Optical phase shifting interferometric detection apparatus and method

Abstract

This invention provides an optical phase-shifting interferometry detection device and method, relating to the field of optical detection technology. The optical phase-shifting interferometry detection device includes a phase-shifting interferometry system and a spectral domain interferometry system. A moving platform is used to induce a small random displacement in a reference mirror or sample, introducing a randomly varying phase shift into the reference light and sample light. Simultaneously, the spectral domain interferometry system detects the overall vibration and random phase shift of the reference mirror or sample in the phase-shifting interferometry system. The obtained phase shift is used to calculate the optical path difference on the sample surface, thus obtaining the surface morphology of the sample.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to an optical phase-shifting interferometry detection device and method. Background Technology

[0002] The basic principle of phase-shifting interferometry (PSI) is to induce a phase shift between the sample light and the reference light using a phase shifter. Multiple interferograms are then captured using a camera, and phase information is obtained using a mathematical model. Piezoelectric ceramics (PZT) are commonly used phase-shifting devices. For PSI, the accuracy of the phase shift is the primary factor determining measurement precision. In PZT-based phase-shifting interferometry, the phase shifter needs rigorous calibration before measurement to ensure the accuracy of each phase shift. For larger aperture samples, multiple PZT phase shifters are often required. Furthermore, when the driven reference mirror or sample is large, the phase shift error of PZT is significant. Additionally, vibration or tilting of the reference mirror or sample during phase shifting can easily lead to larger phase shift errors, affecting measurement accuracy. Because precise control of the phase shift is required, the phase shift rate is relatively slow, making it susceptible to environmental interference. While the random phase-shift algorithm can theoretically eliminate the dependence on the phase shifter, it requires calculating the phase shift from the entire interferometric image, which involves a large amount of computation. Furthermore, the accuracy of the calculated phase shift is affected by factors such as the nonlinearity of the CCD detector, phase sign reversal, phase shift surface tilt caused by vibration, and non-uniformity of phase shift caused by air disturbance, thus reducing the measurement accuracy.

[0003] The patent "Synchronous Phase Shift Measurement System and Method Based on White Light Interference Spectroscopy" (CN201910395069.1) uses a polarization method to introduce spatial phase shift, analyzing two frames of spectral interference signals with a 90° phase difference to measure surface morphology. However, because the spectrometer in this patent can only acquire the interference spectrum of one point on the sample surface at each moment, it requires translating the sample to obtain the surface morphology distribution, which is relatively slow. The patent "A Phase Shift Interference Measurement System and its Waveplate Phase Shift Method" (CN201710533969.9) discloses a phase shift interferometric detection system that achieves arbitrary phase shift by adjusting the rotation angle of the waveplate. However, insufficient accuracy in angle measurement introduces phase shift errors, reducing detection accuracy. Furthermore, this patent cannot be used for opaque samples. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an optical phase-shifting interferometry detection device and method.

[0005] On the one hand, an optical phase-shifting interferometry detection device consists of two parts: a phase-shifting interferometry system and a spectral domain interferometry system;

[0006] The phase-shifting interferometry system includes: a laser source 1, a collimating lens 2, a beam splitter 3, a reference flat crystal 4, a sample 5, a first lens 6, an area array camera 7, a computer 19, a mobile platform 20, and a phase-shifting interferometry system probe light 24.

[0007] The laser source 1 emits a laser beam, which is collimated into a parallel beam by the collimating lens 2. The beam is reflected by the beam splitter 3 to form the phase-shifting interference system probe light 24. The phase-shifting interference system probe light 24 passes through the reference flat crystal 4 and illuminates the surface of the sample 5. The moving platform 20 drives the sample 5 to produce a small vertical displacement. The sample light reflected by the lower surface of the sample 5 and the reference light reflected by the upper surface of the reference flat crystal 4 pass through the beam splitter 3 and the first lens 6, forming an interference image at the area array camera 7. The area array camera 7 acquires the interference image and transmits it to the computer 19 for processing and display.

