Spectral confocal displacement sensor, calibration method and image restoration algorithm

Abstract

The embodiment of the invention provides a spectral confocal displacement sensor, a calibration method and an image restoration algorithm. The spectrum confocal displacement sensor comprises a light source module, an illumination module and a dispersion module which are arranged along a first direction, the light source module comprises a point light source and a line light source, light paths of the point light source and the line light source on a first plane do not comprise overlapped parts, and the first plane is perpendicular to the first direction; the point light source is used for emitting a first beam. The line light source is used for emitting a second beam. The illumination module is located on the light path of the line light source and used for collimating the second light beam and transmitting the collimated second light beam to the dispersion module; the dispersion module is used for carrying out dispersion on the first light beam and the second light beam passing through the illumination module and forming displacement wavelength codes on an optical axis; the dispersion module is also used for receiving a reflected light beam reflected by the test sample and transmitting the reflected light beam to the spectrum module; the spectrum module is used for generating spectrum images according to the reflected light beams, wherein the spectrum images comprise point spectrum images and line spectrum images.

Description

Technical Field

[0001] The present disclosure relates to the field of optical measurement, and in particular to a spectral confocal displacement sensor, a calibration method and an image restoration algorithm. Background Art

[0002] Two common devices in the field of optical measurement include point spectral confocal displacement sensors and line spectral confocal displacement sensors. The point spectral confocal displacement sensor can provide very accurate single-point measurement, but because the point spectral confocal displacement sensor is a single-point measurement, it takes a long time to measure the entire surface of an object, resulting in low sampling efficiency and slow operating speed. The line spectral confocal displacement sensor is a line measurement, which can quickly scan the entire surface of an object to improve measurement efficiency, but because the structure of the line spectral confocal displacement sensor is more complex and the algorithm processing is more complex, its measurement accuracy is lower.

[0003] Therefore, it is urgent to provide a spectral confocal displacement sensor that can solve the above problems. Summary of the invention

[0004] In view of this, embodiments of the present disclosure provide a spectral confocal displacement sensor, a calibration method, and an image restoration algorithm.

[0005] To achieve the above objectives, the technical solution of the present disclosure is implemented as follows:

[0006] In a first aspect, an embodiment of the present disclosure provides a spectral confocal displacement sensor, comprising: a light source module, an illumination module and a dispersion module arranged along a first direction; the light source module comprises a point light source and a line light source, the optical paths of the point light source and the line light source on a first plane do not include an overlapping portion, and the first plane is perpendicular to the first direction; the point light source is used to emit a first light beam, and the line light source is used to emit a second light beam; the illumination module is located on the optical path of the line light source, and is used to collimate the second light beam and transmit the collimated second light beam to the dispersion module; the dispersion module is used to disperse the first light beam and the second light beam passing through the illumination module to form a displacement wavelength code on the optical axis; the dispersion module is also used to receive a reflected light beam reflected by a test sample, and transmit the reflected light beam to the spectrum module; the spectrum module is used to generate a spectrum image according to the reflected light beam, and the spectrum image includes a point spectrum image and a line spectrum image.

[0007] In some embodiments, the dispersion module further includes an optical filter; the optical filter includes a hole passage and a slit passage, and the diameter of the hole in the hole passage is smaller than the width of the slit passage.

[0008] In some embodiments, the dispersion module includes a spectrometer and a dispersion objective lens; the spectrometer is used to split the first light beam and the second light beam, and transmit the split first light beam and the second light beam to the dispersion objective lens; the dispersion objective lens is used to disperse the split first light beam and the second light beam, and also to transmit the reflected light beam to the spectral module through the spectrometer.

[0009] In some embodiments, the lighting module includes a first collimating lens and a first focusing lens arranged along the first direction; the first collimating lens is used to collimate the second light beam; the first focusing lens is used to focus the collimated second light beam so that the focused light beam passes through the slit passage.

[0010] In some embodiments, the spectral module includes a second collimating lens, a reflection grating, a second focusing lens and an array detector; the second collimating lens is used to collimate the reflected light beam; the reflection grating is used to disperse the collimated reflected light beam into a spectrum of different wavelengths and reflect the spectrum to the second focusing lens; the second focusing lens is used to focus the spectrum onto the array detector; the array detector is used to detect the focused spectrum and generate the spectral image.

