152 may be arranged to reflect the detection light 144 onto the detector 142. The freeform mirror may have at least one focal length such that the imaging plane of the imaging system 140 is positioned at a distance from the illumination plane 136. The focal length may be in the range of 5 mm to 15 mm, specifically in the range of 10 mm to 15 mm, more specifically is 12 mm.

Alternatively or additionally, as an example, the optical element 148 for guiding the detection light 144 onto the detector 142 may comprise at least one aperture 154 having at least aperture stop, wherein the aperture 154 may be arranged in a beam path of the detection light 144. The aperture 154 having the aperture stop may be arranged such that the imaging plane of the imaging system 140 is positioned at a distance from the illumination plane 136.

The spectrometer device 130 may further comprise at least one wavelength-selective element 156 for selectively transmitting light within at least one wavelength range. The wavelength-selective element 156 may be disposed in at least one of a beam path of the illumination light 134 and a beam path of the detection light 144. In this exemplary embodiment, as shown in Figure 4, the wavelength-selective element 156 may be configured for selectively transmitting light such that at least two photosensitive elements 146 of the plurality of photosensitive elements 146 are exposed to individual, specifically deviating, wavelength ranges of the detection light 144 from the object 110. For example, the wavelength-selective element 156 may comprise a plurality of bandpass filters 158, wherein each bandpass filter 158 may be arranged in a field of view of a specific photosensitive element 146. Each bandpass filter 158 may be configured for selectively transmitting at least one wavelength range of the incident light, specifically incident detection light 144. The wavelength ranges of the bandpass filters 158 may specifically different from each other, more specifically may be non-overlapping wavelength ranges.

The spectrometer device 130 further comprises at least one sample interface 160 configured for allowing the illumination light 134 to illuminate the object 110 and configured for allowing the detection light 144 from the object 110 to propagate to the imaging system 140, wherein the sample interface 160 is configured for defining a measurement pose of the spectrometer device 130 with respect to the object 110, specifically during a spectral measurement of the object 110. The sample interface 160 may comprise at least one spectrometer window 162. At least one contact surface of the spectrometer window 162 may define the measurement pose of the spectrometer device 130 with respect to the object 110, particularly wherein the contact surface may be configured for being in contact with the object 110 during a spectral measurement. The spectrometer window 162 may be configured for transmitting the detection light 144 and the illumination light 134.

Further, as shown in Figure 4, the spectrometer device 130 may comprise at least one evaluation unit 164 for evaluating the at least one detector signal generated by the detector 142 and for deriving the spectroscopic information on the object 110 from the detector signal.

Figure 5 shows a further exemplary embodiment of a spectrometer device 130 for obtaining spectroscopic information on at least one object 110 in a schematic view. The exemplary embodiment of the spectrometer device 130 of Figure 5 widely corresponds to the exemplary embodiment of the spectrometer device 130 shown in Figure 4. Thus, for a detailed description of the spectrometer device 130, reference is made to the description of Figure 4.

As can be seen in Figure 5, a center light ray 166 of a bundle of the illumination light 134 incident on the sample interface 160 may be parallel to a surface normal 168 of the sample interface 160 having the object 110 applied thereto. The imaging system 140 may receive the detection light 144 at an angle Q_c with respect to the surface normal 168 of the sample interface 160 (denoted by reference number 170). The imaging system 140 may be configured for receiving the detection light 144 having an angular distribution 0_C (0_C) on the sample interface 160 with a centroid angle of the angular distribution in the range of 0° to 90°, specifically in the range of 15° to 75°, more specifically in the range of 30° to 70°, more specifically in the range of 45° to 65°. With the reduction of the angle 0_C in the range of 15° to 75°, more specifically in the range of 30° to 70°, more specifically in the range of 45° to 65°, the fluctuation in the spectra may be reduced.

Figure 6 shows a flow chart of an exemplary method for obtaining spectroscopic information on at least one object 110. The method comprises using the spectrometer device 130 according to the present invention, such as according to any one of the embodiments shown in Figure 4 and 5 and/or according to any other embodiment disclosed herein. Thus, for a detailed description of the spectrometer device 130, reference is made to the description of Figures 4 and 5.

The method comprises the following steps that may be performed in the given order. However, a different order may also be possible. In particular, one, more than one or even all of the method steps may be performed once or repeatedly. Further, the method steps may be performed successively or, alternatively, one or more of the method steps may be performed in a timely overlapping fashion or even in a parallel fashion and/or in a combined fashion. The method may further comprise additional method steps that are not listed.

The method comprises: a) (denoted by reference number 172) providing at least one spectrometer device 130 according to the present invention; b) (denoted by reference number 174) illuminating, by using the light emitting element 132, the at least one object 110 with illumination light 134; c) (denoted by reference number 176) detecting, by using the detector 142 of the imaging system 140, detection light 144 from the object 110 and generating at least one detector signal.

As outlined above, the spectrometer device 130 may further comprise the at least one evaluation unit 164. The method may further comprise evaluating, by using the evaluation unit 164, the at least one detector signal generated by the detector 142 and deriving the spectroscopic infor- mation on the object 110 from the detector signal (denoted by reference number 178).