[0008] The spectral domain interferometry system includes: a low-coherence light source 8, an optical fiber circulator 9, a 1×3 coupler 10, a first collimator 11, a second collimator 12, a third collimator 13, a second lens 14, a third lens 15, a fourth lens 16, a reference object 17, a spectrometer 18, a first spectral domain interferometry system probe beam 21, a second spectral domain interferometry system probe beam 22, and a third spectral domain interferometry system probe beam 23;

[0009] The low-coherence light source 8 emits light, which enters the fiber optic circulator 9 and then the 1×3 coupler 10, where it is split into three beams. These beams pass through the first collimating lens 11, the second collimating lens 12, and the third collimating lens 13, respectively, becoming parallel beams. They then pass through the second lens 14, the third lens 15, and the fourth lens 16, respectively, and continue through the reference object 17, forming the first spectral domain interferometric system probe beam 21, the second spectral domain interferometric system probe beam 22, and the third spectral domain interferometric system probe beam 23. These beams are focused onto the sample 5. The light reflected from the upper surface of the sample 5 and the lower surface of the reference object 17 returns to the fiber optic circulator 9 via the original optical path and finally enters the spectrometer 18. The spectrometer 18 collects the interference spectrum and transmits it to the computer 19 for demodulation, calculating the phase shift of the sample 5. The light emitted by the spectral domain interferometric system and the phase shift interferometric system illuminates the surface of the sample 5.

[0010] The phase-shifting interferometer probe light 24 is the position where the light emitted by the phase-shifting interferometer illuminates the surface of sample 5. The three spectral domain interferometer probe beams emitted by the spectral domain interferometer, namely the first spectral domain interferometer probe beam 21, the second spectral domain interferometer probe beam 22, and the third spectral domain interferometer probe beam 23, are located around the phase-shifting interferometer probe light 24, at three diagonal positions.

[0011] On the other hand, an optical phase-shifting interferometry detection method, based on the aforementioned optical phase-shifting interferometry detection device, specifically includes the following steps:

[0012] Step 1: Acquire interference images using a phase-shifting interferometer system:

[0013] Laser source 1 emits laser light, which is collimated into a parallel beam by collimating lens 2. After being reflected by beam splitter 3, it forms phase-shifting interference system probe light 24. The phase-shifting interference system probe light 24 passes through reference flat crystal 4 and illuminates the surface of sample 5. Moving platform 20 drives sample 5 to generate a small vibration. The sample light reflected by the lower surface of sample 5 and the reference light reflected by the upper surface of reference flat crystal 4 pass through beam splitter 3 and first lens 6, forming an interference image at area array camera 7. The area array camera 7 acquires the interference image and transmits it to computer 19 for processing and display.

[0014] Step 2: Acquire interference spectra using a spectral domain interferometry system:

[0015] The low-coherence light source 8 emits light, which enters the fiber optic circulator 9 and then the 1×3 coupler 10, where it is split into three beams. These beams pass through the first collimating lens 11, the second collimating lens 12, and the third collimating lens 13, respectively, and become parallel beams. They then pass through the second lens 14, the third lens 15, and the fourth lens 16, respectively, and continue to pass through the reference object 17, forming the first spectral domain interference system probe beam 21, the second spectral domain interference system probe beam 22, and the third spectral domain interference system probe beam 23. These three beams are focused onto the sample 5. The light reflected from the upper surface of the sample 5 and the lower surface of the reference object 17 returns to the fiber optic circulator 9 via the original optical path and finally enters the spectrometer 18. The spectrometer 18 collects the interference spectrum and transmits it to the computer 19 for demodulation, calculating the phase shift of the sample 5.

[0016] The area array camera 7 in step 1 and the spectrometer 18 in step 2 are synchronously triggered by the computer 19 to synchronously acquire the interference image of the phase-shifting interferometer system and the interference spectrum of the spectral domain interferometer system.

[0017] Step 3: Let S1, S2, and S3 represent the interference spectra formed by the reflections of three beams of light—the first spectral domain interferometer probe beam 21, the second spectral domain interferometer probe beam 22, and the third spectral domain interferometer probe beam 23—on the surfaces of sample 5 and reference object 17, acquired by the spectral domain interferometer system. S1, S2, and S3 are separable in the frequency domain. Combining the frequency and phase of the interference spectra, calculate the optical path differences L1(x1,y1,t), L2(x2,y2,t), and L3(x3,y3,t) of S1, S2, and S3, where (x1,y1), (x2,y2), and (x3,y3) represent the coordinates of the three light spots, and t represents the data acquired at time t. Using L1(x1,y1,t), L2(x2,y2,t), and L3(x3,y3,t) through plane fitting, obtain the phase shift P(x,y;t) of sample 5 relative to the reference flat crystal 4:

[0018] (1);

[0019] in, Let be the center wavenumber of the low-coherence light source 8, and (x, y) represent the sample surface coordinates. , , We obtain it from the following formula:

[0020] (2);

[0021] Step 4: The interferometric image acquired by the phase-shifting interferometer system is represented as follows:

[0022] (3);

[0023] in, Indicates t i The intensity of the interference image acquired at time t is at point (x, y). This represents the background light intensity at point (x, y). This represents the modulation index at point (x, y). This represents the phase of the sample surface at point (x, y), and the parameters are set accordingly. , , , and omitted The expressions are as follows:

[0024] (4);

[0025] but and The following formula is used to obtain M, where M represents the total number of phase-shifted interferometric images and M interferometric spectra acquired:

[0026] (5);

[0027] Calculate using Formula 5 and The sample surface profile is then obtained by the following formula, where unwrap() represents the dewrap function:

[0028] (6);

[0029] k represents the wavenumber of laser source 1.

[0030] The beneficial effects of adopting the above technical solution are as follows:

[0031] This invention provides an optical phase-shifting interferometry detection device and method, which has the following beneficial effects:

[0032] 1. This application uses a spectral domain interferometry system to detect the phase shift between the reference flat and the sample in real time. It does not require a quantitative phase shifter, can accurately obtain the real-time phase shift between the reference flat and the sample, does not require strict control of the phase shift of the phase shift interferometry system, has a fast acquisition speed, and is not affected by environmental interference.

[0033] 2. This application adopts the three-point detection method, which calculates the phase shift at each point between the reference flat and the sample through plane fitting, and is not affected by the tilt of the reference flat or the sample due to vibration.

[0034] 3. Since the real-time phase shift between the reference flat and the sample can be obtained, the effects of nonlinearity of CCD detectors, phase sign reversal problems, and phase shift non-uniformity caused by air disturbances can be avoided. Attached Figure Description

[0035] Figure 1 This is an overall diagram of an optical phase-shifting interferometry detection device according to an embodiment of the present invention;

[0036] Among them, 1-laser source, 2-collimating lens, 3-beam splitter, 4-reference flat crystal, 5-sample, 6-first lens, 7-area array camera, 8-low coherence light source, 9-fiber circulator, 10-1×3 coupler, 11-first collimator, 12-second collimator, 13-third collimator, 14-second lens, 15-third lens, 16-fourth lens, 17-reference object, 18-spectrometer, 19-computer, 20-mobile platform, 21-probe light of the first spectral domain interferometry system, 22-probe light of the second spectral domain interferometry system, 23-probe light of the third spectral domain interferometry system, 24-probe light of the phase-shifting interferometry system;

[0037] Figure 2 This is a schematic diagram of the light spot in an embodiment of the present invention. Detailed Implementation

[0038] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used for...

[0039] This invention is described but not intended to limit its scope.

[0040] On the one hand, an optical phase-shifting interferometry detection device, such as Figure 1 As shown, it consists of two parts: a phase-shifting interferometry system and a spectral domain interferometry system;

[0041] The phase-shifting interferometry system includes: a laser source 1, a collimating lens 2, a beam splitter 3, a reference flat crystal 4, a sample 5, a first lens 6, an area array camera 7, a computer 19, a mobile platform 20, and a phase-shifting interferometry system probe light 24.

[0042] like Figure 1 As shown, laser source 1 emits laser light, which is collimated into a parallel beam by collimating lens 2. The light is reflected by beam splitter 3 to form phase-shifting interference system probe light 24. The phase-shifting interference system probe light 24 passes through reference flat crystal 4 and illuminates the surface of sample 5. Moving platform 20 drives sample 5 to produce a small vertical displacement. The sample light reflected by the lower surface of sample 5 and the reference light reflected by the upper surface of reference flat crystal 4 pass through beam splitter 3 and first lens 6, forming an interference image at area array camera 7. The area array camera 7 acquires the interference image and transmits it to computer 19 for processing and display.