[0011] In some embodiments, the lighting module further includes an aperture, and the aperture is located between the first collimating lens and the first focusing lens; the aperture is used to filter the collimated second light beam and transmit the filtered second light beam to the first focusing lens.

[0012] In some embodiments, the hole passage comprises a plurality of holes; the plurality of holes are arranged along a direction parallel to the slit passage.

[0013] In a second aspect, an embodiment of the present disclosure provides a calibration method, which is applied to the spectral confocal displacement sensor in any of the above embodiments, and the method includes: determining a test line spectral image corresponding to a test sample; acquiring a standard point spectral image and a standard line spectral image corresponding to a standard sample; determining a calibration coefficient based on standard parameters corresponding to the standard point spectral image and the standard line spectral image; determining a test parameter based on the test line spectral image, and calibrating the test parameter based on the calibration coefficient.

[0014] In some embodiments, the calibration method further includes: setting a first threshold; obtaining an index of the test parameter, wherein the index is used to measure the discreteness of the test parameter; and determining that the test sample is abnormal when the index of the test parameter is greater than the first threshold.

[0015] In a third aspect, an embodiment of the present disclosure provides a line spectrum image restoration algorithm, which is applied to the spectral confocal displacement sensor in any of the above embodiments, and the algorithm includes: determining a test point spectrum image and a test line spectrum image corresponding to the test sample; diffusing the test point spectrum image according to a point source diffusion function; performing an inverse convolution operation on the diffused test point spectrum image and the test line spectrum image to determine a restored image corresponding to the test line spectrum image.

[0016] The disclosed embodiment provides a spectral confocal displacement sensor, a calibration method and an image restoration algorithm. The spectral confocal displacement sensor includes: a light source module, an illumination module and a dispersion module arranged along a first direction; the light source module includes a point light source and a line light source, the optical paths of the point light source and the line light source on the first plane do not include an overlapping part, and the first plane is perpendicular to the first direction; the point light source is used to emit a first light beam, and the line light source is used to emit a second light beam; the illumination module is located on the optical path of the line light source, and is used to collimate the second light beam and transmit the collimated second light beam to the dispersion module; the dispersion module is used to disperse the first light beam and the second light beam passing through the illumination module, and form a displacement wavelength encoding on the optical axis; the dispersion module is also used to receive a reflected light beam reflected by a test sample, and transmit the reflected light beam to the spectrum module; the spectrum module is used to generate a spectrum image according to the reflected light beam, and the spectrum image includes a point spectrum image and a line spectrum image. The disclosed embodiment integrates a point light source and a line light source in a spectral confocal displacement sensor. The point light source and the line light source share a set of dispersion modules and spectral modules to measure the test sample to generate a point spectrum image and a line spectrum image. This not only reduces the cost but also improves the measurement accuracy of the line spectrum image based on the point spectrum image. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a spectral confocal displacement sensor provided in an embodiment of the present disclosure;

[0018] Figure 2 A schematic top view of an optical filter provided by an embodiment of the present disclosure;

[0019] Figure 3 A schematic diagram of the steps of a calibration method provided in an embodiment of the present disclosure;

[0020] Figure 4a to Figure 4b The test line spectrum image and its corresponding restored image provided by the embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present disclosure and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0022] In the following description, a large number of specific details are given to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present disclosure, some technical features known in the art are not described; that is, all features of actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0023] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0024] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present disclosure necessarily has the first element, component, region, layer or part.

[0025] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0026] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present disclosure. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0027] In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present disclosure. The preferred embodiments of the present disclosure are described in detail below, but in addition to these detailed descriptions, the present disclosure may also have other implementations.

[0028] It should be noted that, for the convenience of description, various directions that may be used in the following description are first defined. The setting direction of the light source module, the illumination module, and the dispersion module is defined as a first direction (i.e., the Z direction in the accompanying drawings). The first plane is a plane perpendicular to the Z direction, and intersecting X and Y directions are defined in the first plane, and the X, Y, and Z directions may be perpendicular to each other.

[0029] In the related technology, a point spectrum confocal displacement sensor and a line spectrum confocal displacement sensor are used to measure the test sample twice, and the measurement result of the line spectrum confocal displacement sensor is corrected by the measurement result of the point spectrum confocal displacement sensor, thereby improving the measurement accuracy of the line spectrum confocal displacement sensor. However, there are problems such as large number of measurements, high cost, and high power consumption.

