WO2023185199A1 - Spectral confocal measurement device - Google Patents

Abstract

A spectral confocal measurement device (200), comprising a light source assembly (210) for emitting incident light, an optical sampling portion (220) connected to the light source assembly (210), and a measurement portion (230). The optical sampling portion (220) comprises a light-incident hole, a light-emergent hole (221) and a dispersive lens group (222); and the light source assembly (210) and the optical sampling portion (220) are configured to make the incident light enter a first side of the dispersive lens group (222) from the light-incident hole in the form of a linear light source and make the incident light focus on different measurement surfaces of an object to be measured, a second side of the dispersion lens group (222) outputs reflected light, and the reflected light enters the measurement portion (230) through the light-emergent hole (221), such that a measurement result is obtained, and the first side and the second side do not overlap.

Description

Spectral confocal measurement device Technical field

The present application relates to the technical field of optical shift measurement, and in particular to a spectral confocal measurement device.

Background technique

In recent years, with the rapid development of precision manufacturing, the requirements for measurement technology have also greatly increased. The spectral confocal sensor is a non-contact displacement sensor based on wavelength shift modulation. Because its measurement accuracy reaches the submicron or even nanometer level, it is not sensitive to object tilt, surface texture, etc., and it also has strong resistance to stray light. , which has quickly become a hot spot in current research and is widely used in fields such as film thickness measurement, precision positioning, and precision instrument manufacturing.

The spectral confocal measurement system based on spectral confocal technology uses a light source to illuminate the surface of the object to be measured, and a CCD industrial camera or spectrometer detects the reflected spectral information to determine the peak wavelength focused on the object surface, thereby obtaining the surface of the object to be measured. Axial distance information. The principle is to use a dispersive lens group to cause the light source light to be dispersed after being focused by the dispersive lens group, forming a continuous monochromatic light focus on the optical axis with different distances from the dispersive lens group, thus establishing a wavelength and Based on the linear relationship of the axial distance, the corresponding position information is obtained by using the spectral information reflected by the surface of the object to be measured.

Figure 1 shows an existing spectral confocal measurement device. Light is emitted from the light source 1', enters the coupling part 2', and then passes to the sampling part 3', and then is projected to the measured object 4'. The reflected light carrying measurement information is formed on the surface and then returns to the coupling part 2' along the original optical path. After part or all of the reflected light passes through the spectroscopic part 5', it is finally converted into an electrical signal by the sensing part 6', so as to Parse and obtain position measurement results. This kind of measurement device uses single-point spectral confocal detection, and can only obtain height information of one object point at a time. If you want to obtain the position and height information of the entire surface, you need to scan in two directions, resulting in low sampling efficiency. Moreover, the reflected light returns to the light aperture in the opposite direction along the incident light path, causing stray light to appear in the spectrum received by the light aperture, thereby reducing the signal-to-noise ratio of the device and affecting the measurement accuracy.

Therefore, an improved spectral confocal measurement device is urgently needed to overcome the above defects.

Application content

One purpose of this application is to provide a spectral confocal measurement device to improve sampling efficiency, improve signal-to-noise ratio, and ultimately improve measurement accuracy.

In order to achieve the above object, the present application provides a spectral confocal measurement device, which includes a light source component for emitting incident light, an optical sampling part and a measurement part connected to the light source component, characterized in that: the optical sampling part includes A light entrance aperture, a light exit aperture and a dispersion lens group, the light source assembly and the optical sampling part are configured so that the incident light enters the first side of the dispersion lens group from the light entrance aperture in the form of a linear light source And focused on different measurement surfaces of the object to be measured, the second side of the dispersion lens group outputs reflected light, and the reflected light enters the measurement part through the light outlet to obtain the measurement result, wherein the first side There is no overlap with the second side.

Optionally, the light exit hole and the light entrance hole are the same light hole, and the light hole is located between the light source assembly and the dispersion lens group.

