A reflectivity non-uniformity elimination system and method for parallel color confocal differential measurement

Abstract

The present invention relates to a system and method for eliminating reflectivity non-uniformity in parallel color confocal differential measurement, belonging to the technical field of confocal measurement. The system includes: a polychromatic light source, a collimating lens, a digital micromirror device, a first beam-splitting lens, a dispersion tube lens, an objective lens, a sample stage module, a second beam-splitting lens, a first filter turntable, a first filter, a first focusing lens, a pre-focus camera, a third beam-splitting lens, a second filter turntable, a second filter, a second focusing lens, a focal-plane camera, a third filter turntable, a third filter, a third focusing lens, a post-focus camera, and a processing unit. Based on the system for eliminating reflectivity non-uniformity in parallel color confocal measurement, by virtue of the multiplicative property of reflectivity, the influence of different reflectivities of the measured object on different wavelengths is eliminated using the spectral information in the focal plane, and the measurement error problem caused by different reflectivities in different wavelength bands during the parallel color confocal differential measurement process is removed, greatly improving the measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of confocal measurement, and in particular, to a system and method for eliminating non-uniform reflectivity in parallel color confocal differential measurement. Background Art

[0002] With the rapid development of technology and the continuous improvement of manufacturing technology, the measurement requirements for the surface topography of high-precision machined parts are developing towards higher horizontal and vertical measurement accuracies, larger measurement ranges, and faster measurement speeds. The parallel differential measurement method derived from confocal measurement technology has become a hot topic of current research. This parallel differential measurement method does not rely on axial tomography technology, avoids traditional axial scanning, and does not require lateral scanning, greatly improving the measurement efficiency. At the same time, to solve the problem of the small axial measurement range of the existing white light differential measurement technology, many scholars have proposed a differential method based on multi-terminal color narrow-band bands, using the axial dispersion distance between adjacent bands to increase the axial range of differential measurement. However, for the measured object of the same material, the reflectivity errors generated in different bands are different. Therefore, there are measurement errors caused by the surface reflectivity of the measured object during the actual measurement process. Summary of the Invention

[0003] The purpose of the present invention is to provide a system and method for eliminating non-uniform reflectivity in parallel color confocal differential measurement, so as to eliminate the measurement errors caused by the different surface reflectivities of the measured object during the parallel color confocal differential measurement process and improve the measurement accuracy.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] A system for eliminating non-uniform reflectivity in parallel color confocal differential measurement includes: a complex light source, a collimating lens, a digital micromirror device, a first beam-splitting lens, a dispersion tube lens, an objective lens, a sample stage module, a second beam-splitting lens, a first filter turntable, a first filter, a first focusing lens, a pre-focal plane camera, a third beam-splitting lens, a second filter turntable, a second filter, a second focusing lens, a focal plane camera, a third filter turntable, a third filter, a third focusing lens, a post-focal plane camera, and a processing unit;

[0006] The complex light source faces the collimating lens and the digital micromirror device on the same line; the collimating lens and the digital micromirror device are sequentially arranged on the emission light path of the complex light source; the first beam-splitting lens is arranged on the feedback light path of the digital micromirror device; the dispersion tube lens, the objective lens, and the sample stage module are sequentially arranged on the reflection light path of the first beam-splitting lens;

[0007] A single beam of complex-colored light emitted by the complex-colored light source passes through the collimating lens and reaches the digital micromirror device; the digital micromirror device modulates the single beam of complex-colored light into a parallel dot light array, and after the dot light array is reflected by the first beam-splitting lens, it passes through the dispersion tube lens and is dispersed into multiple single-band monochromatic lights; the multiple single-band monochromatic lights are converged by the objective lens onto the surface of the object to be measured on the stage module;

[0008] The objective lens, the dispersion tube lens, and the first beam-splitting lens are also sequentially arranged on the reflection optical path of the object to be measured; the second beam-splitting lens is arranged on the transmission optical path of the first beam-splitting lens; the first filter turntable, the first focusing lens, and the pre-focus camera are sequentially arranged on the reflection optical path of the second beam-splitting lens; the third beam-splitting lens is arranged on the transmission optical path of the second beam-splitting lens; the second filter turntable, the second focusing lens, and the focal-plane camera are sequentially arranged on the transmission optical path of the third beam-splitting lens; the third filter turntable, the third focusing lens, and the post-focus camera are sequentially arranged on the reflection optical path of the third beam-splitting lens; multiple first filter sheets are arranged on the first filter turntable; multiple second filter sheets are arranged on the second filter turntable; multiple third filter sheets are arranged on the third filter turntable; the processing unit is respectively communicatively connected to the pre-focus camera, the focal-plane camera, and the post-focus camera;

