WO2025115605A1 - Measurement device - Google Patents

Abstract

The present technology pertains to a measurement device capable of suitably measuring the spectrum of a measurement light. A measurement device according to the present technology is provided with: a luminous flux splitting unit for splitting substantially parallel luminous flux into a first luminous flux and a second luminous flux, refracting and emitting the first luminous flux, and emitting the second luminous flux in a direction symmetrical to the emission direction of the first luminous flux on the basis of a first reference plane that includes the traveling direction of the substantially parallel luminous flux, thereby causing the first luminous flux and the second luminous flux to interfere with each other; a light-condensing unit for condensing the first luminous flux and the second luminous flux on a second reference plane that includes the traveling direction of the substantially parallel luminous flux and is orthogonal to the first reference plane; a sensor unit for detecting interference light between the first luminous flux and the second luminous flux; and a calculation unit for calculating the spectrum of the substantially parallel luminous flux on the basis of a detection result by the sensor unit. The present technology can be applied to, for example, a spectroscopic measurement device.

Description

Measuring Equipment

This technology relates to a measurement device, and in particular to a measurement device that can optimally measure the spectrum of measurement light.

Spectroscopic measurements can provide a variety of information about the object being measured. The mid-infrared wavelength range of approximately 6 to 13 μm is also known as the molecular fingerprint region, where absorption due to various functional groups is observed. The mid-infrared wavelength range is used to identify and quantify the substances that make up the object being measured.

Spectrometers using a Michelson interferometer are widely used as devices for measuring absorption spectra in the mid-infrared range. However, because Michelson interferometer-based spectrometers have moving parts, they are not very robust and are not very portable. In addition, Michelson interferometer-based spectrometers require a certain amount of time for the mirror to scan in order to measure one spectrum, so they are not suitable for measuring moving samples or observing time responses to some kind of stimulus.

International Publication No. 2016/180551 International Publication No. 2014/054708

For example, Patent Document 1 describes a technology in which an incident light beam is split into two, one of which is phase-shifted and focused on a line sensor to generate interference fringes (interferograms) and perform Fourier spectroscopy. With the technology described in Patent Document 1, the light is first propagated to the side of the system by a beam splitter, which results in a large external size of the measuring device.

For example, in Patent Document 2, the wavefront of part of a nearly parallel light beam is tilted using an optical component called a phase shifter, and then the light beam is focused on a detection unit using a cylindrical lens. With the technology described in Patent Document 2, the light travels nearly on a single axis, and the use of a cylindrical lens makes it possible to focus the light beam over a short distance, thereby making it possible to miniaturize the entire measurement device.

However, with the technology described in Patent Document 2, the interference fringes are not vertical but tilted, so a line sensor cannot be used. Also, with the technology described in Patent Document 2, the actual interference fringes contain a bias component, so it is not possible to apply a large gain to the detection result by the detection unit, and the spectrum cannot be measured with high accuracy.

This technology was developed in consideration of these circumstances, and makes it possible to optimally measure the spectrum of the measurement light.

A measuring device according to one aspect of the present technology includes a beam splitting unit that splits a substantially parallel beam into a first beam and a second beam, refracts and emits the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to a first reference plane that includes the traveling direction of the substantially parallel beam, thereby causing interference between the first beam and the second beam, a focusing unit that focuses the first beam and the second beam on a second reference plane that includes the traveling direction of the substantially parallel beam and is perpendicular to the first reference plane, a sensor unit that detects interference light between the first beam and the second beam, and a calculation unit that calculates the spectrum of the substantially parallel beam based on the detection result by the sensor unit.

In one aspect of the present technology, a substantially parallel light beam is split into a first light beam and a second light beam, the first light beam is refracted and emitted, and the second light beam is emitted in a direction symmetrical to the emission direction of the first light beam with respect to a first reference plane including the traveling direction of the substantially parallel light beam. This causes the first light beam and the second light beam to interfere with each other, and the first light beam and the second light beam are focused on a second reference plane that includes the traveling direction of the substantially parallel light beam and is perpendicular to the first reference plane. The interference light between the first light beam and the second light beam is detected, and the spectrum of the substantially parallel light beam is calculated based on the detection result of the interference light.

1 is a diagram illustrating an example of the configuration of a spectroscopic measurement device according to a first embodiment of the present technology; 2A and 2B are a top view and a side view of the spectrometer of FIG. 1 . FIG. 13 is a diagram showing an example of interference fringes. FIG. 13 is a diagram showing an example of interference fringes compressed by a cylindrical lens. 1A and 1B are a top view and a side view showing an example of the configuration of a spectroscopic measurement device in which the functions of generating parallel light and dividing and refracting the parallel light are realized by a single member. 1A and 1B are a top view and a side view showing an example of the configuration of a spectroscopic measurement device in which the functions of splitting, refracting, and focusing parallel light are realized by a single member. FIG. 13 is a diagram showing an example of a slit. 11A and 11B are diagrams illustrating examples of arrangement of slit members. FIG. 2 is a diagram showing the appearance of a lens member. FIG. 4 is a diagram for explaining a lens member. 1A and 1B are a top view and a side view showing a configuration example of a spectroscopic measurement device when a lens member is provided. FIG. 2 is a diagram showing the appearance of a lens member. 1A and 1B are a top view and a side view of a spectrometer 1 in which a lens member and a cylindrical lens are integrated together. 1A and 1B are a top view and a side view of a spectroscopic measurement device in which a lens and a lens member are integrated. FIG. 13 is a diagram illustrating an example of the configuration of a spectroscopic measurement device according to a third embodiment of the present technology. FIG. 2 is a diagram showing the appearance of a prism member. 16A and 16B are a top view and a side view of the spectrometer of FIG. 15 . 1 is a diagram showing an example of a light distribution on a plane on which a light receiving sensor is arranged; 11A and 11B are diagrams illustrating an example of a detection result of a light distribution by a light receiving sensor. FIG. 2 is a block diagram showing an example of the configuration of a calculation unit; 13A and 13B are diagrams illustrating other examples of the appearance of the prism member. FIG. 2 is a diagram showing the appearance of a lens member. FIG. 4 is a diagram for explaining a lens member. 1A and 1B are a top view and a side view showing a configuration example of a spectroscopic measurement device when a lens member is provided. 1A and 1B are a top view and a side view of a spectroscopic measurement device in which a lens member and a cylindrical lens are integrated together. FIG. 1 is a diagram showing an example of the configuration of a spectroscopic measuring device used in thermal gradient spectroscopy. FIG. 1 is a diagram showing an example of the configuration of a spectroscopic measurement device when the surface temperature of a measurement object is changed by laser light. FIG. 13 is a diagram showing another example of the configuration of a spectroscopic measurement device when the surface temperature of an object to be measured is changed by laser light.

Hereinafter, an embodiment of the present technology will be described in the following order.
1. First embodiment 2. Second embodiment 3. Third embodiment 4. Fourth embodiment 5. Modification

1. First embodiment
FIG. 1 is a diagram illustrating an example of a configuration of a spectroscopic measurement device 1 according to a first embodiment of the present technology.

As shown in FIG. 1, the spectroscopic measurement device 1 according to the first embodiment of the present technology is composed of a slit member 11, a lens 12, a biprism 13, a cylindrical lens 14, a light receiving sensor 15, and a calculation unit (not shown).