As a preferred embodiment, the light source assembly includes a light source, a first optical fiber group, optical fiber couplers respectively connected to the first optical fiber group, and a first linear optical fiber bundler. The first linear optical fiber bundler is located at A side between the light hole and the light source is used to allow the incident light to enter the dispersive lens group in the form of a linear light source.

Optionally, the light hole is a slit or a pin hole.

Preferably, the reflected light enters the measurement part in the form of a linear light source.

Preferably, a second optical fiber group and a second linear optical fiber bundler are provided between the optical hole and the measurement part, and the reflected light passes through the optical hole, the second optical fiber group and the second optical fiber bundle. A linear optical fiber bundle enters the measurement section.

Preferably, the plurality of optical fibers of the first optical fiber group are linearly arranged in the first linear optical fiber bundler; or the multiple optical fibers of the second optical fiber group are arranged in the second linear optical fiber bundler. Arranged in a linear format.

As another preferred embodiment, the light source assembly includes a light source and a focusing lens group located between the light source and the light aperture.

Optionally, the light emitted by the light source is a point light source or a linear light source.

Optionally, the first side of the dispersive lens group is the left or right side, and accordingly, the second side of the dispersive lens is the right side or left side that is opposite to and does not overlap the first side.

Optionally, the first side of the dispersive lens group is the central area, and the second side of the dispersive lens group is the surrounding area that does not overlap the central area; or the first side of the dispersive lens group is the surrounding area. area, the second side of the dispersive lens group is a central area that does not overlap with the surrounding areas.

Preferably, the light exit hole and the light entrance hole are light holes in different positions, the optical sampling part further includes a reflector located above the dispersion lens group, and the light entrance hole is located in the light source assembly. and the dispersion lens group, and the light exit hole is located between the reflector and the measurement part.

Preferably, the measurement part includes:

A spectrometer for receiving and processing the reflected light from the optical sampling part;

a sensor for converting the reflected light from the beam splitter into an electrical signal; and

A processor for calculating measurements based on the electrical signals from the sensor.

Preferably, the optical splitter includes:

A collimating mirror, used to collimate and refract the reflected light from the optical sampling part;

a diffraction grating for diffracting the reflected light from the collimating mirror; and

A focusing mirror is used to focus the diffracted reflected light onto the sensor.

Compared with the prior art, the incident light of the spectral confocal measurement device of the present application enters the first side of the dispersive lens group from the optical hole in the form of a line light source and focuses on different measurement surfaces of the object to be measured. The second side that does not overlap with the first side outputs reflected light, and the reflected light enters the measurement part through the light hole to obtain the measurement result. In other words, a line light source is used for spectral confocal detection, and a confocal line is obtained at one time Position information and height information of all points on the lens, so the sampling efficiency is greatly improved; moreover, light is incident from the first side of the dispersive lens group and reflected from the second side of the dispersive lens group. The incident and reflected optical paths do not overlap or are inverse. Thereby filtering the reflected light of non-focused wavelengths on the surface of the measured object, so that the spectral purity of the emitted light can be improved, thus improving the signal-to-noise ratio of the device and improving the measurement accuracy.

The present application will become clearer through the following description in conjunction with the accompanying drawings, which are used to explain embodiments of the present application.

Description of drawings

Figure 1 is a schematic structural diagram of a traditional spectral confocal measurement device.

Figure 2 is a schematic structural diagram of the first embodiment of the spectral confocal measurement device of the present application.

Figure 3 is a schematic structural diagram of a second embodiment of the spectral confocal measurement device of the present application.

Figure 4 is a schematic diagram of the arrangement of the optical fiber group of the spectral confocal measurement device of the present application.

Figure 5 is a schematic diagram of the connection between the second optical fiber group, the second linear optical fiber bundler and the measurement part of the spectral confocal measurement device of the present application.

Figure 6 is a schematic structural diagram of a third embodiment of the spectral confocal measurement device of the present application.