[0009] After being reflected by the surface of the object to be measured, the multiple single-band monochromatic lights sequentially pass through the objective lens, the dispersion tube lens, and the first beam-splitting lens, and then are split by the second beam-splitting lens; the monochromatic light reflected by the second beam-splitting lens is filtered by the first filter sheet on the first filter turntable and then converged by the first focusing lens onto the pre-focus camera; the monochromatic light transmitted by the second beam-splitting lens is split by the third beam-splitting lens; the monochromatic light transmitted by the third beam-splitting lens is filtered by the second filter sheet on the second filter turntable and then converged by the second focusing lens onto the focal-plane camera; the monochromatic light reflected by the third beam-splitting lens is filtered by the third filter sheet on the third filter turntable and then converged by the third focusing lens onto the post-focus camera.

[0010] Optionally, the objective lens, the dispersion tube lens, the first beam-splitting lens, the second beam-splitting lens, the third beam-splitting lens, the second filter turntable, the second focusing lens, and the focal-plane camera are all placed parallel to the stage module; the first filter turntable, the first focusing lens, the pre-focus camera, the third filter turntable, the third focusing lens, and the post-focus camera are all placed perpendicular to the stage module.

[0011] Optionally, the first filter, the second filter, and the third filter are all narrow-band filters; the filtering bands of multiple first filters are different; the filtering bands of multiple second filters are different; the filtering bands of multiple third filters are different.

[0012] Optionally, the first beam-splitting lens, the second beam-splitting lens, and the third beam-splitting lens adopt half-transmissive and half-reflective lenses.

[0013] Optionally, the first beam-splitting lens, the second beam-splitting lens, and the third beam-splitting lens adopt a combination of a polarizer and a polarization beam splitter.

[0014] Optionally, the object-carrying module is a three-dimensional moving object stage.

[0015] A method for eliminating non-uniform reflectivity in parallel color confocal differential measurement, which is applied to the system for eliminating non-uniform reflectivity in parallel color confocal measurement, and the method for eliminating non-uniform reflectivity in parallel color confocal differential measurement includes:

[0016] The processing unit acquires the light intensity information I of the surface reflectivity-uniform object collected by the pre-focus camera and the post-focus camera during the parallel color confocal differential measurement f0_λ1 and I f0_λ2 ;

[0017] Acquire the light intensity information I of the surface information of the object to be measured collected by the pre-focus camera and the post-focus camera during the parallel color confocal differential measurement Df1_λ1 and I Df2_λ2 ;

[0018] Acquire the light intensity information I of the positive focal plane collected by the focal plane camera when using the third filter with the same filtering band as the first filter and the second filter f1_λ1 and I f1_λ2 ;

[0019] According to the light intensity information I of the surface reflectivity-uniform object f0_λ1 and I f0_λ2 , the light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 , and the light intensity information I of the positive focal plane f1_λ1 and I f1_λ2 Rewrite the differential formula of the parallel color confocal differential measurement to obtain the rewritten differential formula of the parallel color confocal differential measurement;

[0020] Use the rewritten differential formula of the parallel color confocal differential measurement to calculate the axial light intensity difference curve;

[0021] Restore the three-dimensional information of the surface of the object to be measured according to the axial light intensity difference curve.

[0022] Optionally, the light intensity information I of the object with uniform surface reflectivity f0_λ1 and I f0_λ2 , the light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 and the light intensity information I of the orthographic plane f1_λ1 and I f1_λ2 Rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement, which specifically includes:

[0023] According to the light intensity information I of the object with uniform surface reflectivity f0_λ1 and I f0_λ2 , the light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 and the light intensity information I of the orthographic plane f1_λ1 and I f1_λ2 Rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement where Z is the axial height information.