[0043] The spectral domain interferometry system includes: a low-coherence light source 8, an optical fiber circulator 9, a 1×3 coupler 10, a first collimator 11, a second collimator 12, a third collimator 13, a second lens 14, a third lens 15, a fourth lens 16, a reference object 17, a spectrometer 18, a first spectral domain interferometry system probe beam 21, a second spectral domain interferometry system probe beam 22, and a third spectral domain interferometry system probe beam 23;

[0044] like Figure 1 As shown, the low-coherence light source 8 emits light, which enters the fiber optic circulator 9 and then the 1×3 coupler 10, where it is split into three beams. These beams pass through the first collimator 11, the second collimator 12, and the third collimator 13, respectively, becoming parallel beams. They then pass through the second lens 14, the third lens 15, and the fourth lens 16, respectively, and continue through the reference object 17, forming the first spectral domain interferometric system probe beam 21, the second spectral domain interferometric system probe beam 22, and the third spectral domain interferometric system probe beam 23. These beams are focused onto the sample 5. The light reflected from the upper surface of the sample 5 and the lower surface of the reference object 17 returns to the fiber optic circulator 9 via the original optical path and finally enters the spectrometer 18. The spectrometer 18 collects the interference spectrum and transmits it to the computer 19 for demodulation, calculating the phase shift of the sample 5. The position of the light spot is shown in the figure. Figure 2 The light emitted by the spectral domain interferometry system and the phase-shifting interferometry system illuminates the surface of sample 5. The phase-shifting interferometry system probe beam 24 is located at the position where the light emitted by the phase-shifting interferometry system illuminates the surface of sample 5. The three beams of light emitted by the spectral domain interferometry system—the first spectral domain interferometry system probe beam 21, the second spectral domain interferometry system probe beam 22, and the third spectral domain interferometry system probe beam 23—are located around the phase-shifting interferometry system probe beam, at three diagonal positions. On the other hand, an optical phase-shifting interferometry detection method, based on the aforementioned optical phase-shifting interferometry detection device, specifically includes the following steps:

[0045] Step 1: Acquire interference images using a phase-shifting interferometer system:

[0046] like Figure 1 As shown, laser source 1 emits laser light, which is collimated into a parallel beam by collimating lens 2. After being reflected by beam splitter 3, it forms phase-shifting interferometer probe light 24. The phase-shifting interferometer probe light 24 passes through reference flat crystal 4 and illuminates the surface of sample 5. Moving platform 20 drives sample 5 to generate tiny vibrations. The sample light reflected by the lower surface of sample 5 and the reference light reflected by the upper surface of reference flat crystal 4 pass through beam splitter 3 and first lens 6, forming an interference image at area array camera 7. The area array camera 7 acquires the interference image and transmits it to computer 19 for processing and display.

[0047] Step 2: Acquire interference spectra using a spectral domain interferometry system:

[0048] like Figure 1 As shown, the low-coherence light source 8 emits light, which enters the fiber optic circulator 9 and then the 1×3 coupler 10, where it is split into three beams. The three beams pass through the first collimator 11, the second collimator 12, and the third collimator 13, respectively, and become parallel beams. They then pass through the second lens 14, the third lens 15, and the fourth lens 16, respectively, and continue to pass through the reference object 17, forming the first spectral domain interference system probe beam 21, the second spectral domain interference system probe beam 22, and the third spectral domain interference system probe beam 23. The first spectral domain interference system probe beam 21, the second spectral domain interference system probe beam 22, and the third spectral domain interference system probe beam 23 are focused on the sample 5. The light reflected from the upper surface of the sample 5 and the lower surface of the reference object 17 returns to the fiber optic circulator 9 through the original optical path and finally enters the spectrometer 18. The spectrometer 18 collects the interference spectrum and transmits it to the computer 19 for demodulation to calculate the phase shift of the sample 5.

[0049] The area array camera 7 in step 1 and the spectrometer 18 in step 2 are synchronously triggered by the computer 19 to synchronously acquire the interference image of the phase-shifting interferometer system and the interference spectrum of the spectral domain interferometer system.