Figure 7 is a schematic structural diagram of the fourth embodiment of the spectral confocal measurement device of the present application.

Detailed ways

Several different preferred embodiments of the present application will be described below with reference to the accompanying drawings, wherein the same reference numerals in different figures represent the same components. As mentioned above, the essence of this application is to provide an improved spectral confocal measurement device to improve sampling efficiency, improve measurement accuracy, and reduce production costs.

Please refer to FIG. 2 . One embodiment of the spectral confocal measurement device 200 of the present application includes a light source component 210 , an optical sampling part 220 , and a measurement part 230 . The light source component 210 is used to emit a broad spectrum light beam with a certain wavelength range as incident light. The optical sampling part 220 includes an optical hole 221 for input and output light, and a dispersion lens group 222 for realizing dispersion of the light source. The light source assembly 210 and the optical sampling part 220 are configured so that the incident light enters the first side of the dispersive lens group 222 from the optical hole 221 in the form of a linear light source and focuses on different measurement surfaces of the object to be measured. The third side of the dispersive lens group 222 Reflected light is output from both sides, and the reflected light enters the measurement part 230 through the light hole 221 to obtain the measurement result.

It should be noted that the "first side" and "second side" referred to in this specification are two non-overlapping areas on the dispersion lens group, which can be the opposite left and right sides, or the center. area and surrounding area. In this embodiment, it can be understood as the left and right sides of the figure. The non-overlapping two side areas allow incident light and reflected light to pass through respectively to ensure that the incident light path and reflected light path passing through the dispersion lens group are completely different and do not overlap at all.

It should be noted that in this embodiment, the light exit hole and the light entrance hole are the same light hole 221, but this is not limited in other embodiments. Specifically, in the embodiment of FIG. 2 , the light source assembly 210 is encapsulated by the housing 210 a, which includes a light source 211 , a first optical fiber group 212 , an optical fiber coupler 213 respectively connected to the first optical fiber group 212 and a first wire. shaped optical fiber bundler 214. The first linear optical fiber bundler 214 is located between the optical hole 221 and the light source 211 to allow the incident light to enter one side of the dispersion lens group 222 in the form of a linear light source. Preferably, the light source 211 can be a wide spectrum white light LED light source, coupled to the first linear fiber bundler 214 and the first fiber group 212 through a fiber coupler 213 to integrate the incident light into a linear shape. More specifically, first linear optical fiber bundlers 214 are respectively provided at both ends of the first optical fiber group 212, and the plurality of optical fibers of the first optical fiber group 212 are linearly arranged in the first linear optical fiber bundler 214 (refer to Figure 4) , so that the incident light enters one side of the dispersion lens group 222 through the light hole 221 in the form of a linear light source. Optionally, at least one optical fiber may be provided in the first optical fiber group 212, or multiple optical fibers may be closely arranged in a linear or rectangular shape.

As shown in FIG. 2 , the optical sampling part 220 is enclosed by a housing 220 a and includes an optical hole 221 for input and output light, and a dispersion lens group 222 for realizing light source dispersion. Specifically, the optical hole 221 is provided on the housing 220a, and the dispersion lens group 222 is provided within the housing 220a. The light hole 221 serves as a light entrance hole and a light exit hole at the same time, and is respectively connected to the interfaces of the external first linear fiber bundler 214 and the second linear fiber bundler 261 to allow incident light and reflected light to pass through. The shape of the housing 220a of the optical sampling part 220 can be set according to actual needs and is not limited. Optionally, the light hole 221 can be implemented by a slit or a pin hole. It is preferred to adopt the form of slits to better filter out stray light.