[0024] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0025] The present invention provides a system and method for eliminating non-uniform reflectivity in parallel color confocal differential measurement. The system includes: a polychromatic light source, a collimating lens, a digital micromirror device, a first beam-splitting lens, a dispersive tube lens, an objective lens, a loading module, a second beam-splitting lens, a first filter turntable, a first filter, a first focusing lens, a pre-focal plane camera, a third beam-splitting lens, a second filter turntable, a second filter, a second focusing lens, a focal plane camera, a third filter turntable, a third filter, a third focusing lens, a post-focal plane camera, and a processing unit. Based on the system for eliminating non-uniform reflectivity in parallel color confocal measurement, by using the multiplicative property of reflectivity, the influence of different reflectivities of the object to be measured on different wavelengths is eliminated by using the spectral information of the focal plane, and the measurement error problem caused by different reflectivities in different wavelength bands during the parallel color confocal differential measurement process is removed, greatly improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 is a schematic structural diagram of a system for eliminating non-uniform reflectivity in parallel color confocal differential measurement according to the present invention;

[0028] Figure 2 It is a schematic structural diagram of the first filter turntable and the first filter;

[0029] Figure 3 It is a schematic structural diagram of the second filter turntable and the second filter;

[0030] Figure 4 It is a schematic structural diagram of the third filter turntable and the third filter. Specific embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] The purpose of the present invention is to provide a system and method for eliminating reflectivity non-uniformity in parallel color confocal differential measurement, so as to eliminate the measurement error caused by different surface reflectivities of the object to be measured during the parallel color confocal differential measurement process and improve the measurement accuracy.

[0033] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] Figure 1 It is a schematic structural diagram of a system for eliminating reflectivity non-uniformity in parallel color confocal differential measurement according to the present invention, as Figure 1 shown. The system for eliminating reflectivity non-uniformity in parallel color confocal differential measurement includes: a polychromatic light source 1, a collimating lens 2, a digital micromirror device 3, a first beam splitting lens 4, a dispersive tube lens 5, an objective lens 6, a carrier module 7, a second beam splitting lens 8, a first filter turntable 9, a first filter 10, a first focusing lens 11, a pre-focus camera 12, a third beam splitting lens 13, a second filter turntable 14, a second filter 15, a second focusing lens 16, a focal plane camera 17, a third filter turntable 18, a third filter 19, a third focusing lens 20, a post-focus camera 21 and a processing unit 22.

[0035] Specifically, the polychromatic light source 1 faces the collimating lens 2 and the digital micromirror device 3 on the same line; the collimating lens 2 and the digital micromirror device 3 are sequentially arranged on the emission optical path of the polychromatic light source 1. The polychromatic light source 1 is used to generate polychromatic light, including multiple wavelengths, such as short-wave wavelengths, central wavelengths, and long-wave wavelengths.

[0036] The first beam-splitting lens 4 is disposed on the feedback optical path of the digital micromirror device 3; the dispersion tube lens 5, the objective lens 6, and the sample stage module 7 are sequentially disposed on the reflection optical path of the first beam-splitting lens 4. The single beam of polychromatic light emitted by the polychromatic light source 1 passes through the collimating lens 2 and reaches the digital micromirror device 3; the digital micromirror device 3 modulates the single beam of polychromatic light into a parallel dot light array, and after the dot light array is reflected by the first beam-splitting lens 4, it passes through the dispersion tube lens 5 and is dispersed into multiple single-band monochromatic lights; the multiple single-band monochromatic lights are converged by the objective lens 6 onto the surface of the object to be measured (also referred to as the sample to be measured) on the sample stage module 7. Figure 1 shows the short-wave light focusing position 23, the center-wavelength light focusing position 24, and the long-wave light focusing position 25.

[0037] The objective lens 6, the dispersion tube lens 5, and the first beam-splitting lens 4 are also sequentially disposed on the reflection optical path of the object to be measured; the second beam-splitting lens 8 is disposed on the transmission optical path of the first beam-splitting lens 4; the first filter turntable 9, the first focusing lens 11, and the pre-focal plane camera 12 are sequentially disposed on the reflection optical path of the second beam-splitting lens 8; the third beam-splitting lens 13 is disposed on the transmission optical path of the second beam-splitting lens 8; the second filter turntable 14, the second focusing lens 16, and the focal plane camera 17 are sequentially disposed on the transmission optical path of the third beam-splitting lens 13; the third filter turntable 18, the third focusing lens 20, and the post-focal plane camera 21 are sequentially disposed on the reflection optical path of the third beam-splitting lens 13. The processing unit 22 is respectively communicatively connected to the pre-focal plane camera 12, the focal plane camera 17, and the post-focal plane camera 21.