In the following, the x-axis indicates the lateral direction (horizontal direction) when the spectroscopic measurement device 1 is viewed from the light incident surface side, the y-axis indicates the height direction, and the z-axis indicates the depth direction. The z-axis corresponds to the optical axis of the spectroscopic measurement device 1, and the optical axis indicates the direction of travel of the approximately parallel light beams traveling within the spectroscopic measurement device 1. In addition, the yz plane indicates a plane (first reference plane) that includes the optical axis, and the zx plane indicates a plane (second reference plane) that includes the optical axis and is perpendicular to the yz plane.

The slit member 11 is configured with one rectangular slit, for example, that transmits the measurement light.

Lens 12, like other optical components (biprism 13, cylindrical lens 14) described below, is made of a material that is transparent to the measurement light. When the measurement light is visible light, examples of materials for lens 12 include glass and plastic, and when the measurement light is in the mid-infrared range, examples of materials for lens 12 include silicon and germanium. In addition, like other optical components, lens 12 is desirably treated with an anti-reflection coating to improve light utilization efficiency and prevent stray light. Anti-reflection coating can increase costs, so depending on the design, it may not be necessary to apply an anti-reflection coating.

A variety of processing methods can be applied to optical components made of transparent materials such as the lens 12. For example, the glass molding method is used for glass (optical glass for visible light, and chalcogenide glass for the mid-infrared range), the injection molding method is used for plastic, and cutting is used for germanium and silicon. The processing method for optical components is determined at the discretion of the designer, taking into account mass production and costs.

The biprism 13 is an optical element formed by joining two prisms. The two prisms are joined, for example, along the yz plane.

The cylindrical lens 14 is an optical element having, for example, a semi-cylindrical curved surface on which light enters and extends in the x-axis direction, and a flat exit surface.

The light receiving sensor 15 is a sensor that measures the light distribution. For example, the light receiving sensor 15 is configured as a line sensor in which pixels are arranged in the x-axis direction (in a straight line), and detects the intensity of light incident on each pixel.

The calculation unit calculates the spectrum of the measurement light based on the detection results from the light receiving sensor 15.

FIG. 2 shows a top view and a side view of the spectroscopic measuring device 1 in FIG. 1. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 2, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 2.

For example, measurement light reflected from the object to be measured enters the slit member 11 from the left side of FIG. 2, and the light that passes through the slit is converted into a substantially parallel beam by the lens 12. The lens 12 functions as a beam generator that converts the light that passes through the slit into a substantially parallel beam. The substantially parallel beam is guided to the biprism 13.

As shown in the upper part of Figure 2, the biprism 13 has a shape symmetrical with respect to the yz plane, and the light incidence surface of the biprism 13 is composed of planes SF1 and SF2 inclined at an angle θ around the y axis with respect to the incident light wavefront (plane parallel to the xy plane). In other words, the biprism 13 has two planes whose light incidence or emission surfaces are inclined symmetrically with respect to the yz plane. In yet another way, the biprism 13 is composed of a prism including plane SF1 and a prism including plane SF2 joined along the yz plane.

The angle θ contributes to the pitch of the interference fringes that appear on the light receiving sensor 15, and if the pitch of the interference fringes is d and the wavelength of the measurement light is λ, then the relationship between the angle θ, the pitch d, and the wavelength λ is λ = 2d sin θ. Therefore, the angle θ is set based on the wavelength range for which the spectrum is desired and the pixel pitch of the light receiving sensor 15. Normally, as the wavelength increases, the pixel pitch of the light receiving sensor also increases proportionally, so it is considered preferable to set the angle θ to 1 degree or less regardless of the wavelength, but this is up to the design.

The approximately parallel light beam (measurement light) incident on the biprism 13 is split into two light beams: one refracted by the prism that includes the plane SF1, and the other refracted by the prism that includes the plane SF2. The wavefronts of the two light beams are tilted toward the optical axis, and they are superimposed on the plane where the light receiving sensor 15 is located.

In other words, the biprism 13 splits the approximately parallel light beam into a first light beam (light beam incident on the prism including the plane SF1) and a second light beam (light beam incident on the prism including the plane SF2), refracts and emits the first light beam, and also emits the second light beam in a direction symmetrical to the emission direction of the first light beam with respect to the yz plane, thereby functioning as a light beam splitter that causes interference between the first light beam and the second light beam.

This biprism and light receiving sensor configuration is the classic biprism interferometer configuration, and interference fringes (interferogram) are observed on the light receiving sensor.

FIG. 3 is a diagram showing an example of interference fringes. Note that the example in FIG. 3 shows interference fringes that occur when two light beams split by the biprism 13 are superimposed on the light receiving sensor 15 without passing through the cylindrical lens 14.

On the light receiving sensor 15, the light that has passed through the prism including the plane SF1 and the light that has passed through the prism including the plane SF2 intersect. If the area on the light receiving sensor where the light that has passed through the prism including the plane SF1 is incident is denoted as A1, and the area on the light receiving sensor where the light that has passed through the prism including the plane SF2 is incident is denoted as A2, then interference fringes will occur in area A11 where area A1 and area A2 overlap, as shown in FIG. 3.

Unlike the phase shifter described in Patent Document 2, the biprism 13 of this technology has a structure that is symmetrical with respect to the yz plane, so the interference fringes observed on the light receiving sensor are also perpendicular to the yz plane, making it ideal for measuring spectra.

If a light receiving sensor with pixels arranged in a two-dimensional array is placed behind the biprism, the light receiving sensor can detect interference fringes as shown in Figure 3 (interference light between light transmitted through a prism including plane SF1 and light transmitted through a prism including plane SF2), and the calculation unit can measure the spectrum of the measurement light based on the detection results of the interference fringes. However, since the vertical direction in Figure 3 does not contain any useful information from the perspective of spectrum measurement, there is no problem with compressing (concentrating) the light in the vertical direction.

In terms of size and cost, it is preferable to use a line sensor in which pixels are arranged in a straight line as a light receiving sensor, rather than a sensor in which pixels are arranged in a two-dimensional array. Therefore, in this technology, the light beam transmitted through the biprism 13 is focused on the zx plane by the cylindrical lens 14 (compressing the light in the y-axis direction). The cylindrical lens 14 functions as a focusing section that focuses the light beam transmitted through the biprism 13 on the zx plane. Since the lens 12 and the biprism 13 are both symmetrical with respect to the yz plane, the pitch of the interference fringes does not change even when the light is focused on the zx plane by the cylindrical lens 14.

Figure 4 shows an example of interference fringes compressed by a cylindrical lens 14.

As shown in the upper part of Figure 4, linearly compressed interference fringes are observed on the light receiving sensor 15.

For example, when a phase shifter is used instead of the biprism 13 as in the technology described in Patent Document 2, the two light beams are asymmetric with respect to the yz plane, and therefore oblique interference fringes are formed on the light receiving surface (focal position). If the distance between the cylindrical lens and the light receiving surface deviates from the state in which oblique interference fringes are formed, the interference fringes will have a complex shape. Therefore, in the technology described in Patent Document 2, the distance between the cylindrical lens and the light receiving surface must be set precisely.

In this technology, the interference fringes are formed parallel to the y-axis direction, so even if the distance between the cylindrical lens 14 and the light receiving sensor 15 changes slightly, the image will be blurred in the y-axis direction, but the pitch of the interference fringes will not be affected. Therefore, the spectroscopic measurement device 1 can be said to be a stable and easily adjustable device.