[0030] In view of this, Figure 1 The schematic diagram of the structure of a spectral confocal displacement sensor provided by the embodiment of the present disclosure is shown in FIG. Figure 1 As shown, the spectral confocal displacement sensor includes: a light source module 110, an illumination module 120 and a dispersion module 130 arranged along a first direction; the light source module 110 includes a point light source and a line light source, the optical paths of the point light source and the line light source on the first plane do not include an overlapping part, and the first plane is perpendicular to the first direction; the point light source is used to emit a first light beam, and the line light source is used to emit a second light beam; the illumination module 120 is located on the optical path of the line light source, and is used to collimate the second light beam and transmit the collimated second light beam to the dispersion module 130; the dispersion module 130 is used to disperse the first light beam and the second light beam passing through the illumination module 120, and form a displacement wavelength code on the optical axis; the dispersion module 130 is also used to receive a reflected light beam reflected by the test sample 140, and transmit the reflected light beam to the spectrum module 150; the spectrum module 150 is used to generate a spectrum image according to the reflected light beam, and the spectrum image includes a point spectrum image and a line spectrum image.

[0031] like Figure 1 As shown, the first light beam emitted by the point light source is transmitted to the dispersion module 130, the dispersion module 130 disperses the first light beam into lights of different wavelengths and focuses the lights of different wavelengths at different positions of the first optical axis to form a displacement wavelength encoding corresponding to the first light beam, and a certain wavelength of light is reflected by the test sample 140 to obtain a reflected light beam, which is transmitted by the dispersion module 130 to the spectrum module 150, and the spectrum module 150 generates a point spectrum image according to the reflected light beam.

[0032] Continue to refer Figure 1 , the second light beam emitted by the line light source is transmitted to the lighting module 120, the lighting module 120 collimates the second light beam and transmits it to the dispersion module 130, the dispersion module 130 disperses the collimated second light beam into lights of different wavelengths and focuses the lights of different wavelengths at different positions of the second optical axis to form a displacement wavelength encoding corresponding to the second light beam, a certain wavelength of light is reflected by the test sample 140 to obtain a reflected light beam, the reflected light beam is transmitted by the dispersion module 130 to the spectrum module 150, and the spectrum module 150 generates a line spectrum image according to the reflected light beam. Collimating the second light beam means adjusting the second light beam to be a parallel light beam.

[0033] In some embodiments, by using the spectral confocal displacement sensor provided in the embodiments of the present disclosure to measure a test sample, a point spectral image and a line spectral image of the test sample can be obtained simultaneously. This can improve the measurement accuracy of the line spectral image according to the point spectral image of the test sample, and there is no need to use two systems to perform point spectral measurement and line spectral measurement respectively, thereby reducing time cost and manufacturing cost. Compared with a single point spectral confocal displacement sensor or a line spectral confocal displacement sensor, the performance of the spectral confocal displacement sensor provided in the embodiments of the present disclosure is significantly improved.

[0034] In some embodiments, since the first light beam and the second light beam do not include an overlapping portion on the first plane, the first light beam and the second light beam can be respectively irradiated at different positions of the dispersion system, so that the first optical axis and the second optical axis do not overlap in space. Therefore, the displacement wavelength code corresponding to the first light beam and the unique wavelength code corresponding to the second light beam do not affect each other. The reflected light beam corresponding to the first light beam and the reflected light beam corresponding to the second light beam reflected by the test sample are refracted into the spectrum module at different positions of the dispersion system to generate a point spectrum image and a line spectrum image. In short, the process of generating a point spectrum image using a point light source is parallel to the process of generating a line spectrum image using a line light source.

[0035] In some embodiments, the dispersion module further includes an optical filter; the optical filter includes a hole passage and a slit passage, and the diameter of the hole in the hole passage is smaller than the width of the slit passage.