[0038] Figure 2 is a schematic structural diagram of the first filter turntable and the first filter; see Figure 2 , a plurality of the first filters 10 are disposed on the first filter turntable 9. Figure 3 is a schematic structural diagram of the second filter turntable and the second filter; see Figure 3 , a plurality of the second filters 15 are disposed on the second filter turntable 14. Figure 4 is a schematic structural diagram of the third filter turntable and the third filter, see Figure 4, multiple pieces of the third filter 19 are arranged on the third filter turntable 18. The first filter 10, the second filter 15, and the third filter 19 are all narrowband filters; the filtering bands of multiple pieces of the first filter 10 are different but similar; similarly, the filtering bands of multiple pieces of the second filter 15 are different but similar; the filtering bands of multiple pieces of the third filter 19 are different but similar. It can be seen that the structures of the first filter turntable 9, the second filter turntable 14, and the third filter turntable 18 in the present invention are the same. By installing multiple narrowband filters with different but similar bands on the filter turntable, narrowband illumination light of different bands can be generated by selecting narrowband filters with different filtering bands on the filter turntable. The narrowband illumination light irradiates the surface of the object to be measured, and a narrowband light beam with a unique wavelength value λ is in a focused state at any optical axis axial height Z.

[0039] See Figure 1 , after the multiple single-band monochromatic lights are reflected by the surface of the object to be measured, they sequentially pass through the objective lens 6, the dispersion tube lens 5, and the first beam-splitting lens 4, and then are split by the second beam-splitting lens 8; the monochromatic light reflected by the second beam-splitting lens 8 is filtered by the first filter 10 on the first filter turntable 9 and then converged by the first focusing lens 11 to the pre-focal plane camera 12; the monochromatic light transmitted by the second beam-splitting lens 8 is split by the third beam-splitting lens 13; the monochromatic light transmitted by the third beam-splitting lens 13 is filtered by the second filter 15 on the second filter turntable 14 and then converged by the second focusing lens 16 to the focal plane camera 17; the monochromatic light reflected by the third beam-splitting lens 13 is filtered by the third filter 19 on the third filter turntable 18 and then converged by the third focusing lens 20 to the post-focal plane camera 21.

[0040] Among them, the objective lens 6, the dispersion tube lens 5, the first beam-splitting lens 4, the second beam-splitting lens 8, the third beam-splitting lens 13, the second filter turntable 14, the second focusing lens 16, and the focal plane camera 17 are respectively placed parallel to the carrier module 7. The first filter turntable 9, the first focusing lens 11, the pre-focal plane camera 12, the third filter turntable 18, the third focusing lens 20, and the post-focal plane camera 21 are respectively placed perpendicular to the carrier module 7.

[0041] In practical applications, the first beam-splitting lens, the second beam-splitting lens, and the third beam-splitting lens can adopt a semi-transmissive and semi-reflective lens, or a combination of a polarizer and a polarization beam splitter.

[0042] In practical applications, the carrier module can adopt an existing three-dimensional moving stage to drive the object to be measured to perform two-dimensional planar movement or three-dimensional spatial attitude movement.

[0043] In a reflectivity non-uniformity elimination system for parallel color confocal differential measurement according to the present invention, the polychromatic light emitted by the polychromatic light source 1 passes through the collimating lens 2 and then reaches the digital micromirror device 3. The digital micromirror device 3 reflects a dot light array, which passes through the first beam splitting lens 4, the dispersion tube lens 5 and the objective lens 3 and irradiates on the sample stage module 7. After being reflected by the sample stage module 7, it passes through the first beam splitting lens 4 again, and is split by the second beam splitting lens 8 and the third beam splitting lens 13. The monochromatic light beams after splitting are filtered by the first filter 10, the second filter 15 and the third filter 19 respectively, and then are converged by the first focusing lens 11, the second focusing lens 16 and the third focusing lens 20 and enter the pre-focus camera 12, the focal plane camera 17 and the post-focus camera 21 respectively. The processing unit 22 acquires the surface information of the measured sample collected by the pre-focus camera 12, the focal plane camera 17 and the post-focus camera 21, analyzes the acquired surface information of the measured object, and then compensates and eliminates the reflectivity non-uniformity error.