As mentioned above, since the interference fringes are generated in a straight line, it is preferable from a cost perspective to use a line sensor as the light receiving sensor 15. It is desirable for the designer to determine the photoelectric conversion method of the light receiving sensor 15 based on various factors such as the wavelength range for which the spectrum is to be obtained and cost. When the measurement light is in the visible light or near infrared range, a CMOS (Complementary Metal Oxide Semiconductor) line sensor using Si, GaAs, etc. is preferable as the light receiving sensor 15. When the measurement light is in the mid-infrared range, a bolometer, thermopile, MCT (Mercury Cadmium Telluride) sensor, pyroelectric sensor, etc. are preferable as the light receiving sensor 15. It should be noted that the sensors used as the light receiving sensor 15 are not limited to these.

The lower part of Figure 4 shows the detection results of the interference fringes (light distribution) by the light receiving sensor 15. The horizontal axis indicates the pixel position, and the vertical axis indicates the light intensity.

When the measurement light is monochromatic, simple interference fringes such as those shown in Figure 4 are observed, but when the measurement light contains light of multiple wavelengths, interference fringes of various pitches according to the intensity of each wavelength are observed superimposed. Therefore, the calculation unit calculates the spectrum of the measurement light by converting the detection results from the light receiving sensor 15 into the intensity for each wavelength using calculation processing such as Fourier transform.

The order of each component in the spectroscopic measurement device 1 can be changed; for example, the order of the biprism 13 and the cylindrical lens 14 may be reversed. The order of each component is determined at the discretion of the designer. If the incident light is parallel, the slit member 11 and lens 12 are not necessary. For example, when used for astronomical observation or when parallel light is obtained by another optical component, it is possible to configure the spectroscopic measurement device 1 without the slit member 11 and lens 12.

In the above, the functions of generating (converting) parallel light, splitting and refracting parallel light, and focusing are each realized by separate components, but at least two of these functions may be realized by a single component.

FIG. 5 is a top view and a side view showing an example of the configuration of a spectroscopic measuring device 1 in which the functions of generating parallel light and splitting and refracting parallel light are realized by a single component. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 5, and a side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 5.

In FIG. 5, the same components as those in FIG. 2 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 5 differs from the spectroscopic measurement device 1 in FIG. 2 in that a composite member 31 is provided instead of the lens 12 and biprism 13.

Composite member 31 is a member in which lens 12 and biprism 13 are integrated, and is a member that realizes the parallel light generating function realized by lens 12 (Figure 2) and the parallel light splitting and refracting function realized by biprism 13. Composite member 31 is an optical member, for example, in which the light incident surface has a semi-cylindrical curved surface extending in the y-axis direction, and the exit surface has two flat surfaces each inclined by an angle θ around the y-axis with respect to the incident light wavefront.

FIG. 6 is a top view and a side view showing an example of the configuration of a spectroscopic measuring device 1 in which the functions of splitting and refracting parallel light and focusing are achieved by a single component. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 6, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 6.

In FIG. 6, the same components as those in FIG. 2 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 6 differs from the spectroscopic measurement device 1 in FIG. 2 in that a composite member 35 is provided instead of the biprism 13 and cylindrical lens 14.

The composite member 35 is a member in which the biprism 13 and cylindrical lens 14 are integrated, and is a member that realizes the parallel light splitting and refracting function realized by the biprism 13 (Figure 2) and the light focusing function realized by the cylindrical lens 14. The composite member 35 is an optical member, for example, in which the light incident surface has two flat surfaces that are each tilted by an angle θ around the y axis with respect to the incident light wavefront, and the light exit surface has an inverse cylindrical curved surface that extends in the x-axis direction.

Figure 7 shows an example of a slit.

In this technology, basically, only one slit is arranged in the slit member 11, as shown by slit member 11A in FIG. 7. As the slit width (length in the x-axis direction) increases, the contrast of the interference fringes decreases, so a small width is desirable. On the other hand, there are fewer restrictions on the slit length (length in the y-axis direction), and it is sufficient to design it so that light reaches the light receiving sensor 15. The width and length of the slit are determined by the magnification of the optical system and the sensitivity characteristics of the light receiving sensor 15, and are therefore up to the individual design.

As shown by slit member 11B in FIG. 7, multiple slits may be arranged side by side in the slit member 11. This is expected to have the effect of increasing the amount of light that passes through the slit member 11 and thus increasing the intensity of the light that reaches the light receiving sensor 15.

However, at a certain wavelength, the interference fringes caused by light passing through one slit and the interference fringes caused by light passing through the adjacent slit will have the same pitch and will reinforce each other, but at different wavelengths, the interference fringes may weaken each other. Therefore, when the wavelength range for which a spectrum is to be obtained is limited, it is desirable to place multiple slits.

The slit member 11 does not need to be placed at a position upstream of the optical system, and the position of the slit member 11 can be determined by design. For example, as shown in FIG. 8, the slit member 11 may be placed at the focal position of the lens 12 between the lens 12 and the biprism 13. In this case, light reflected from the object to be measured Obj1 is focused by the lens 12, and the focused light passes through the slit and is guided to the biprism 13.

If the slit member 11 is placed at a position after the lens 12, the entire optical system becomes longer, but since the slit member 11 is not exposed on the surface of the spectroscopic measurement device 1, it is possible to prevent the slit member 11 from being damaged. In addition, if the surface of the object to be measured is not flat or if the area for installing the slit member 11 cannot be secured, it is effective to place the slit member 11 in the middle of the optical system.

2. Second embodiment
The biprism 13 is a component that realizes the function of generating two light beams proceeding in two directions, and since this function is not contradictory to the focusing function of the lens 12 (the function of generating parallel light), it is possible to integrate the functions of the lens 12 and the biprism 13.

Figure 9 shows the appearance of the lens member 51.

As shown in FIG. 9, the lens member 51 has a shape that is symmetrical with respect to the yz plane. The lens member 51 is formed, for example, by bonding a portion of a lens (lens piece) having a flat surface on one side and a curved surface on the other side to another lens piece similar to the lens piece. The lens member 51 realizes the functions of the lens 12 and the biprism 13 by integrating them.

FIG. 10 is a diagram for explaining the lens member 51.

When light emitted from a focal point on the optical axis passes through a lens 52, it is converted into a beam of light parallel to the optical axis (the central axis of lens 52). On the other hand, as shown in A of Figure 10, when light emitted from a position P1 that is offset from the optical axis passes through lens 52, it is converted into a beam of light tilted with respect to the optical axis.

The lens member 51 thus realizes a combination of a focusing function and a function of generating two light beams proceeding in two directions, by taking advantage of the fact that light emitted from a position offset from the central axis is converted by the lens into a light beam tilted with respect to the optical axis. Note that in the following, the central axis of the lens piece is assumed to be the same as the central axis of the original lens.

As shown in FIG. 10B, one surface of lens member 51 (e.g., the light entrance surface) is flat, and the other surface (e.g., the light exit surface) has lens surface SF5 and lens surface SF6. In other words, lens member 51 is formed by bonding a lens piece including lens surface SF5 and a lens piece including lens surface SF6 together.

The lens piece including lens surface SF5 is formed so that its central axis C1 is located on the opposite side of the yz plane (the joint surface of the lens piece) on the zx plane. The lens piece including lens surface SF6 is formed so that its central axis C2 is located on the opposite side of the yz plane (the joint surface of the lens piece) on the zx plane. In other words, lens member 51 can be said to be an optical member having two lens surfaces SF5, SF6 whose light entrance surface or exit surface has central axes located on opposite sides of the yz plane.