Specifically, the light source assembly 210 reflects the measurement beam through the light source 211 and couples it to the first linear optical fiber bundler 214 through the optical fiber coupler 213. The light propagates in the optical fiber. The first linear optical fiber bundler is at the other end of the optical fiber group. 214, becoming a uniform linear light source; the measurement beam enters the inside of the housing of the optical sampling part 220 through the optical hole 221, and passes through the first side of the dispersion lens group 222 (the left side as shown in Figure 2, that is, the light only passes through One side enters the dispersion lens group 222), and is illuminated from the illumination surface measuring surface S provided at the front end of the housing. The dispersive lens group 222 is a lens involved in the spectral confocal sensor and produces axial chromatic aberration. Specifically, the dispersion lens group 222 focuses the light incident on the optical sampling part 220 at a focus position corresponding to the wavelength on the optical axis, so that the light beams of different wavelengths contained in the corresponding light source are converged to different focus positions. The light source includes continuous visible light beams in a certain wavelength range. For example, the three color light beams of red, green and blue are separated from each other and emitted from the illumination surface of the housing to the surface to be measured S. It should be noted that light of other colors and other wavelengths may also be emitted. .

The measurement beam is reflected by the surface S to be measured, passes through the dispersion lens group 222, and is emitted from the second side of the dispersion lens group 222 (i.e., the right side shown in Figure 2). Only the light focused on the surface of the object to be measured can pass through. The hole 221 propagates in the second optical fiber group 262 of the second linear bundler 261 (combined with FIG. 5 ), and the reflected light is collected into the measurement part 230 in the form of a linear light source. In this light path control method, only the light beam with a specific wavelength located on the confocal line can pass through the measurement surface and enter the dispersion lens group 222 and finally enter the measurement part 230 (imaging system) through the optical hole 221. The non-compliant light beam cannot enter the measurement part, so it is effective. Reduce the interference of other reflection wavelengths outside the confocal line, making the test more sensitive and improving the measurement accuracy. Of course, in other embodiments, light may be incident from the right side of the dispersive lens group 222 and emitted from the left side of the dispersive lens group 222 .

Specifically, in one embodiment, the measurement part 230 includes a spectrometer 240, a sensor 250, and a processor (not shown). The spectrometer 240 is used to receive and process the reflected light from the optical sampling part 220. The sensor 250 is used to convert the reflected light from the spectrometer 240 into an electrical signal. The processor is used to calculate the measurement result based on the electrical signal from the sensor 250. .

As a preferred embodiment, as shown in FIG. 2 , the beam splitter 240 includes a collimating mirror 241 , a diffraction grating 242 , and a focusing mirror 243 . The collimator 241 causes the measurement beam emitted from the light exit hole to be substantially collimated and irradiated onto the diffraction grating 242 . The diffraction grating 242 diffracts the substantially collimated irradiated measurement beam. The focusing mirror 243 images the diffracted light diffracted by the diffraction grating 242 on sensor 250. Typically, +1st order diffracted light is imaged on sensor 250, but other diffracted light, such as -1st order diffracted light, may also be imaged. It should be noted that the specific structure of the diffraction grating 242 is not limited. It should be noted that the focusing mirror 243 is a lens with small chromatic aberration, and can image the diffracted light on the sensor 250 regardless of the wavelength of the measurement light.

The specific structure of the sensor 250 is not limited. For example, a CMOS line sensor or an area array CCD line sensor can be used. The sensor 250 converts the measurement light into an electrical signal and transmits it to the processor. Based on the received signal (including X direction and Y direction), the processor can calculate the position information and height information of the object to be measured. As a result, this device can obtain the position information and height information of all points on a confocal line at one time, and only needs to perform one-dimensional scanning to obtain the position and height information of the entire measured object surface, thereby achieving efficient sampling. . The specific calculation method can refer to the existing technology and will not be described in detail here.