[0044] The process of the reflectivity non-uniformity elimination system for parallel color confocal differential measurement to acquire the surface information of the measured object is as follows:

[0045] A single beam of polychromatic light emitted by the polychromatic light source 1 passes through the collimating lens 2 and reaches the digital micromirror device 3. The digital micromirror device 3 modulates the single beam of polychromatic light into a parallel dot light array. The reflected dot light array passes through the first beam splitting lens 4 and then through the dispersion tube lens 5 and is dispersed into multiple single-band monochromatic lights, and then is converged by the objective lens 6 onto the surface of the measured sample on the sample stage module 7. After being reflected by the surface of the measured sample, it passes through the dispersion tube lens 5 and the first beam splitting lens 4, and is split by the second beam splitting lens 8 and the third beam splitting lens 13. The split light beams are filtered by the first filter 10, the second filter 15 and the third filter 19 respectively, and then are converged by the first focusing lens 11, the second focusing lens 16 and the third focusing lens 20 into the pre-focus camera 12, the focal plane camera 17 and the post-focus camera 21 respectively. The processing unit 22 analyzes the acquired surface information of the measured sample, and then compensates and eliminates the error caused by the non-uniformity of the anti-color rate collected in different bands. This can be achieved through the following process:

[0046] Using the pre-focus camera 12 and the post-focus camera 21 in the reflectivity non-uniformity elimination system for parallel color confocal differential measurement, measure the light intensity information I of a sample with uniform surface reflectivity in the spectral band used by them f0_λ1 and I f0_λ2 ;

[0047] Using the pre-focus camera 12 and the post-focus camera 21 in the reflectivity non-uniformity elimination system for parallel color confocal differential measurement, respectively obtain the light intensity information I of the surface information of the measured sample during the measurement process Df1_λ1 and I Df2_λ2At the same time, the focal plane camera 17 is used to obtain the light intensity information I of the positive focal plane using the third filter 19 with the same filter band as the first filter 10 and the second filter 15 f1_λ1 and I f1_λ2 ;

[0048] Because the sample reflectivity is not uniform, it is a multiplicative error. The color confocal differential measurement differential formula can be rewritten to change the original axial difference curve Z = I Df1_λ1 -I Df2_λ2 Rewrite as Where Z is the axial height information. Then for the λ1 wavelength data I collected by the pre-focus camera 12 Df1_λ1 The reflectivity is uneven, and the light intensity information I of the same band at the focal plane is removed. f1_λ1 And multiply it by the light intensity information I of the sample with uniform anti-color ratio at the focal plane f0_λ1 Similarly, the λ2 wavelength data I collected by the camera 21 after focusing Df2_λ2 The reflectivity is uneven, and the light intensity information I at the focal plane is removed. f1_λ2 And multiply it by the light intensity information I of the sample with uniform anti-color ratio at the focal plane f0_λ2 The amplitude is restored by a method; finally, the axial light intensity difference curve pre-calibrated with a sample with uniform reflectivity can be used to restore the three-dimensional information of the surface of the sample being tested.

[0049] It can be seen that the present invention proposes a system for eliminating uneven reflectivity in parallel color confocal differential measurement. Based on the connection relationship between the various components in the system, through the multiplicative characteristic of reflectivity, the focal plane spectral information can be used to eliminate the influence of different reflectivities of the measured sample on different wavelengths, thereby eliminating the measurement error problem caused by different reflectivities in different bands in the parallel color confocal differential measurement process, greatly improving the measurement accuracy, and having broad application prospects.

[0050] Based on the parallel color confocal measurement reflectivity uneven elimination system, the present invention also provides a parallel color confocal differential measurement reflectivity uneven elimination method, which specifically includes:

[0051] S1. The processing unit obtains the light intensity information I of the object with uniform surface reflectivity collected by the front-focus camera and the back-focus camera during the parallel color confocal differential measurement. f0_λ1 and I f0_λ2 ;

[0052] S2, obtaining the light intensity information I of the surface information of the measured object collected by the front-focus camera and the back-focus camera during the parallel color confocal differential measurement Df1_λ1 and I Df2_λ2 ;

[0053] S3. Obtain the light intensity information I of the positive focal plane collected when the focal plane camera uses a third filter with the same filter band as the first filter and the second filter. f1_λ1 and I f1_λ2 ;

[0054] S4. According to the light intensity information I of the surface reflectivity uniform object f0_λ1 and I f0_λ2 , the light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 , and the light intensity information I of the positive focal plane f1_λ1 and I f1_λ2 rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement where Z is the axial height information;

[0055] S5. Calculate the axial light intensity difference curve using the rewritten differential formula of color confocal differential measurement;

[0056] S6. Restore the three-dimensional information of the surface of the object to be measured according to the axial light intensity difference curve.