[0050] Step 3: Let S1, S2, and S3 represent the interference spectra formed by the reflections of three beams of light—the first spectral domain interferometer probe beam 21, the second spectral domain interferometer probe beam 22, and the third spectral domain interferometer probe beam 23—on the surfaces of sample 5 and reference object 17, acquired by the spectral domain interferometer system. S1, S2, and S3 are separable in the frequency domain. Combining the frequency and phase of the interference spectra, calculate the optical path differences L1(x1,y1,t), L2(x2,y2,t), and L3(x3,y3,t) of S1, S2, and S3, where (x1,y1), (x2,y2), and (x3,y3) represent the coordinates of the three light spots, and t represents the data acquired at time t. By fitting L1(x1,y1,t), L2(x2,y2,t), and L3(x3,y3,t) to a plane, obtain the phase shift of sample 5 relative to the reference flat crystal 4. :

[0051] (1);

[0052] in, The center wavenumber of low-coherence light source 8 is... Indicates the coordinates of the sample surface. , , We obtain it from the following formula:

[0053] (2);

[0054] Step 4: The interferometric image acquired by the phase-shifting interferometer system is represented as follows:

[0055] (3);

[0056] in, Indicates t i The intensity of the interference image acquired at time t is at point (x, y). This represents the background light intensity at point (x, y). This represents the modulation index at point (x, y). This represents the phase of the sample surface at point (x, y), and the parameters are set accordingly. , , , and omitted The expressions are as follows:

[0057] (4);

[0058] but and The following formula is used to obtain M, where M represents the total number of phase-shifted interferometric images and M interferometric spectra acquired:

[0059] (5);

[0060] Calculate using Formula 5 and The sample surface profile is then obtained by the following formula, where unwrap() represents the dewrap function:

[0061] (6);

[0062] k represents the wavenumber of laser source 1;

[0063] This application can obtain interferograms of arbitrary amplitude, and the above algorithm can be used to detect three-dimensional contours.

[0064] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. An optical phase-shifting interferometry detection device, characterized in that, Including phase-shifting interferometry systems and spectral-domain interferometry systems; The phase-shifting interferometer system includes: a laser source (1), a collimating lens (2), a beam splitter (3), a reference flat (4), a sample (5), a first lens (6), an area array camera (7), a computer (19), a mobile platform (20), and a phase-shifting interferometer system probe light (24). The laser source (1) emits a laser beam, which is collimated into a parallel beam by the collimating lens (2). The beam is reflected by the beam splitter (3) to form the phase-shifting interference system probe light (24). The phase-shifting interference system probe light (24) shines on the surface of the sample (5) through the reference flat crystal (4). The moving platform (20) drives the sample (5) to produce a small vertical displacement. The sample light reflected by the lower surface of the sample (5) and the reference light reflected by the upper surface of the reference flat crystal (4) pass through the beam splitter (3) and the first lens (6) to form an interference image in the area array camera (7). The area array camera (7) collects the interference image and transmits it to the computer (19) for processing and display. The spectral domain interferometry system includes: a low-coherence light source (8), an optical fiber circulator (9), a 1×3 coupler (10), a first collimator (11), a second collimator (12), a third collimator (13), a second lens (14), a third lens (15), a fourth lens (16), a reference object (17), a spectrometer (18), a first spectral domain interferometry system probe light (21), a second spectral domain interferometry system probe light (22), and a third spectral domain interferometry system probe light (23); The low-coherence light source (8) emits light, which enters the fiber optic circulator (9) and then the 1×3 coupler (10), where it is split into three beams. These beams pass through the first collimator (11), the second collimator (12), and the third collimator (13), respectively, becoming parallel beams. They then pass through the second lens (14), the third lens (15), and the fourth lens (16), respectively, and continue to pass through the reference object (17), forming the first spectral domain interferometric system probe light (21), the second spectral domain interferometric system probe light (22), and the third spectral domain interferometric system probe light (23). The probe light (21), probe light (22), and probe light (23) of the first spectral domain interferometer system are focused on the sample (5). The light reflected from the upper surface of the sample (5) and the lower surface of the reference object (17) returns to the fiber optic circulator (9) through the original optical path and finally enters the spectrometer (18). The spectrometer (18) collects the interference spectrum and transmits it to the computer (19) for demodulation and calculates the phase shift of the sample (5). The light emitted by the spectral domain interferometer system and the phase shift interferometer system illuminates the surface of the sample (5).