List of reference numbers object diffuse Fresnel reflected light specular Fresnel reflected light volume reflected light refractive effect diffractive effect attenuation coefficient k recorded reflection spectrum horizontal axis horizontal axis vertical axis vertical axis legend spectrometer device mobile device light emitting element illumination light illumination plane further optical element imaging system detector detection light photosensitive element optical element lens freeform mirror aperture wavelength-selective element bandpass filter sample interface spectrometer window evaluation unit center light ray surface normal angle 0_C providing at least one spectrometer device illuminating the at least one object detecting detection light evaluating the at least one detector signal

Claims

1 . A spectrometer device (130) for obtaining spectroscopic information on at least one object (110), the spectrometer device (130) comprising: at least one light emitting element (132) configured for emitting illumination light (134) for illuminating the at least one object (110) in at least one illumination plane (136); at least one imaging system (140), the imaging system (140) comprising at least one detector (142) configured for detecting detection light (144) from the object (110) and for generating at least one detector signal upon detecting the detection light (144), wherein the imaging system (140) further comprises at least one optical element (148) for guiding the detection light (144) onto the detector (142), wherein the imaging system (140) is configured for receiving the detection light (144) from at least one imaging plane; at least one sample interface (160) configured for allowing the illumination light (134) to illuminate the object (110) and configured for allowing the detection light (144) from the object (110) to propagate to the imaging system (140), wherein the sample interface (160) is configured for defining a measurement pose of the spectrometer device (130) with respect to the object (110); wherein the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136), wherein the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136) corresponding to a penetration depth of the illumination light (134) in the object (110).

2. The spectrometer device (130) according to the preceding claim, wherein the optical element (148) for guiding the detection light (144) onto the detector (142) comprises at least one lens (150) having at least one focal length, wherein the lens (150) is arranged to focus the detection light (144) on the detector (142), wherein the lens (150) is arranged such that the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136).

3. The spectrometer device (130) according to claim 1 , wherein the optical element (148) for guiding the detection light (144) onto the detector (142) comprises at least one freeform mirror (152), wherein the freeform mirror (152) is arranged to reflect the detection light (144) onto the detector (142), wherein the freeform mirror (152) surface has at least one focal length such that the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136).

4. The spectrometer device (130) according to claim 1 , wherein the optical element (148) for guiding the detection light (144) onto the detector (142) comprises at least one aperture (154) having at least aperture stop, wherein the aperture (154) is arranged in a beam path of the detection light (144), wherein the aperture (154) having the aperture stop is arranged such that the imaging plane of the imaging system (140) is positioned at a distance from the illumination plane (136).

5. The spectrometer device (130) according to any one of the preceding claims, wherein the imaging plane comprises at least one focusing plane, wherein the imaging system (140) is configured for receiving the detection light (144) emerging from the focusing plane, wherein the imaging system (140) is focused to the focusing plane, wherein the focusing plane defines a light collection plane of the imaging system (140) for which a received light intensity is higher compared with any other light collection plane.

6. The spectrometer device (130) according to any one of the preceding claims, wherein the imaging plane is at least partially located in the object (110) applied to the sample interface (160).

7. The spectrometer device (130) according to any one of the preceding claims, wherein the imaging plane is positioned from the illumination plane (136) by a distance in the range of 0.01 mm to 10 mm.

8. The spectrometer device (130) according to any one of the preceding claims, wherein the imaging system (140) is configured for receiving the detection light (144) having an angular distribution 0_C (0_C) on the sample interface (160) with a centroid angle of the angular distribution in the range of 0° to 90°.

9. The spectrometer device (130) according to any one of the preceding claims, wherein the imaging system (140) is configured for receiving the detection light (144) from at least one elliptic light collection profile in the imaging plane.

10. The spectrometer device (130) according to any one of the preceding claims, wherein the detector (142) comprises a plurality of photosensitive elements (146), wherein each of the photosensitive elements (146) is configured for generating at least one detector signal when detecting the detection light (144).

11 . The spectrometer device (130) according to any one of the preceding claims, wherein the spectrometer device (130) further comprises at least one wavelength-selective element (156) for selectively transmitting light within at least one wavelength range, wherein the wavelength-selective element (156) is disposed in at least one of a beam path of the illumination light (134) and a beam path of the detection light (144).

12. The spectrometer device (130) according to any one of the preceding claims, further comprising at least one evaluation unit (164) for evaluating the at least one detector signal generated by the detector (142) and for deriving the spectroscopic information on the object (110) from the detector signal.

13. A mobile device (131 ) comprising at least one spectrometer device (130) according to any one of the preceding claims.

14. A method for obtaining spectroscopic information on at least one object (110), the method comprising: a) providing at least one spectrometer device (130) according to any one of the preceding claims referring to a spectrometer device (130); b) illuminating, by using the light emitting element (132), the at least one object (110) with illumination light (134); c) detecting, by using the detector (142) of the imaging system (140), detection light (144) from the object (110) and generating at least one detector signal.

15. The method according to the preceding claim, wherein the spectrometer device (130) fur- ther comprises at least one evaluation unit (164), wherein the method further comprises evaluating, by using the evaluation unit (164), the at least one detector signal generated by the detector (142) and deriving the spectroscopic information on the object (110) from the detector signal.