[0036] Figure 2 FIG. 1 is a top view schematic diagram of a filter provided by an embodiment of the present disclosure. Figure 2 As shown, the filter 131 includes a hole passage 1311 and a slit passage 1312. The hole passage 1311 is used to limit the size of the light spot output after the first light beam passes through, so as to reduce the stray light in the first light beam; the slit passage 1312 is used to limit the size of the light spot output after the second light beam output by the lighting module 120 passes through, so as to reduce the stray light in the second light beam. The diameter of the hole in the hole passage 1311 is smaller than the width of the slit passage 1312, so that the hole in the hole passage 1311 has a smaller size, and a smaller light spot can be formed on the test sample, thereby improving the resolution and measurement accuracy of the point spectrum image, so that the measurement accuracy of the line spectrum image can be better improved according to the point spectrum image of the test sample.

[0037] In some embodiments, the hole passage 1311 includes a plurality of holes; the plurality of holes are arranged along a direction parallel to the slit passage 1312 .

[0038] like Figure 2 As shown, the hole passage 1311 includes 8 holes, the length direction of the slit passage 1312 is parallel to the X direction, and the 8 holes in the hole passage 1311 are respectively arranged on both sides of the slit passage 1312 along two straight lines parallel to the X direction. In other embodiments, the hole passage can be arranged on only one side of the slit passage 1312.

[0039] In some embodiments, the projection of the light beam emitted by the point light source on the XOY plane overlaps with the projection of at least one hole in the hole passage, and the cross-sectional area of ​​the light beam emitted by the point light source on the XOY plane is slightly larger than or equal to the size of the hole, ensuring the light filtering effect of the hole passage. The projection of the light beam emitted by the line light source on the XOY plane overlaps with the projection of the slit passage, and the cross-sectional area of ​​the light beam emitted by the line light source on the XOY plane is slightly larger than or equal to the size of the slit passage, ensuring the light filtering effect of the slit passage.

[0040] In some embodiments, the number of point light sources is less than or equal to the number of holes in the hole passage, and the light beam emitted by each point light source passes through a hole in the hole passage, and the number of point spectrum images finally obtained is the same as the number of point light sources.

[0041] In some embodiments, the light emitted by the wide-spectrum LED light source passing through the small hole can be approximately regarded as a point light source, and the light emitted by the wide-spectrum LED light source passing through the slit can be approximately regarded as a line light source. Therefore, the wide-spectrum LED light source and the aperture with small holes and slits can be used to realize the integration of point light sources and line light sources. The distribution and size of the small holes and slits in the aperture can be the same as the distribution and size of the hole passage and the slit passage in the filter. It should be noted that Figure 2 The number of holes in the hole passage 1311 illustrated in the figure is only an exemplary description, and the present disclosure does not specifically limit the number of holes in the hole passage 1311.

[0042] In some embodiments, the lighting module 120 includes a first collimating lens 121 and a first focusing lens 122 arranged along a first direction; the first collimating lens 121 is used to collimate the second light beam; the first focusing lens 122 is used to focus the collimated second light beam so that the focused light beam passes through the slit passage 1312.

[0043] In some embodiments, due to the poor directivity of the second light beam emitted by the line light source, the dispersion effect is poor when passing through the dispersion module, and additional aberrations and distortions may also be generated. The second light beam is collimated by the first collimating lens 121 to be converted into a parallel light beam, so as to avoid the accuracy and clarity of the line spectrum image being affected by the poor directivity of the second light beam, so that a more accurate line spectrum image can be obtained. The collimated second light beam is focused by the first focusing lens 122, and the collimated second light beam is adjusted to a small light beam so that it can pass through the slit passage 1312, ensuring that a light beam of sufficient intensity passes through the slit passage 1312, thereby improving the utilization rate of the light source and the measurement accuracy of the spectral confocal displacement sensor.

[0044] It should be noted that the first focusing lens 122 may be a cylindrical focusing lens.

[0045] In some embodiments, the lighting module 120 further includes an aperture 123 , which is located between the first collimating lens 121 and the first focusing lens 122 ; the aperture 123 is used to filter the collimated second light beam and transmit the filtered second light beam to the first focusing lens 122 .

[0046] In some embodiments, the aperture 123 is used to filter out stray light (light that is not completely collimated) at the edge of the collimated second light beam to prevent the stray light from affecting the line spectrum image and thus affecting the measurement accuracy.

[0047] In some embodiments, the first collimating lens 121, the aperture 123 and the first focusing lens 122 share a common optical axis.

[0048] It should be noted that the aperture 123 may be a rectangular aperture.