2. The optical phase-shifting interferometry detection device according to claim 1, characterized in that, The phase-shifting interferometer probe light (24) is the position where the light emitted by the phase-shifting interferometer illuminates the surface of the sample (5). The three spectral domain interferometer probe beams emitted by the spectral domain interferometer, namely the first spectral domain interferometer probe light (21), the second spectral domain interferometer probe light (22), and the third spectral domain interferometer probe light (23), are located around the phase-shifting interferometer probe light (24) at three diagonal positions.

3. An optical phase-shifting interferometry detection method, implemented based on the optical phase-shifting interferometry detection device according to claim 1, characterized in that, Includes the following steps: Step 1: Acquire interference images using a phase-shifting interferometer system: The laser source (1) emits a laser beam, which is collimated into a parallel beam by the collimating lens (2). After being reflected by the beam splitter (3), it forms the phase-shifting interference system probe light (24). The phase-shifting interference system probe light (24) passes through the reference flat crystal (4) and then irradiates the surface of the sample (5). The moving platform (20) drives the sample (5) to generate a small vibration. The sample light reflected by the lower surface of the sample (5) and the reference light reflected by the upper surface of the reference flat crystal (4) pass through the beam splitter (3) and the first lens (6) to form an interference image in the area array camera (7). The interference image is acquired by the area array camera (7) and transmitted to the computer (19) for processing and display. Step 2: Acquire interference spectra using a spectral domain interferometry system: The low-coherence light source (8) emits light, which enters the fiber optic circulator (9) and then the 1×3 coupler (10), where it is split into three beams. These beams pass through the first collimator (11), the second collimator (12), and the third collimator (13) respectively, becoming parallel beams. They then pass through the second lens (14), the third lens (15), and the fourth lens (16), respectively, and continue to pass through the reference object (17), forming the first spectral domain interferometric system probe light (21), the second spectral domain interferometric system probe light (22), and the third spectral domain interferometric system probe light (23). The probe light (23), the three spectral domain interferometric system probe beams, namely the first spectral domain interferometric system probe light (21), the second spectral domain interferometric system probe light (22), and the third spectral domain interferometric system probe light (23), are focused on the sample (5). The light reflected from the upper surface of the sample (5) and the lower surface of the reference object (17) returns to the fiber optic circulator (9) through the original optical path and finally enters the spectrometer (18). The spectrometer (18) collects the interference spectrum and transmits it to the computer (19) for demodulation and calculates the phase shift of the sample (5). The area array camera (7) in step 1 and the spectrometer (18) in step 2 are synchronously triggered by the computer (19) to synchronously acquire the interference image of the phase-shifting interferometer system and the interference spectrum of the spectral domain interferometer system; Step 3: Let S1, S2, and S3 represent the interference spectra formed by the reflection of the three beams of light collected by the first spectral domain interference system probe light (21), the second spectral domain interference system probe light (22), and the third spectral domain interference system probe light (23) on the surfaces of the sample (5) and the reference object (17). S1, S2, and S3 are separable in the frequency domain. Combining the frequency and phase of the interference spectrum, calculate the optical path differences L1(x1,y1,t), L2(x2,y2, t), and L3(x3,y3, t) of S1, S2, and S3, where (x1,y1), (x2,y2), and (x3,y3) represent the coordinates of the three light spots, and t represents the data collected at time t. By fitting L1(x1,y1,t), L2(x2,y2,t), and L3(x3,y3,t) to the plane, obtain the phase shift P(x,y) of the sample (5) relative to the reference flat crystal (4). t）： （1）； in, Let (x, y) be the center wavenumber of the low-coherence light source (8), and (x, y) represent the coordinates of the sample surface. , , We obtain it from the following formula: （2）； Step 4: The interferometric image acquired by the phase-shifting interferometer system is represented as follows: (3)； in, Indicates t i The intensity of the interference image acquired at time t is at point (x, y). This represents the background light intensity at point (x, y). This represents the modulation index at point (x, y). This represents the phase of the sample surface at point (x, y), and the parameters are set accordingly. , , , and omitted The expressions are as follows: (4)； but and The following formula is used to obtain M, where M represents the total number of phase-shifted interferometric images and M interferometric spectra acquired: （5）； Calculate using formula (5) and The sample surface profile is then obtained by the following formula, where unwrap() represents the dewrap function: (6)； k represents the wavenumber of the laser source (1).

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