FIG. 11 is a top view and a side view showing an example of the configuration of the spectroscopic measuring device 1 when a lens member 51 is provided. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 11, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 11.

In FIG. 11, the same components as those in FIG. 2 are denoted by the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 11 differs from the spectroscopic measurement device 1 in FIG. 2 in that a lens member 51 is provided instead of the lens 12 and biprism 13.

The lens piece including lens surface SF5 and the lens piece including lens surface SF6 are formed so that their central axes are located on opposite sides of the yz plane, so that light incident on lens member 51 is refracted by lens surfaces SF5 and SF6 and converted into two beams of light (parallel light) whose wavefronts are tilted toward the optical axis.

In this way, it is possible to integrate the light focusing function and the function of generating two light beams proceeding in two directions with just one of the light entrance and exit surfaces of the lens member 51 (the surface formed by lens surface SF5 and lens surface SF6). Compared to when the lens 12 and biprism 13 are formed separately, the number of parts is reduced, and the reduced number of interfaces is expected to improve efficiency and reduce stray light.

When two lens pieces are joined together, the outer shape of the lens member 51 may not be a perfect circle but may be roughly almond-shaped, as shown in Figure 9. To make it easier to handle, it is possible to process the outer shape of the lens member 51 or provide a flange on the outer periphery.

In addition, instead of integrating the functions of the lens 12 and the biprism 13, it is also possible to integrate the functions of the biprism 13 and the cylindrical lens 14.

Figure 12 shows the appearance of the lens member 55.

Lens member 55 in FIG. 12 has a shape symmetrical with respect to the yz plane. For example, lens member 55 is configured such that one surface SF7 has a flat surface, and the other surface SF8 is inclined at an angle θ about the y axis with respect to the incident light wave surface (a surface parallel to the xy plane) when viewed from above, and is formed to have a semi-cylindrical curved surface when viewed from the side.

The lens member 55 combines the function of generating two light beams going in two directions using the biprism 13 with the function of focusing the light in a straight line using the cylindrical lens 14, and can achieve this with just the light exit surface (surface SF8).

FIG. 13 shows a top view and a side view of the spectroscopic measuring device 1 when the lens member 51 and the cylindrical lens 14 are integrated. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 13, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 13.

In FIG. 13, the same components as those in FIG. 2 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 13 differs from the spectroscopic measurement device 1 in FIG. 2 in that a composite member 61 is provided instead of the lens 12, the biprism 13, and the cylindrical lens 14.

The composite member 61 is a member in which the lens member 51 and the cylindrical lens 14 are integrated. The light incident surface of the composite member 61 has a lens surface SF11 corresponding to the lens surface SF5 of the lens member 51, and a lens surface SF12 of the lens member 51. The light exit surface of the composite member 61 has a semi-cylindrical curved surface SF13 extending in the x-axis direction.

In this case, the light incident on the composite member 61 is converted into two light beams traveling in two directions by lens surface SF11 and lens surface SF12, and the two light beams are focused in the y-axis direction by curved surface SF13.

FIG. 14 shows a top view and a side view of the spectroscopic measuring device 1 when the lens 12 and the lens member 55 are integrated. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 14, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 14.

In FIG. 14, the same components as those in FIG. 2 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 14 differs from the spectroscopic measurement device 1 in FIG. 2 in that a composite member 62 is provided instead of the lens 12, the biprism 13, and the cylindrical lens 14.

Composite member 62 is a member in which lens 12 and lens member 55 are integrated. The light entrance surface of composite member 62 has lens surface SF21 corresponding to the lens surface of lens 12, and the light exit surface of composite member 62 has surface SF22 corresponding to surface SF8 of lens member 55.

In this case, the light incident on the composite member 61 is converted into a substantially parallel beam by the lens surface SF21, and the substantially parallel beam is converted into two beams traveling in two directions by the surface SF22, and the two beams are focused on the zx plane.

As described above, it is possible to assign functions to each of the light entrance and exit surfaces of an optical component. When forming an optical component such as composite member 61 or composite member 62, the difficulty of processing the material increases, but because all optical functions can be concentrated in one component, it is possible to expect benefits such as improved light utilization efficiency, miniaturization, and reduction of stray light.

3. Third embodiment
Fig. 15 is a diagram showing a configuration example of a spectroscopic measurement device 1 according to a third embodiment of the present technology. In Fig. 15, the same components as those in Fig. 1 are denoted by the same reference numerals. Duplicate descriptions will be omitted as appropriate.

The spectroscopic measurement device 1 in FIG. 15 differs from the spectroscopic measurement device 1 in FIG. 1 in that a prism member 101 is provided instead of the biprism 13, and that light receiving sensors 111 and 112 are provided instead of the light receiving sensor 15.

The prism member 101 is formed by joining three prisms. Two of the three prisms are joined, for example, along the yz plane, and one prism is joined, for example, along the zx plane to the two prisms joined along the yz plane.

The light receiving sensors 111 and 112 are each composed of a line sensor with pixels arranged in the x-axis direction, for example. The light receiving sensor 111 (second line sensor) detects a light beam that does not generate interference fringes, and the light receiving sensor 112 (first line sensor) detects interference fringes (interfering light). The light receiving sensors 111 and 112 are arranged in the y-axis direction; in other words, the light receiving sensor is composed of multiple pixels arranged in an array of two rows and multiple columns.

The calculation unit calculates the spectrum of the measurement light based on the detection results from the light receiving sensors 111 and 112. The method of calculating the spectrum by the calculation unit will be described later.

FIG. 16 shows the external appearance of the prism member 101.

While the light incidence surface of the biprism 13 is composed of two planes SF1 and SF2 tilted symmetrically around the y-axis with respect to the incident light wavefront, the light incidence surface of the prism member 101 is composed of planes SF51 and SF52 corresponding to planes SF1 and SF2 of the biprism 13, and plane SF53 tilted with respect to the incident light wavefront. Plane SF53 is a plane tilted with respect to the x-axis with respect to the incident light wavefront. In other words, the prism member 101 can be said to be an optical member in which the light incidence surface or emission surface has two planes tilted symmetrically with respect to the yz plane and one plane tilted with respect to the zx plane.

In order to ensure the symmetry of the interference fringes observed on the light receiving sensors 111 and 112, it is desirable for the prism member 101 to have a shape that is symmetrical with respect to the yz plane. In other words, it is desirable for the prism member 101 to be formed so that the planes SF51 and SF52 are disposed symmetrically with respect to the yz plane, and the plane SF53 is symmetrical with respect to the yz plane.

FIG. 17 shows a top view and a side view of the spectroscopic measuring device 1 in FIG. 15. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 17, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 17.

For example, measurement light reflected from the object to be measured enters the slit member 11 from the left side of FIG. 17, and the light that passes through the slit is converted into a substantially parallel beam by the lens 12. The substantially parallel beam is guided to the prism member 101.

The approximately parallel light beam incident on the prism member 101 is split into three light beams: a light beam refracted by a prism including a plane SF51 (first light beam), a light beam refracted by a prism including a plane SF52 (second light beam), and a light beam refracted by a prism including a plane SF53 (third light beam).

As described in the first embodiment, the wavefronts of the light beam refracted by the prism including the plane SF51 and the light beam refracted by the prism including the plane SF52 are tilted toward the optical axis (x-axis direction), and the light beams are focused by the cylindrical lens 14 onto the light receiving sensor 112 and overlapped on the light receiving sensor 112. Therefore, interference fringes are observed on the light receiving sensor 112.