Figure 3 shows the second embodiment of the spectral confocal measurement device 300 of the present application. The difference between the device in this embodiment and the first embodiment lies in the light source assembly 310. The light source assembly 310 includes a light source 311 and a focusing lens group 312 located between the light source 311 and the optical hole 211 . The light source 311 may be a point light source or a linear light source, such as an LED light source, a laser, or other light sources such as mercury vapor. Specifically, the light source 311 emits a continuous visible light beam including different wavelengths from a blue wavelength range to a red wavelength range as a measurement light beam. After the measurement beam passes through the focusing lens group 312, the focused light enters the optical hole 211 in the form of a linear light source and then enters the dispersion lens group 212. Other optical paths, light measurement, etc. are the same as those in the first embodiment and will not be described again here.

Figure 6 shows the third embodiment of the spectral confocal measurement device 600 of the present application. The main difference between the device in this embodiment and the first and second embodiments lies in the incident light path and reflection light path of light passing through the dispersion lens group. In this embodiment, the incident light emitted by the light source assembly 610 enters the central area of the dispersion lens group 622 from the optical hole 621 in the form of a linear light source (the dotted line refers to the incident light path) and converges on different measurement surfaces of the object to be measured. The surrounding area of the lens group 622 outputs reflected light (the solid line indicates the outgoing light path), and the reflected light enters the measurement part 630 through the optical hole 621 to obtain the measurement result. Among them, the light source component 610 and the measurement part 630 can be selected from the first embodiment, the second embodiment, or the modifications of the first and second embodiments according to the actual situation. Linear optical fibers can also be used to transmit and/or receive light.

In addition, in another embodiment, the positions of the light source assembly 610 and the measurement part 630 in this embodiment can be replaced, that is, the incident light path passes through the surrounding area of the dispersion lens 622 (indicated by the solid line), and the outgoing light path It is the central area (indicated by the dotted line) passing through the dispersion lens group 622.

Figure 7 shows the fourth embodiment of the spectral confocal measurement device 700 of the present application. What is different from the above embodiment is that the light entrance hole 721 and the light exit hole 721' are different light holes and are respectively arranged at different positions of the dispersion lens group 722. In order to ensure the correct guidance of light, the optical sampling part also includes a reflecting mirror 725 located above the dispersion lens group 722 . The light entrance hole 721 is located between the light source assembly 710 and the dispersion lens group 722, and the light exit hole 721' is located between the reflector 725 and the measurement part 730. In this embodiment, the incident light emitted by the light source assembly 710 enters the surrounding area of the dispersion lens group 722 from the light entrance hole 721 in the form of a linear light source (the solid line refers to the incident light path) and converges on different measurement surfaces of the object to be measured. , the central area of the dispersive lens group 722 outputs reflected light (the dotted line indicates the output light path), and the reflected light passes through the light exit hole 721' through the reflector 725 and enters the measurement part 730 to obtain the measurement result. Among them, the light source component 710 and the measurement part 730 can be selected from the first embodiment, the second embodiment, or the modifications of the first and second embodiments according to the actual situation. Linear optical fibers can also be used to transmit and/or receive light.

In addition, in another embodiment, the positions of the light source assembly 710 and the measurement part 730 in this embodiment can be replaced, that is, the incident light path passes through the central area of the dispersion lens 722 (indicated by the dotted line), and the outgoing light path is Passing through the surrounding area of the dispersion lens group 722 (indicated by the solid line).

In summary, the incident light of the spectral confocal measurement device of the present application enters the first side of the dispersive lens group from the light entrance hole in the form of a linear light source and converges on different measurement surfaces of the object to be measured. The dispersive lens group does not overlap the first side of the dispersive lens group. The second side of one side outputs reflected light, and the reflected light enters the measurement part through the light outlet to obtain the measurement result. In other words, the spectral confocal detection is performed using a line light source, and the measurements of all points on a confocal line are obtained at one time. position information and height information, so the sampling efficiency is greatly improved; moreover, light is incident from the first side of the dispersive lens group and reflected from the second side of the dispersive lens group. The incident light path and the reflection light path do not overlap or are inverse, thus filtering the target The reflected light of non-focused wavelengths on the surface of the measuring object improves the spectral purity of the emitted light, thereby improving the signal-to-noise ratio of the device and improving the measurement accuracy. Furthermore, the device has a simple structure and reduces production costs.