[0049] In some embodiments, the dispersion module 130 includes a beam splitter 132 and a dispersion objective lens 133; the beam splitter 132 is used to split the first light beam and the second light beam, and transmit the split first light beam and the second light beam to the dispersion objective lens 133; the dispersion objective lens 133 is used to disperse the split first light beam and the second light beam, and also to transmit the reflected light beam to the spectrum module 150 through the beam splitter 132.

[0050] like Figure 1 As shown, the first light beam is transmitted to the beam splitter 132 through the hole passage, the first light beam is irradiated on the first surface of the beam splitter, and is divided into a reflection component and a transmission component by the beam splitter 132, wherein the reflection component is reflected away from the first surface of the beam splitter 132, and the transmission component passes through the beam splitter 132 and is transmitted to the dispersion objective lens 133, and the dispersion objective lens 133 disperses the transmission component in the first light beam to form a displacement wavelength encoding corresponding to the first light beam. A certain wavelength of light among the multiple wavelengths of light obtained by the dispersion of the transmission component in the first light beam is reflected by the test sample to obtain a reflected light beam, and the reflected light beam passes through the dispersion objective lens 133 and the beam splitter 132 in sequence, and is refracted by the second surface of the beam splitter 132 to the spectrum module 150.

[0051] Continue to refer Figure 1 , the second light beam collimated by the illumination module 120 is transmitted to the first surface of the beam splitter 132 through the slit passage, and is divided into a reflection component and a transmission component by the beam splitter 132, wherein the reflection component is reflected from the first surface of the beam splitter 132, and the transmission component is transmitted through the beam splitter 132 to the dispersion objective lens 133, and the dispersion objective lens 133 disperses the transmission component in the second light beam to form a displacement wavelength encoding corresponding to the second light beam. A certain wavelength of light among the multiple wavelengths of light obtained by the dispersion of the transmission component in the second light beam is reflected by the test sample to obtain a reflected light beam, which passes through the dispersion objective lens 133 and the beam splitter 132 in sequence, and is refracted by the second surface of the beam splitter 132 to the spectrum module 150.

[0052] It should be noted that the surface of the beam splitter close to the filter is the first surface, and the first surface of the beam splitter is coated with a beam splitter film to achieve light beam separation. The surface of the beam splitter close to the dispersive objective lens is the second surface, and the second surface of the beam splitter is coated with an anti-reflection film to reduce the reflection loss when the reflected light beam enters the second surface, so that most of the light in the reflected light beam can be refracted by the second surface into the spectral module, wherein the first surface and the second surface are two opposite surfaces.

[0053] In some embodiments, the spectral module 150 includes a second collimating lens 151, a reflection grating 152, a second focusing lens 153 and an array detector 154; the second collimating lens 151 is used to collimate the reflected light beam; the reflection grating 152 is used to disperse the collimated reflected light beam into a spectrum of different wavelengths and reflect the spectrum to the second focusing lens 153; the second focusing lens 153 is used to focus the spectrum onto the array detector 154; the array detector 154 is used to detect the focused spectrum and generate a spectral image.

[0054] In some embodiments, the spectrometer 132 refracts the reflected light beam to the incident portion 155 of the spectral module 150, and the second collimating lens 151 collimates the reflected light beam passing through the incident portion 155 to ensure that the reflected light beam can be transmitted to the reflection grating 152, and the reflection grating 152 disperses the collimated reflected light beam into spectra of different wavelengths, and the spectra of different wavelengths are focused on the array detector 154 through the second focusing lens 153.

[0055] In some embodiments, the incident portion 155 may include small holes and slits, which may be used to remove stray light around the reflected light beam. The distribution and size of the small holes and slits in the incident portion 155 may be the same as the distribution and size of the hole passage and the slit passage in the filter, thereby ensuring that each reflected light beam can enter the spectral module 150 through the corresponding channel.

[0056] It should be noted that the second focusing lens may be a spherical focusing lens.

[0057] The embodiments of the present disclosure also provide a calibration method, which is applied to the spectral confocal displacement sensor in any of the above embodiments. The calibration method includes: determining a test line spectral image corresponding to a test sample; acquiring a standard point spectral image and a standard line spectral image corresponding to a standard sample; determining a calibration coefficient according to standard parameters corresponding to the standard point spectral image and the standard line spectral image; determining a test parameter according to the test line spectral image, and calibrating the test parameter according to the calibration coefficient.