The light beam refracted by the prism including the plane SF51 and the light beam refracted by the prism including the plane SF52 are used to measure the spectrum.

On the other hand, the wavefront of the light beam refracted by the prism including the plane SF53 is tilted toward the optical axis (y-axis direction), and the light is focused by the cylindrical lens 14 onto the light receiving sensor 111, which is located at a different position from the light receiving sensor 112.

FIG. 18 is a diagram showing an example of light distribution on a plane on which the light receiving sensors 111 and 112 are arranged.

As shown in FIG. 18, interference fringes occur in the lower portion of the plane where light receiving sensors 111 and 112 are arranged (where light receiving sensor 112 is arranged). On the other hand, no interference fringes occur in the upper portion of the plane (where light receiving sensor 111 is arranged), because only the light beam refracted by the prism including plane SF53 is focused.

By placing the light receiving sensor 112 in the lower section where interference fringes occur, and the light receiving sensor 111 in the upper section where interference fringes do not occur, it is possible to detect both the light distribution without interference fringes and the light distribution with interference fringes.

Note that Figure 18 shows the light distribution when the slit is infinitesimal, and no light reaches the middle part of the plane where light receiving sensors 111 and 112 are arranged. In reality, the length of the slit in the y-axis direction is finite, and the longer the length of the slit in the y-axis direction, the wider the upper and lower parts where light reaches, and the dark band in the middle part is eroded. The length of this dark band in the y-axis direction is determined by the inclination angle of plane SF53 of prism member 101, so the inclination angle of plane SF53 is appropriately designed based on the length of the slit in the y-axis direction and the distance between light receiving sensors 111 and 112.

In the example of FIG. 18, the light beam refracted by the prism including the plane SF53, and the interference light formed by superimposing the light beam refracted by the prism including the plane SF51 and the light beam refracted by the prism including the plane SF52 are not focused on a single line. This phenomenon occurs due to aberrations of the lens 12 and the cylindrical lens 14, etc.

In reality, noise (stray light) occurs when light is unevenly distributed overall or locally due to reflection, scattering, diffraction, etc. at each component. In addition, light receiving sensors generate noise caused by devices such as dark current and fixed pattern noise. Because signals resulting from various factors that differ from ideal conditions are input to the light receiving sensor, the detection results from the light receiving sensor contain a significant amount of bias component.

Since the detection results by the light receiving sensors 111 and 112 are considered to contain similar bias components, the calculation unit of the spectroscopic measurement device 1 can use the detection results by the light receiving sensors 111 to remove the bias components contained in the detection results by the light receiving sensors 112.

FIG. 19 is a diagram showing an example of the detection results of light distribution by light receiving sensor 111 and light receiving sensor 112. In FIG. 19, the horizontal axis indicates the pixel position, and the vertical axis indicates the light intensity.

In the upper part of Figure 19, the detection result by light receiving sensor 111 is shown by a dotted line, and the detection result by light receiving sensor 112 is shown by a solid line. Because the combined area of planes SF51 and SF52 is different from the area of plane SF53, the intensities of light detected by light receiving sensors 111 and 112 are different. However, in the example at the top of Figure 19, the detection results by light receiving sensors 111 and 112 have been adjusted so that their integral values match.

For example, if we assume that the maximum sensitivity of the light receiving sensor is 1, a bias component of about 0.2 is included in the entire detection result, so the maximum value of the detection result by the light receiving sensor 111 is approximately 0.33. Therefore, a gain of only about 3 times at most can be applied to the detection result by the light receiving sensor 111.

The lower part of Figure 19 shows the difference between the detection results by light receiving sensors 111 and 112. Since the maximum difference between the detection results by light receiving sensors 111 and 112 is approximately 0.1, a gain of approximately 10 times can be applied to this difference. Therefore, by differentially amplifying the detection results by light receiving sensors 111 and 112, a large gain can be applied to the detection results of the optical distribution of interference fringes, making it possible to measure the spectrum with high accuracy.

As mentioned above, there are various types of light receiving sensors, but since sufficient output cannot be obtained by photoelectric conversion alone, many types of light receiving sensors are provided with an amplifier circuit in the subsequent stage. The amplifier circuit is provided, for example, as part of the calculation unit.

If the amount of light flux incident on plane SF51 and plane SF52 is expected to be equal to the amount of light flux incident on plane SF53, the bias component can be removed without being affected by noise generated during amplification by the amplifier circuit by subtracting the output of light receiving sensor 111 from the output of light receiving sensor 112 before amplifying them. For example, if a sensor with polarity such as a pyroelectric sensor is used as the light receiving sensor, the bias component can be effectively removed by reversing the polarity of light receiving sensor 111 and light receiving sensor 112 and connecting each pixel by column.

The ratio of the amount of light flux incident on plane SF51 and plane SF52 to the amount of light flux incident on plane SF53 is desirably determined by design conditions and noise conditions. For example, if the bias component due to stray light is relatively small, it is desirable to reduce the relative area of plane SF53 and increase the amount of light flux focused on the light receiving sensor 112. In an optical system with no bias component at all, it is desirable to use a biprism 13 instead of the prism member 101.

For example, when a sensor that does not have polarity and whose output changes according to the amount of light received, such as a Si sensor or a bolometer, is used as the light receiving sensor, an amplifier circuit is provided for each light receiving sensor (light receiving sensor 111 and light receiving sensor 112).

FIG. 20 is a block diagram showing an example of the configuration of the calculation unit.

As shown in FIG. 20, the calculation unit is composed of, for example, amplifier circuits 151 and 152, a gain calculation unit 153, a differential amplifier circuit 154, and a spectrum calculation unit 155.

The amplifier circuit 151 applies a gain (first gain) to the output (detection result) of the light receiving sensor 111 and supplies the result to the differential amplifier circuit 154.

The amplifier circuit 152 applies a gain (second gain) to the output (detection result) of the light receiving sensor 112 and supplies it to the differential amplifier circuit 154.

Gain calculation unit 153 calculates the gain value to be applied to the output of the light receiving sensor in amplifier circuit 151 and amplifier circuit 152, respectively, and controls amplifier circuit 151 and amplifier circuit 152.

The differential amplifier circuit 154 amplifies the difference between the output of the light receiving sensor 111 to which a gain has been applied by the amplifier circuit 151 and the output of the light receiving sensor 112 to which a gain has been applied by the amplifier circuit 152, and supplies the amplified difference to the spectrum calculation unit 155.

The spectrum calculation unit 155 performs calculations such as Fourier transform based on the difference supplied from the differential amplifier circuit 154 to calculate the spectrum of the measurement light.

In this way, the calculation unit can balance the outputs of the light receiving sensors 111 and 112 by the gain calculation unit 153 appropriately adjusting the amount of amplification by the amplifier circuits 151 and 152.

For example, the gain in the amplifier circuits 151 and 152 is adjusted so that the integral or average value of the pixel values of all pixels of the light receiving sensor 111 is the same as the integral or average value of the pixel values of all pixels of the light receiving sensor 112.

Also, for example, since the difference between the outputs of the light receiving sensors 111 and 112 includes positive and negative values, the gains in the amplifier circuits 151 and 152 are adjusted so that the integral value of the difference between the outputs of the light receiving sensors 111 and 112 is minimized. Here, both bias components that occur regardless of the amount of incident light flux, such as fixed noise and dark current, and bias components that occur depending on the amount of incident light flux, such as stray light, may be included in the output from the light receiving sensor. There may also be variations in sensitivity for each pixel of the light receiving sensor. In these cases, it is desirable to adjust the gains in the amplifier circuits 151 and 152 taking into account only the bias components that depend on the amount of incident light flux after removing the bias components that occur regardless of the amount of incident light flux. In this case, the integral value of the difference between the outputs of the light receiving sensors 111 and 112 is not necessarily minimized.