[0057] The axial light intensity difference curve is an existing measurement technique. In the present invention, by rewriting it, the measurement error caused by the uneven surface reflectivity of the sample to be measured in actual measurement is corrected, improving the measurement accuracy.

[0058] In the existing parallel color confocal differential measurement system, the axial light intensity difference curve calibrated with a sample with uniform reflectivity is Z = I Df1_λ1 -I Df2_λ2 , but strictly speaking, it should be Z = n1·I Df1_λ1 -n1·I Df2_λ2 , where n1 represents the reflectivity of the sample with uniform reflectivity. Since the value of n1 is 1, the collected light intensity signal is the error-free signal.

[0059] In actual measurement, the sample reflectivity is n2, and n2 is less than 1, that is, the signal collected in actual measurement is an interference signal, and the interference source is the sample surface reflectivity n2, that is, the differential signal should be expressed as At the same time, in the two-dimensional image, the n2 of the differential data collected at each different pixel point is different; I f1_λ1 , I f1_λ2 respectively represent the light intensity information of λ1 and λ2 at the positive focal position, and can be expressed as: I f1_λ1 = I f0_λ1 ·n2, I f1_λ2 = I f0_λ2·n2. Therefore, to eliminate the problem of uneven sample reflectivity, it is necessary to remove the interference of n2, but at the same time, information such as the slope of the original measurement curve cannot be changed (which will reduce the measurement accuracy and sensitivity). Therefore, the present invention transforms the formula Z = I Df1_λ1 -I Df2_λ2 into The influence of n2 is removed by taking the ratio, and information such as the slope of the curve is restored by multiplication.

[0060] The existing color confocal differential measurement method does not analyze the problem of uneven reflectivity generated in different bands. The reflectivity unevenness elimination system for parallel color confocal measurement of the present invention, by virtue of the multiplicative property of reflectivity, utilizes the focal plane spectral information to eliminate the influence of different reflectivities of the measured sample on different wavelengths, and removes the measurement error problem caused by different reflectivities in different bands during the parallel color confocal differential measurement process, greatly improving the measurement accuracy and having a wide range of application prospects.

[0061] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0062] Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the control method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, there will be changes in the specific implementation manner and application scope according to the idea of the present invention. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A reflectivity non-uniformity elimination system for parallel color confocal differential measurement, characterized in that Including: A composite light source, a collimating lens, a digital micromirror device, a first beam-splitting lens, a dispersion tube lens, an objective lens, a sample stage module, a second beam-splitting lens, a first filter turntable, a first filter, a first focusing lens, a pre-focus camera, a third beam-splitting lens, a second filter turntable, a second filter, a second focusing lens, a focal-plane camera, a third filter turntable, a third filter, a third focusing lens, a post-focus camera, and a processing unit; The composite light source faces the collimating lens and the digital micromirror device on the same line; the collimating lens and the digital micromirror device are sequentially arranged on the emission optical path of the composite light source; the first beam-splitting lens is arranged on the feedback optical path of the digital micromirror device; the dispersion tube lens, the objective lens, and the sample stage module are sequentially arranged on the reflection optical path of the first beam-splitting lens; A single beam of composite light emitted by the composite light source passes through the collimating lens and reaches the digital micromirror device; the digital micromirror device modulates the single beam of composite light into a parallel dot light array, and after the dot light array is reflected by the first beam-splitting lens, it passes through the dispersion tube lens and is dispersed into multiple single-band monochromatic lights; the multiple single-band monochromatic lights are converged by the objective lens onto the surface of the object to be measured on the sample stage module; The objective lens, the dispersion tube lens, and the first beam-splitting lens are also sequentially arranged on the reflection optical path of the object to be measured; the second beam-splitting lens is arranged on the transmission optical path of the first beam-splitting lens; the first filter turntable, the first focusing lens, and the pre-focus camera are sequentially arranged on the reflection optical path of the second beam-splitting lens; the third beam-splitting lens is arranged on the transmission optical path of the second beam-splitting lens; the second filter turntable, the second focusing lens, and the focal-plane camera are sequentially arranged on the transmission optical path of the third beam-splitting lens; the third filter turntable, the third focusing lens, and the post-focus camera are sequentially arranged on the reflection optical path of the third beam-splitting lens; multiple first filters are arranged on the first filter turntable; multiple second filters are arranged on the second filter turntable; multiple third filters are arranged on the third filter turntable; the processing unit is communicatively connected to the pre-focus camera, the focal-plane camera, and the post-focus camera respectively; After the multiple single-band monochromatic lights are reflected by the surface of the object to be measured, they sequentially pass through the objective lens, the dispersion tube lens, and the first beam-splitting lens, and then are split by the second beam-splitting lens; the monochromatic light reflected by the second beam-splitting lens is filtered by the first filter on the first filter turntable and then converged by the first focusing lens onto the pre-focus camera; the monochromatic light transmitted by the second beam-splitting lens is split by the third beam-splitting lens; the monochromatic light transmitted by the third beam-splitting lens is filtered by the second filter on the second filter turntable and then converged by the second focusing lens onto the focal-plane camera; the monochromatic light reflected by the third beam-splitting lens is filtered by the third filter on the third filter turntable and then converged by the third focusing lens onto the post-focus camera.