[0058] Figure 3 A schematic diagram of the steps of a calibration method provided in an embodiment of the present disclosure. Figure 3As shown, the calibration method includes the following steps:

[0059] Step 310: Determine the test line spectrum image corresponding to the test sample.

[0060] Step 320: Obtain a standard point spectrum image and a standard line spectrum image corresponding to the standard sample.

[0061] Step 330: Determine the calibration coefficient according to the standard parameters corresponding to the standard point spectrum image and the standard line spectrum image.

[0062] Step 340: Determine test parameters according to the test line spectrum image, and calibrate the test parameters according to the calibration coefficient.

[0063] In some embodiments, step 310 specifically includes: using the spectral confocal displacement sensor in the embodiments of the present disclosure to measure the test sample to obtain a test line spectral image corresponding to the test sample.

[0064] Step 320 specifically includes: using the spectral confocal displacement sensor in the embodiment of the present disclosure to measure the standard sample to obtain a standard point spectrum image and a standard line spectrum image corresponding to the standard sample.

[0065] Step 330 specifically includes: using spectral analysis technology to perform spectral analysis on the standard point spectrum image and the standard line spectrum image to determine the point spectrum standard parameters and line spectrum standard parameters corresponding to the standard sample, and the calibration coefficient is the ratio of the point spectrum standard parameter to the line spectrum standard parameter.

[0066] Step 340 specifically includes: using spectral analysis technology to perform spectral analysis on the test line spectral image to determine the test parameters of the test sample, and calibrating the test parameters according to the calibration coefficient to obtain the target parameters of the test sample, where the target parameters are the product of the test parameters and the calibration coefficient.

[0067] It should be noted that the test samples and standard samples include transparent or translucent samples, such as plastic panels or glass panels. The test parameters may include parameters such as the thickness or height of the test samples, and the standard parameters may include parameters such as the thickness or height of the standard samples.

[0068] In a specific embodiment, a standard sample group with thicknesses of 1 μm, 2 μm, ..., N μm is selected, and the spectral confocal displacement sensor in the embodiment of the present disclosure is used to measure the standard sample group to obtain a standard point spectrum image group and a standard line spectrum image group corresponding to the standard sample group. The standard point spectrum image group and the standard line spectrum image group are spectrally analyzed using spectral analysis technology to determine a point spectrum standard parameter group and a line spectrum standard parameter group.

[0069] The spectral confocal displacement sensor in the embodiment of the present disclosure is used to measure a test sample with a preset thickness of xμm, obtain a line spectrum image corresponding to the test sample, and use spectral analysis technology to perform spectral analysis on the test line spectrum image to determine the test parameters of the test sample. If the preset thickness xμm is the same as the thickness of a standard sample in the standard sample group, the test parameters are calibrated according to the ratio of the point spectrum standard parameter to the line spectrum standard parameter of the standard sample as the calibration coefficient; if the preset thickness xμm is different from the thickness of each standard sample in the standard sample group, the test parameters are calibrated according to the ratio of the mean square deviation of the point spectrum standard parameter group to the mean square deviation of the line spectrum standard parameter group as the calibration coefficient.

[0070] In other embodiments, if the preset thickness x μm is the same as the thickness of a standard sample in the standard sample group, the test parameters may be calibrated using the ratio of the mean square error of the point spectrum standard parameter group to the mean square error of the line spectrum standard parameter group as a calibration coefficient.

[0071] In other embodiments, if the preset thickness x μm is different from the thickness of each standard sample in the standard sample group, the test parameters may be calibrated according to the ratio of the point spectrum standard parameter to the line spectrum standard parameter of any standard sample as the calibration coefficient.

[0072] In some embodiments, when measuring the test sample, the calibration coefficient may be used to perform real-time calibration on the measurement parameters corresponding to each position of the test sample.

[0073] In the disclosed embodiment, the calibration coefficient is not limited to the ratio of the mean square error of the point spectrum standard parameter group to the mean square error of the line spectrum standard parameter group, as long as it is the calibration coefficient determined by the point spectrum standard parameters and the line spectrum standard parameters of the standard sample.