The gain values in the amplifier circuits 151 and 152 may be recorded in a recording unit provided in the spectrometer 1 during the adjustment process when producing the spectrometer 1, or may be dynamically adjusted when measuring the spectrum.

If the differential amplifier circuit 154 outputs positive and negative voltages, it is necessary to supply a negative voltage to the differential amplifier circuit 154, which may complicate the circuitry of the calculation unit. In this case, adding a predetermined bias voltage so that the voltage output from the differential amplifier circuit 154 becomes a positive voltage can prevent the circuitry of the calculation unit from becoming complicated.

The specific shape of the prism member is determined as appropriate by the designer. As long as it is possible to generate at least two light beams that form interference fringes and at least one light beam that does not form interference fringes from one substantially parallel light beam, the shape of the prism member is not limited to the shape described with reference to FIG. 16.

Figure 21 shows another example of the appearance of a prism member.

As shown in A of FIG. 21, the light incidence surface of the prism member 102 has planes SF51 and SF52 corresponding to planes SF1 and SF2 of the biprism 13, a plane SF53 tilted with respect to the wavefront of the incident light, and a plane SF54 tilted at an angle different from plane SF53 with respect to the wavefront of the incident light. Planes SF53 and SF54 are planes tilted about the x-axis with respect to the wavefront of the incident light.

On the plane on which the light receiving sensors 111 and 112 are arranged, the light is not actually focused in a straight line due to the influence of, for example, the aberration of the cylindrical lens 14, and the light spreads up and down from the bright linear portion. When the light incident surface is viewed from the front, by arranging the planes SF51 and SF52 in the middle and the planes SF53 and SF54 in the upper and lower stages, as in the prism member 102, only the light beam refracted by the planes SF53 and SF54 is strongly affected by the aberration of the cylindrical lens 14, and the light beam refracted by the planes SF51 and SF52 is not greatly affected by the aberration.

Therefore, the light beam that is strongly affected by the aberration of the cylindrical lens 14 can be used to remove the bias, and the light beam that is not so affected by the aberration can be used to detect the interference fringes.

In addition, in the prism member 102, since the inclination angles of the planes SF53 and SF54 are different, the light beam used for bias removal is focused at two locations. For example, as shown in the prism member 103 of FIG. 21B, the inclination angles of the planes SF53 and SF54 may be adjusted so that the light beam refracted by the planes SF53 and SF54 is focused at one location.

As shown in prism member 104 in FIG. 21C, when the light incidence surface is viewed from the front, planes SF51 and SF52 may be arranged in the center, and plane SF55, which is tilted around the x-axis with respect to the wavefront of the incident light, may be arranged to surround planes SF51 and SF52. In this case, the light beam that is strongly affected by the aberration of lens 12 can be used for bias removal.

4. Fourth embodiment
As in the second embodiment, the function of the lens 12 and the function of the prism member 101 can be integrated.

Figure 22 shows the external appearance of the lens member 201.

As shown in FIG. 22, the lens member 201 has a shape that is symmetrical with respect to the yz plane. The lens member 201 is formed by, for example, bonding three lens portions (lens pieces) each having a flat light exit surface and a curved light entrance surface.

The light incidence surface of lens member 201 has lens surfaces SF101, SF102, and SF103. In lens member 201, the lens piece including lens surface SF101 and the lens piece including lens surface SF102 are bonded along the yz plane. Lens surface SF101 corresponds to lens surface SF5 (FIG. 10) of lens member 51, and lens surface SF102 corresponds to lens surface SF6 of lens member 51. In lens member 201, lens surface SF103 is bonded to each of the lens pieces including lens surface SF101 and lens surface SF102, and corresponds to plane SF53 of prism member 101.

The lens member 201 realizes the functions of the lens 12 and the prism member 101 by integrating them.

FIG. 23 is a diagram for explaining the lens member 201.

The lens piece including the lens surface SF101 is formed so that its central axis C101 (center point P51) is located on the opposite side of the yz plane (the joint surface of the lens piece) on a plane parallel to the zx plane. The lens piece including the lens surface SF102 is formed so that its central axis C102 (center point P52) is located on the opposite side of the yz plane (the joint surface of the lens piece) on a plane parallel to the zx plane.

Furthermore, the lens piece including lens surface SF103 is formed so that its central axis (center point P53) is located on the opposite side of the zx plane on the yz plane. In other words, it can be said that lens member 201 is an optical member having a light entrance surface or exit surface with two lens surfaces whose central axes are located on opposite sides of the yz plane, and one lens surface whose central axis is located on the opposite side of the zx plane. As long as the central axis of the lens piece including lens surface SF103 does not coincide with the optical axis, it does not matter where it is located on the yz plane. The position of the central axis of the lens piece including lens surface SF103 can be designed based on the position where it is desired to focus the light beam used for bias removal.

FIG. 24 is a top view and a side view showing an example of the configuration of the spectroscopic measuring device 1 when a lens member 201 is provided. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 24, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 24.

In FIG. 24, the same components as those in FIG. 17 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 24 differs from the spectroscopic measurement device 1 in FIG. 17 in that a lens member 201 is provided instead of the lens 12 and prism member 101.

The lens piece including lens surface SF101 and the lens piece including lens surface SF102 are formed so that their central axes are located on opposite sides of the yz plane, so that light incident on lens member 201 is refracted by lens surfaces SF101 and SF102 and converted into two light beams whose wavefronts are tilted toward the optical axis (y-axis direction).

The light beam refracted by the lens piece including the lens surface SF101 and the light beam refracted by the lens piece including the lens surface SF102 are focused on the light receiving sensor 112 by the cylindrical lens 14 and overlapped on the light receiving sensor 112.

In addition, since the lens piece including the lens surface SF103 is formed so that its central axis is located on the opposite side of the zx plane, the light incident on the lens member 201 is refracted by the lens surface SF103 and converted into a light beam whose wavefront is tilted toward the optical axis (x-axis direction).

The light beam refracted by the lens piece including the lens surface SF103 is focused onto the light receiving sensor 111 by the cylindrical lens 14.

In this way, it is possible to integrate the light collecting function and the function of generating three light beams proceeding in three directions with just one of the light entrance and exit surfaces of the lens member 201 (the surface formed by lens surfaces SF101, SF102, and SF103). Compared to when the lens 12 and the prism member 101 are formed separately, the number of parts is reduced, and the reduced number of interfaces is expected to improve efficiency and reduce stray light.

FIG. 25 shows a top view and a side view of the spectroscopic measuring device 1 when the lens member 201 and the cylindrical lens 14 are integrated. The top view of the spectroscopic measuring device 1 is shown in the upper part of FIG. 25, and the side view of the spectroscopic measuring device 1 is shown in the lower part of FIG. 25.

In FIG. 25, the same components as those in FIG. 17 are given the same reference numerals. Duplicate explanations will be omitted as appropriate. The spectroscopic measurement device 1 in FIG. 25 differs from the spectroscopic measurement device 1 in FIG. 17 in that a composite member 211 is provided instead of the lens 12, the prism member 101, and the cylindrical lens 14.