2. The reflectivity non-uniformity elimination system for parallel color confocal differential measurement according to claim 1, wherein The objective lens, the dispersion tube lens, the first beam-splitting lens, the second beam-splitting lens, the third beam-splitting lens, the second filter turntable, the second focusing lens, and the focal plane camera are all placed parallel to the sample stage module; The first filter turntable, the first focusing lens, the pre-focal camera, the third filter turntable, the third focusing lens, and the post-focal camera are all placed perpendicular to the sample stage module.

3. The reflectivity non-uniformity elimination system for parallel color confocal differential measurement according to claim 1, wherein The first filter, the second filter, and the third filter are all narrow-band filters; the filtering bands of multiple first filters are different; the filtering bands of multiple second filters are different; the filtering bands of multiple third filters are different.

4. The reflectivity non-uniformity elimination system for parallel color confocal differential measurement according to claim 1, characterized in that, The first beam-splitting lens, the second beam-splitting lens, and the third beam-splitting lens adopt semi-transparent and semi-reflective lenses.

5. The reflectivity non-uniformity elimination system for parallel color confocal differential measurement according to claim 1, characterized in that, The first beam-splitting lens, the second beam-splitting lens, and the third beam-splitting lens adopt a combination of a polarizer and a polarization beam splitter.

6. The reflectivity unevenness elimination system for parallel color confocal differential measurement according to claim 1, characterized in that, The sample stage module is a three-dimensional moving stage.

7. A method for eliminating reflectivity non-uniformity in parallel color confocal differential measurement, characterized in that, Applied to the reflectivity non-uniformity elimination system for parallel color confocal measurement according to any one of claims 1-6, the method for eliminating reflectivity non-uniformity in parallel color confocal differential measurement includes: The processing unit acquires the light intensity information I of a surface reflectance-uniform object collected by the pre-focus camera and the post-focus camera during the parallel color confocal differential measurement f0_λ1 and I f0_λ2 ; Obtain the light intensity information I of the surface information of the object to be measured collected by the pre-focus camera and the post-focus camera during the parallel color confocal differential measurement Df1_λ1 and I Df2_λ2 ; Obtain the light intensity information I of the positive focal plane collected when the focal plane camera uses a third filter with the same filter band as the first filter and the second filter f1_λ1 and I f1_λ2 ; According to the light intensity information I of the surface reflectivity uniform object f0_λ1 and I f0_λ2 、the light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 as well as the light intensity information I of the front focal plane f1_λ1 and I f1_λ2 Rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement; Calculating the axial light intensity difference curve by using the rewritten color confocal differential measurement differential formula; Restoring the three-dimensional information of the surface of the object to be measured according to the axial light intensity difference curve.

8. The method for eliminating reflectivity non-uniformity in parallel color confocal differential measurement according to claim 7, wherein The light intensity information I of the object with uniform surface reflectivity as described above f0_λ1 and I f0_λ2 、The light intensity information I of the surface information of the object to be measured Df1_λ1 and I Df2_λ2 And the light intensity information I of the orthographic plane f1_λ1 and I f1_λ2 Rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement, specifically including: According to the light intensity information I of the object with uniform surface reflectivity f0_λ1 and I f0_λ2 、the light intensity information I of the surface information of the object to be measured DF1_λ1 and I Df2_λ2 as well as the light intensity information I of the front focal plane f1_λ1 and I f1_λ2 rewrite the differential formula of color confocal differential measurement to obtain the rewritten differential formula of color confocal differential measurement where Z is the axial height information.

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