[0074] It should be noted that the present disclosure does not impose any restriction on the number of standard samples in the standard sample group.

[0075] In some embodiments, the calibration method further includes: setting a first threshold; obtaining an index of a test parameter, wherein the index is used to measure the degree of discreteness of the test parameter; and determining that an abnormality exists in the test sample when the index of the test parameter is greater than the first threshold.

[0076] In some embodiments, the test parameters corresponding to each position of the test sample scanned by the spectral confocal displacement sensor can be obtained according to the line spectrum image, and the index of the test parameter can be calculated. The index of the test parameter can be a standard deviation. If the index of the test parameter is greater than a first threshold, the discrete degree of the test sample is large, and it is determined that the test sample is abnormal. In a specific embodiment, if the standard deviation of the test sample with a preset thickness of xμm is greater than the first threshold, the test sample has problems such as uneven surface and inconsistent thickness.

[0077] The calibration method provided in the embodiment of the present disclosure can be used to perform random inspections on products and monitor the product qualification rate.

[0078] In some embodiments, the indicator of the test parameter may be any one of the indicators such as variance, range or coefficient of variation.

[0079] The disclosed embodiments also provide a line spectrum image restoration algorithm, which is applied to the spectral confocal displacement sensor in any of the above embodiments. The algorithm includes: determining a test point spectrum image and a test line spectrum image corresponding to a test sample; diffusing the test point spectrum image according to a point source diffusion function; performing an inverse convolution operation on the diffused test point spectrum image and the test line spectrum image to determine a restored image corresponding to the test line spectrum image.

[0080] In some embodiments, the spectral confocal displacement sensor provided by the embodiments of the present disclosure is used to measure the test sample to obtain a test point spectral image and a test line spectral image corresponding to the test sample; the test point spectral image is diffused according to a point spread function (PSF) to diffuse the test point spectral image into a 10×10 point spread image, and the point spread image and the test line spectral image are used as deconvolution kernels and feature maps to perform deconvolution operations, respectively, to determine a restored image corresponding to the test line spectral image.

[0081] In some embodiments, the test point spectrum image may also be diffused into point diffusion images of other sizes according to the point spread function, and the present disclosure does not impose any limitation on this.

[0082] Figure 4a to Figure 4b The test line spectrum image and its corresponding restored image provided by the embodiment of the present disclosure. Figures 4a to 4b As shown, the test line spectrum image has the problems of blurring and high noise, and the line spectrum 411 in the test line spectrum image is relatively flat, and the peak value 412 determined by the peak finding algorithm has low precision; while the restored image determined by the restoration algorithm has better image quality, and the line spectrum 421 in the restored image is steeper, and the peak value 422 determined by the peak finding algorithm has high precision and is more accurate.

[0083] In some embodiments, when determining the test parameters based on the test line spectral image, the peak value of the test line spectral image is particularly important. The restoration algorithm provided in accordance with the embodiment of the present disclosure can obtain a restored image with a more obvious peak value, which can more accurately determine the test parameters and further improve the measurement accuracy of the spectral confocal displacement sensor.

[0084] The embodiment of the present disclosure provides a spectral confocal displacement sensor, a calibration method and an image restoration algorithm. The spectral confocal displacement sensor includes: a light source module, an illumination module and a dispersion module arranged along a first direction; the light source module includes a point light source and a line light source, the optical paths of the point light source and the line light source on the first plane do not include an overlapping part, and the first plane is perpendicular to the first direction; the point light source is used to emit a first light beam, and the line light source is used to emit a second light beam; the illumination module is located on the optical path of the line light source, and is used to collimate the second light beam and transmit the collimated second light beam to the dispersion module; the dispersion module is used to disperse the first light beam and the second light beam passing through the illumination module, and form a displacement wavelength encoding on the optical axis; the dispersion module is also used to receive a reflected light beam reflected by a test sample, and transmit the reflected light beam to a spectrum module; the spectrum module is used to generate a spectrum image according to the reflected light beam, and the spectrum image includes a point spectrum image and a line spectrum image. The embodiment of the present disclosure integrates a point light source and a line light source in the spectral confocal displacement sensor, and the point light source and the line light source share a set of dispersion modules and spectrum modules to measure the test sample to generate a point spectrum image and a line spectrum image, which not only reduces the cost, but also can improve the measurement accuracy of the line spectrum image based on the point spectrum image.