The above disclosures are only preferred embodiments of the present application. Of course, they cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the patent scope of the present application are still within the scope of the present application.

Claims (14)

A spectral confocal measurement device, including a light source component for emitting incident light, an optical sampling part and a measurement part connected to the light source component, characterized in that: the optical sampling part includes a light entrance hole, a light exit hole and a dispersion The lens group, the light source assembly and the optical sampling part are configured so that the incident light enters the first side of the dispersion lens group from the light entrance hole in the form of a linear light source and focuses on different parts of the object to be measured. The measurement surface, the second side of the dispersion lens group outputs reflected light, and the reflected light enters the measurement part through the light outlet to obtain the measurement result, wherein the first side and the second side do not exist overlapping. The spectral confocal measurement device according to claim 1, wherein the light exit hole and the light entrance hole are the same light hole, and the light hole is located between the light source component and the dispersion lens group. The spectral confocal measurement device according to claim 2, wherein the light source assembly includes a light source, a first optical fiber group, an optical fiber coupler respectively connected to the first optical fiber group, and a first linear optical fiber bundler. , the first linear optical fiber bundler is located between the light entrance hole and the light source to allow the incident light to enter one side of the dispersive lens group in the form of a linear light source. The spectral confocal measurement device according to claim 1, wherein the light entrance hole and the light exit hole are slits or pin holes. The spectral confocal measurement device according to claim 1, wherein the reflected light enters the measurement part in the form of a linear light source. The spectral confocal measurement device according to claim 5, characterized in that: a second optical fiber group and a second linear fiber bundle are provided between the light outlet and the measurement part, and the reflected light passes through the light outlet. The hole and the second optical fiber group and the second linear optical fiber bundle enter the measurement part. The spectral confocal measurement device according to claim 3 or 6, characterized in that: the plurality of optical fibers of the first optical fiber group are linearly arranged in the first linear optical fiber bundler; or the second optical fiber The plurality of optical fibers of the group are linearly arranged in the second linear optical fiber bundler. The spectral confocal measurement device according to claim 1, wherein the light source assembly includes a light source and a focusing lens group located between the light source and the light entrance aperture. The spectral confocal measurement device according to claim 3 or 8, characterized in that: the light emitted by the light source is a point light source or a line light source. The spectral confocal measurement device according to claim 1, characterized in that: the first side of the dispersive lens group is on the left or right side, and correspondingly, the second side of the dispersive lens is opposite to and does not overlap. on the right or left side of said first side. The spectral confocal measurement device of claim 1, wherein the first side of the dispersive lens group is a central area, and the second side of the dispersive lens group is a surrounding area that does not overlap the central area. ; Or the first side of the dispersive lens group is the surrounding area, and the second side of the dispersive lens group is the central area that does not overlap the surrounding area. The spectral confocal measurement device according to claim 11, wherein the light exit aperture and the light entrance aperture are light apertures at different positions, and the optical sampling part further includes a lens located above the dispersion lens group. Reflector, the light entrance hole is located between the light source assembly and the dispersion lens group, and the light exit hole is located between the reflector and the measurement part. The spectral confocal measurement device according to claim 1, wherein the measurement part includes: A spectrometer for receiving and processing the reflected light from the optical sampling part; a sensor for converting the reflected light from the beam splitter into an electrical signal; and A processor for calculating measurements based on the electrical signals from the sensor. The spectral confocal measurement device according to claim 13, characterized in that: the spectrometer includes: A collimating mirror, used to collimate and refract the reflected light from the optical sampling part; a diffraction grating for diffracting the reflected light from the collimating mirror; and A focusing mirror is used to focus the diffracted reflected light onto the sensor.

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