Composite member 211 is a member in which lens member 201 and cylindrical lens 14 are integrated. The light incident surface of composite member 211 has lens surface SF111 corresponding to lens surface SF101 of lens member 201, lens surface SF112 corresponding to lens surface SF102 of lens member 201, and lens surface SF113 corresponding to lens surface SF103 of lens member 201. The light exit surface of composite member 211 has a semi-cylindrical curved surface SF121 extending in the x-axis direction.

In this case, the light incident on the composite member 211 is converted into three light beams traveling in three directions by the lens surfaces SF111, SF112, and SF113, and the three light beams are focused in the y-axis direction by the curved surface SF121.

As described above, it is possible to assign functions to each of the light entrance and exit surfaces of the optical component. When forming the composite component 211, it is more difficult to process the material, but since all optical functions can be concentrated in one component, it is expected to have effects such as improved light utilization efficiency, miniaturization, and reduction of stray light.

5. Modifications
In the spectroscopic measurement device 1 of the present technology, there is no limitation on the wavelength of the measurement light. Currently, many small devices are commercially available as spectroscopes from the visible light region to the near infrared region, so it is expected that the spectroscopic measurement device 1 of the present technology will be applied to a spectroscope in the mid-infrared region.

Currently, spectrometers using a Michelson interferometer are widely used as mid-infrared spectroscopes. However, because a Michelson interferometer has moving parts, the spectroscope is not very robust and is not very portable. In addition, a Michelson interferometer requires a certain amount of time for the mirror to scan in order to obtain a single spectrum, so the spectroscope is not suitable for applications such as measuring moving samples or observing the time response to some kind of stimulus.

The spectroscopic measurement device 1 of this technology can be used for transmission measurement, reflection measurement, ATR (Attenuated Total Reflection), etc., in the same way as a spectrometer using a Michelson interferometer.

Because the optical components are arranged on a substantially uniform axis, the spectroscopic measuring device 1 of this technology is smaller than a spectrometer that uses a Michelson interferometer, and because it has no moving parts, the spectroscopic measuring device 1 of this technology is highly robust. Furthermore, because a line sensor is used as the light receiving sensor 15, it is possible to measure the spectrum at high speed.

Because it can measure spectra at high speed, the spectroscopic measurement device 1 of this technology can suitably measure the spectral response of a measured object to a certain stimulus that would be difficult to measure with a spectrometer that uses a Michelson interferometer.

The spectroscopic measuring device 1 of the present technology can be used, for example, in thermal gradient spectroscopy. In thermal gradient spectroscopy, the surface of the object to be measured is heated with a heater, and the increase in radiant light emitted from the surface of the heated object to be measured is observed while being split into spectra, thereby allowing the absorption spectrum of the object to be calculated.

FIG. 26 shows an example of the configuration of a spectroscopic measuring device 1 used in thermal gradient spectroscopy.

The spectroscopic measurement device 1 in FIG. 26 is configured with a slit member 301, a lens 12, a prism member 101, a cylindrical lens 14, and a light receiving sensor 112 (light receiving sensor 111) arranged approximately on a single axis.

At least one slit is arranged in the slit member 301. The slit member 301 is arranged in close contact with the object to be measured Obj11, and also functions as a temperature change section that changes the surface of the object to be measured Obj11.

The slit member 301 is formed by patterning a heater circuit on a transparent material such as germanium. In the slit member 301, the opening of the heater circuit is formed so as to function as a slit. Because the heater is provided in the slit member 301, the surface of the object to be measured Obj11 around the slit can be suitably heated without having to provide a heater and a slit member separately.

The spectroscopic measurement device 1 of this technology can measure spectra at high speeds, so it can continuously measure spectra in sync with the heating of the heater (changes in the surface temperature of the object being measured) and measure the response of each wavelength of radiant light to changes in surface temperature, ultimately measuring the absorption spectrum of the object being measured.

In addition, instead of a heater, for example, laser light may be used to change the surface temperature of the object being measured.

FIG. 27 shows an example of the configuration of the spectroscopic measurement device 1 when the surface temperature of the object to be measured is changed by laser light.

For example, if the wavelength of the radiated light from the object to be measured is assumed to be 6 to 13 μm, the surface of the object to be measured is heated with laser light having a wavelength of, for example, 3 μm. In this case, the spectroscopic measurement device 1 in FIG. 27 is configured with the lens 12, long-pass filter 311, slit member 11, prism member 101, cylindrical lens 14, and light receiving sensor (not shown) arranged approximately on one axis.

As shown by the arrow in Figure 27, the laser light is introduced from the side of the optical axis of the spectroscopic measurement device 1, reflected by the long-pass filter 311, and irradiated onto the surface of the object to be measured Obj21. The radiated light emitted from the object to be measured Obj21 passes through the lens 12, the long-pass filter 311, the slit member 11, the prism member 101, and the cylindrical lens 14, and is focused on the light receiving sensor.

The laser light is reflected by the object to be measured Obj21 side of the long-pass filter 311 and does not pass through to the light receiving sensor, so only the radiated light from the object to be measured Obj21 can be detected by the light receiving sensor.

FIG. 28 shows another example of the configuration of the spectroscopic measurement device 1 when the surface temperature of the object to be measured is changed by laser light.

The spectroscopic measurement device 1 in FIG. 28 is composed of a lens 12, a parabolic mirror 321, a slit member 11, a prism member 101, a cylindrical lens 14, a light receiving sensor (not shown), and a light source of laser light.

The parabolic mirror 321 has a through hole formed in its mirror surface. Laser light emitted from a laser light source passes through the through hole of the parabolic mirror 321 as shown by the arrow in FIG. 28, and is irradiated onto the surface of the object to be measured Obj31 from the top to the bottom in FIG. 28. The laser light source functions as a temperature change unit that changes the surface temperature of the object to be measured by irradiating the surface of the object to be measured with laser light.

The mirror surface of the parabolic mirror 321 is tilted to the right in FIG. 28 with respect to the object to be measured Obj31. The radiant light emitted from the object to be measured Obj31 in the upward direction in FIG. 28 is converted into a parallel beam by the lens 12, and the parallel beam is focused to the right in FIG. 28 by the mirror surface of the parabolic mirror 321 and passes through the slit member 11, the prism member 101, and the cylindrical lens 14.

The spectroscopic measuring device 1 of the present technology can measure the absorption spectrum of a subject in the mid-infrared range regardless of the thickness of the subject, and can therefore be used to measure the absorption spectrum of a living body, for example. In this case, the reflected light, transmitted light, scattered light, etc. incident on the living body are converted into parallel beams of light by the lens 12, and are then split into at least two beams of light by the prism member 101 or the like, and are used to measure the absorption spectrum of the living body. For example, the spectroscopic measuring device 1 of the present technology can be used to measure the moisture content of the skin, and subcutaneous blood glucose and cholesterol levels.

Note that the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

The embodiment of this technology is not limited to the above-mentioned embodiment, and various modifications are possible without departing from the spirit of this technology.

<Examples of configuration combinations>
The present technology can also be configured as follows.