[0085] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0086] The above description is only a preferred embodiment of the present disclosure, and does not limit the patent scope of the present disclosure. All equivalent structural changes made by using the contents of the present disclosure and the drawings under the inventive concept of the present disclosure, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present disclosure.

Claims

1. A spectral confocal displacement sensor, characterized in that: include: A light source module, an illumination module and a dispersion module arranged along a first direction; The light source module includes a point light source and a line light source, the light paths of the point light source and the line light source on a first plane do not include an overlapping portion, and the first plane is perpendicular to the first direction; the point light source is used to emit a first light beam, and the line light source is used to emit a second light beam; The lighting module is located on the optical path of the linear light source, and is used to collimate the second light beam and transmit the collimated second light beam to the dispersion module; The dispersion module is used to disperse the first light beam and the second light beam passing through the illumination module to form a displacement wavelength encoding on the optical axis; the dispersion module is also used to receive a reflected light beam reflected by the test sample and transmit the reflected light beam to the spectrum module; The spectrum module is used to generate a spectrum image according to the reflected light beam, and the spectrum image includes a point spectrum image and a line spectrum image.

2. The spectral confocal displacement sensor according to claim 1, characterized in that: The dispersion module also includes an optical filter; The optical filter comprises a hole passage and a slit passage, and the diameter of the hole in the hole passage is smaller than the width of the slit passage.

3. The spectral confocal displacement sensor according to claim 1, characterized in that: The dispersion module includes a beam splitter and a dispersion objective lens; The beam splitter is used to split the first light beam and the second light beam, and transmit the split first light beam and the second light beam to the dispersive objective lens; The dispersive objective lens is used to disperse the first light beam and the second light beam after splitting, and is also used to transmit the reflected light beam to the spectrum module through the spectroscope.

4. The spectral confocal displacement sensor according to claim 2, characterized in that: The lighting module comprises a first collimating lens and a first focusing lens arranged along the first direction; The first collimating lens is used to collimate the second light beam; The first focusing lens is used to focus the collimated second light beam so that the focused light beam passes through the slit passage.

5. The spectral confocal displacement sensor according to claim 1, characterized in that: The spectrum module includes a second collimating lens, a reflection grating, a second focusing lens and an array detector; The second collimating lens is used to collimate the reflected light beam; The reflection grating is used to disperse the collimated reflected light beam into spectrums with different wavelengths, and reflect the spectrum to the second focusing lens; The second focusing lens is used to focus the spectrum onto the array detector; The array detector is used to detect the focused spectrum and generate the spectrum image.

6. The spectral confocal displacement sensor according to claim 4, characterized in that: The lighting module further comprises an aperture, wherein the aperture is located between the first collimating lens and the first focusing lens; The aperture is used to filter the collimated second light beam and transmit the filtered second light beam to the first focusing lens.

7. The spectral confocal displacement sensor according to claim 2, characterized in that: The aperture passage includes a plurality of apertures; The plurality of holes are arranged in a direction parallel to the slit passage.

8. A calibration method, characterized in that: Applied to the spectral confocal displacement sensor according to any one of claims 1 to 7, the method comprising: Determine the test line spectrum image corresponding to the test sample; obtain the standard point spectrum image and the standard line spectrum image corresponding to the standard sample; Determine a calibration coefficient according to standard parameters corresponding to the standard point spectrum image and the standard line spectrum image; A test parameter is determined according to the test line spectrum image, and the test parameter is calibrated according to the calibration coefficient.

9. The calibration method according to claim 8, characterized in that: The method further comprises: Setting a first threshold; Obtaining an index of the test parameter, wherein the index is used to measure the degree of dispersion of the test parameter; When the index of the test parameter is greater than the first threshold, it is determined that the test sample is abnormal.

10. A line spectrum image restoration algorithm, characterized in that: Applied to the spectral confocal displacement sensor according to any one of claims 1 to 7, the algorithm comprises: Determine a test point spectral image and a test line spectral image corresponding to the test sample; Diffusion of the test point spectral image according to a point source diffusion function; A deconvolution operation is performed on the diffused test point spectrum image and the test line spectrum image to determine a restored image corresponding to the test line spectrum image.

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