White light interference signal correction method and device based on frequency domain amplitude and phase iteration

Abstract

The invention relates to a white light interference signal correction method and device based on frequency domain amplitude and phase iteration, and relates to the technical field of optical measurement, and the method comprises the steps: collecting a white light interference signal, carrying out the Fourier transform, obtaining the frequency domain phase distribution, and carrying out the unwrapping; obtaining a linear phase through linear fitting, and subtracting the linear phase from a to-be-processed phase to extract a nonlinear phase; the sampling point corresponding to the nonlinear phase with the maximum absolute value is removed, linear interpolation is used for filling the point, and corrected frequency domain phase distribution is generated; gaussian distribution generated in the frequency domain serves as new amplitude distribution, the new amplitude distribution and the corrected phase form a new frequency domain interference signal, and inverse Fourier transform is carried out to obtain a corrected time domain signal; and filtering the corrected time domain white light interference signal by using a rectangular window, and determining whether to continue to correct according to an iteration standard. Through ideal amplitude replacement and phase iteration correction, the distortion influence of noise on the white light interference signal is solved, and the signal quality and the correction capability are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and more specifically to a method and apparatus for correcting white light interferometric signals based on frequency domain amplitude and phase iteration. Background Art

[0002] White light interferometry is a high-precision, high-speed, non-invasive measurement method widely used in the field of surface topography measurement. This method uses a broadband light source as the illumination source. After the beam passes through a beam splitter, one beam illuminates a reference mirror, and the other beam illuminates the object being measured. The two reflected beams form a white light interference signal. As the reference mirror is controlled to scan, the detector continuously collects the phase-modulated white light interference signal. The surface topography distribution of the object being measured is obtained by analyzing the white light interference signal.

[0003] During measurement, phase noise generated by environmental vibrations can distort the white light interference signal. Methods to eliminate this distortion mainly fall into two categories. The first category is hardware-based methods. Passive vibration removal methods include adding vibration isolation platforms or encasing the interferometer in a shell to passively isolate external noise. This method is effective to some extent, but significantly increases costs. Active methods involve adding a noise measurement system to detect and eliminate noise in the white light interference signal; this type of method is technically more challenging. The second category uses algorithms to correct the white light interference signal, such as using frequency domain phase distribution or eliminating bad points in the phase. This type of method significantly improves the analytical accuracy of the white light interference signal, but since it only performs signal processing once on the white light interference signal before outputting the measurement result, there is still room for further improvement in measurement accuracy. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method and apparatus for correcting white light interferometric signals based on frequency domain amplitude and phase iteration. This method eliminates the need for hardware modulation, saving costs and reducing system complexity. Simultaneously, it introduces amplitude correction to overcome amplitude distortion caused by phase errors, thereby improving the accuracy of the iterative algorithm. Furthermore, compared to other single-signal processing methods, multiple signal iterations further eliminate the influence of errors.

[0005] The specific plan is as follows:

[0006] On the one hand, white light interferometric signal correction methods based on frequency domain amplitude and phase iteration include:

[0007] S1, let the initial value of the iteration number n be 1, and the standard parameter for stopping iteration be M;

[0008] S2, acquire the time-domain white light interference signal collected by the white light interferometer;

[0009] S3, if n=1, perform a Fourier transform on the acquired time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed; otherwise, perform a Fourier transform on the filtered time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed.

[0010] S4. Perform linear fitting on the phase distribution to be processed to obtain the linear phase. Subtract the phase to be processed from the linear phase to obtain the nonlinear phase. Simultaneously, calculate the mean square error of the nonlinear phase. ;

[0011] S5. The point with the largest absolute value in the nonlinear phase is taken as the sampling point to be deleted. After deleting the sampling point, a new phase value is filled into the sampling point using a linear interpolation method to generate the corrected frequency domain phase distribution.

[0012] S6, the Gaussian distribution spectrum generated in the frequency domain is used as the amplitude of the frequency domain signal. Based on the amplitude of the frequency domain Gaussian distribution and the corrected frequency domain phase distribution, a new frequency domain interference signal is formed. The inverse Fourier transform of the new frequency domain interference signal is performed to obtain the corrected time-domain white light interference signal.

[0013] S7, if Then let n = n + 1, set the amplitude of the rectangular window, and use the rectangular window to filter the corrected time-domain white light interference signal, repeating S3-S6; if Then, the corrected time-domain white light interference signal is output; where, This is the mean squared error when n equals 1.