(1)
a beam splitter that splits a substantially parallel beam into a first beam and a second beam, refracts and emits the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to a first reference plane including a traveling direction of the substantially parallel beam, thereby causing interference between the first beam and the second beam;
a focusing unit that focuses the first light beam and the second light beam on a second reference plane that includes a traveling direction of the substantially parallel light beam and is perpendicular to the first reference plane;
a sensor unit that detects interference light between the first light beam and the second light beam;
and a calculation unit that calculates a spectrum of the approximately parallel light beam based on a detection result by the sensor unit.
(2)
The measurement device according to (1), wherein the light beam splitter is constituted by an optical member having a light entrance surface or an exit surface thereof, the light entrance surface or the exit surface being constituted by two flat surfaces that are inclined symmetrically with respect to the first reference plane.
(3)
The measurement device described in (1) above, wherein the light beam splitting unit is composed of an optical member having two lens surfaces whose light entrance surface or exit surface has a central axis located on opposite sides of the first reference plane.
(4)
The measuring device according to any one of (1) to (3), wherein the sensor unit is constituted by a line sensor in which pixels are arranged in a straight line.
(5)
The measurement apparatus according to (4), wherein the beam splitter further splits the substantially parallel beam into a third beam.
(6)
The measurement device described in (5) above, wherein the light beam splitting unit is composed of an optical element having a light entrance surface or exit surface that has two planes inclined symmetrically with respect to the first reference plane and one plane inclined with respect to the second reference plane.
(7)
The measurement device described in (5), wherein the light beam splitting unit is composed of an optical element having an entrance surface or exit surface of light, two lens surfaces each having a central axis located on the opposite side of the first reference plane, and one lens surface having a central axis located on the opposite side of the second reference plane.
(8)
The measuring device according to any one of (5) to (7), wherein the sensor unit is composed of a first line sensor that detects the interference light and a second line sensor that detects the third light beam.
(9)
The measurement device according to (8), wherein the calculation unit calculates the spectrum based on a detection result by the first line sensor and a detection result by the second line sensor.
(10)
The measurement device according to (9), wherein the calculation unit amplifies a difference between a detection result by the first line sensor and a detection result by the second line sensor, and calculates the spectrum based on the amplified difference.
(11)
The measurement device described in (10), wherein the calculation unit multiplies the detection result by the first line sensor by a first gain, multiplies the detection result by the second line sensor by a second gain, and then amplifies the difference between the detection result by the first line sensor and the detection result by the second line sensor.
(12)
The measurement device according to (11), wherein the calculation unit adjusts the first gain and the second gain.
(13)
The measuring device according to (8), wherein each pixel of the first line sensor and each pixel of the second line sensor are connected for each column.
(14)
A slit member having a slit arranged therein;
The measurement device according to any one of (1) to (13), further comprising: a light beam generating unit that converts the light transmitted through the slit into the approximately parallel light beam.
(15)
Further comprising a temperature change unit for changing a surface temperature of the object to be measured,
The measuring device according to (14) above, wherein the light transmitted through the slit is radiant light emitted from a surface of the object to be measured.
(16)
The measurement device according to (15), wherein the calculation unit calculates the spectrum in synchronization with a change in surface temperature of the object to be measured caused by the temperature change unit.
(17)
The measuring device according to (15) or (16), wherein the temperature change unit is constituted by a heater provided in the slit member.
(18)
The measuring device according to (15) or (16), wherein the temperature change unit changes a surface temperature of the object to be measured by irradiating a surface of the object to be measured with light.
(19)
The measurement device according to any one of (14) to (18), wherein the light beam generating section and the light beam splitting section, or the light beam splitting section and the light collecting section, are configured by a single optical member.
(20)
The measurement device according to any one of (1) to (19), wherein the beam splitter splits light incident from a living body into the first beam and the second beam.

1 Spectroscopic measurement device, 11 Slit member, 12 Lens, 13 Biprism, 14 Cylindrical lens 14 Light receiving sensor, 31, 35 Composite member, 51, 55 Lens member, 61, 62 Composite member, 101 to 104 Prism member, 111, 112 Light receiving sensor, 151, 152 Amplification circuit, 153 Gain calculation unit, 154 Differential amplification circuit, 155 Spectral calculation unit, 201 Lens member, 211 Composite member, 301 Slit member, 311 Long pass filter, 321 Parabolic mirror

Claims (20)

a beam splitter that splits a substantially parallel beam into a first beam and a second beam, refracts and emits the first beam, and emits the second beam in a direction symmetrical to the emission direction of the first beam with respect to a first reference plane including a traveling direction of the substantially parallel beam, thereby causing interference between the first beam and the second beam;
a focusing unit that focuses the first light beam and the second light beam on a second reference plane that includes a traveling direction of the substantially parallel light beam and is perpendicular to the first reference plane;
a sensor unit that detects interference light between the first light beam and the second light beam;
and a calculation unit that calculates a spectrum of the approximately parallel light beam based on a detection result by the sensor unit. The measurement device according to claim 1 , wherein the light beam splitter is configured by an optical member having a light entrance surface or an exit surface thereof, the light entrance surface or the exit surface having two flat surfaces inclined symmetrically with respect to the first reference plane. The measurement device according to claim 1 , wherein the light beam splitter is configured by an optical member having two lens surfaces, each of which has a light entrance surface or an exit surface, and whose central axes are located on opposite sides of the first reference plane. The measuring device according to claim 1 , wherein the sensor unit is configured by a line sensor in which pixels are arranged in a straight line. The measurement device according to claim 4 , wherein the beam splitter further splits the substantially parallel beam into a third beam. The measurement device according to claim 5 , wherein the light beam splitter is configured with an optical member having a light entrance surface or exit surface that has two planes inclined symmetrically with respect to the first reference plane and one plane inclined with respect to the second reference plane. The measurement device according to claim 5 , wherein the light beam splitting unit is configured with an optical member having an entrance surface or an exit surface of light, two lens surfaces each having a central axis located on opposite sides of the first reference plane, and one lens surface having a central axis located on the opposite side of the second reference plane. The measuring device according to claim 5 , wherein the sensor unit is configured with a first line sensor that detects the interference light and a second line sensor that detects the third light beam. The measurement device according to claim 8 , wherein the calculation section calculates the spectrum based on a detection result by the first line sensor and a detection result by the second line sensor. The measurement device according to claim 9 , wherein the calculation section amplifies a difference between a detection result by the first line sensor and a detection result by the second line sensor, and calculates the spectrum based on the amplified difference. The measuring device of claim 10, wherein the calculation unit multiplies the detection result by the first line sensor by a first gain and the detection result by the second line sensor by a second gain, and then amplifies the difference between the detection result by the first line sensor and the detection result by the second line sensor. The measurement device according to claim 11 , wherein the calculation section adjusts the first gain and the second gain. The measuring device according to claim 8 , wherein each pixel of the first line sensor and each pixel of the second line sensor are connected for each column. A slit member having a slit arranged therein;
The measurement device according to claim 1 , further comprising: a light beam generating unit that converts the light transmitted through the slit into the approximately parallel light beam. Further comprising a temperature change unit for changing a surface temperature of the object to be measured,
The measuring device according to claim 14 , wherein the light transmitted through the slit is radiant light emitted from a surface of the object to be measured. The measurement device according to claim 15 , wherein the calculation section calculates the spectrum in synchronization with a change in the surface temperature of the object to be measured caused by the temperature change section. The measuring device according to claim 15 , wherein the temperature change unit is configured by a heater provided in the slit member. The measurement device according to claim 15 , wherein the temperature change unit changes the surface temperature of the object to be measured by irradiating a surface of the object to be measured with light. The measurement device according to claim 14 , wherein the light beam generating section and the light beam splitting section, or the light beam splitting section and the light collecting section, are configured by a single optical member. The measurement device according to claim 1 , wherein the beam splitter splits the light incident from the living body into the first beam and the second beam.

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