[0014] Furthermore, in S2, the process of the white light interferometer acquiring the time-domain white light interference signal is as follows:

[0015] The broadband light emitted from the white light source is expanded and parallelized by a lens before reaching the beam splitter. The first part of the light reaches the object under test and the second part reaches the reference mirror. The light reaching the object under test and the light reaching the reference mirror are reflected to the photodiode to form a white light interference signal. The piezoelectric actuator controls the reference mirror to perform scanning motion to achieve phase modulation of the white light interference signal. During the phase modulation process, the modulated white light interference signal is collected.

[0016] Furthermore, in S2, the acquired time-domain white light interference signal is represented as follows:

[0017] ;

[0018] in, The reference mirror surface position of the white light interferometer. The position on the surface of the object to be tested. The spectral distribution of the light source, It is the reciprocal of the wavelength. This is phase noise.

[0019] Furthermore, in S3, a Fourier transform is performed on the time-domain white light interference signal to obtain the frequency domain distribution, as shown in the following formula:

[0020] ;

[0021] in, This represents the amplitude in the frequency domain obtained after the Fourier transform of the white light interference signal; This represents the interference phase in the frequency domain caused by phase noise affecting the white light interference signal. for Frequency domain distribution; Represents the imaginary unit;

[0022] from Extracting the phase component from the given information yields the frequency domain phase distribution, as shown in the following formula:

[0023] ;

[0024] in, This represents the obtained frequency domain phase distribution.

[0025] Furthermore, in S3, the frequency domain phase distribution is all in Within the interval, the phase is truncated by inserting one or more complete cycles at the truncation points. , where k is an integer, restores the phase to a continuous state, unwraps the phase, and obtains the phase to be processed.

[0026] Furthermore, in S5, the use of linear interpolation to fill in a new phase value at the sampling point and generate a corrected frequency domain phase distribution specifically includes:

[0027] Let the coordinates of the points before and after the sampling point be (x0, y0) and (x1, y1), respectively. A line is obtained through these two points, as shown in the following formula:

[0028] ;

[0029] Sampling points to be deleted Substituting the x-coordinate into the formula yields the new phase value. The phase of the deleted sample points is replaced with new phase values ​​to generate a corrected frequency domain phase distribution.

[0030] Furthermore, in S6, the step of using the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal specifically includes:

[0031] Let the wavelength range of the white light source be... , ;in, where λ is the wavelength and f is the frequency domain. and The effective range of the frequency domain interference signal is defined by the two boundaries of the light source's spectral range. , and The sizes are respectively and The center position of the frequency domain signal is selected as A Gaussian spectrum is generated in the frequency domain. Let G(f) represent this Gaussian spectrum, and let f be the center position of the generated Gaussian spectrum. c Let the full width at half maximum (FWHM) of the Gaussian distribution spectrum be... f in the Gaussian distribution spectrum c and f s The corresponding value is represented as G(f) c ) and G(f s ),ensure The Gaussian spectrum that meets the conditions is used as the amplitude of the frequency domain signal.

[0032] Furthermore, in S7, the maximum value of the corrected time-domain white light interference signal is set to S. max (z), select a time-domain white light interference signal with an amplitude greater than S. max The part (z) / 10 corresponds to the range of , z s and z e Define a rectangular window for the boundary values ​​of this range, and set the window within [z... s , z e The value is 1 within the range of the rectangular window and 0 outside the range of the rectangular window. The rectangular window is used to filter the corrected white light interference signal.

[0033] On the other hand, a white light interferometric signal correction device based on frequency domain amplitude and phase iteration includes:

[0034] The iteration setting module is used to initialize the iteration count n to 1 and set the stopping iteration standard parameter to M.

[0035] The time-domain white light interferometer signal acquisition module is used to acquire the time-domain white light interferometer signal collected by the white light interferometer.

[0036] The phase acquisition module is used to perform a Fourier transform on the acquired time-domain white light interference signal if n=1, obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed; otherwise, it performs a Fourier transform on the filtered time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed.

[0037] The nonlinear phase acquisition module is used to perform linear fitting on the phase distribution to be processed to obtain a linear phase. The nonlinear phase is obtained by subtracting the phase to be processed from the linear phase, and the mean square error of the nonlinear phase is calculated simultaneously. ;

[0038] The frequency domain phase distribution correction module is used to obtain the point with the largest absolute value from the nonlinear phase as the sampling point to be deleted. After deleting the sampling point, a new phase value is filled into the sampling point using a linear interpolation method to generate the corrected frequency domain phase distribution.

[0039] The modified time-domain white light interference signal acquisition module is used to take the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal, and to form a new frequency domain interference signal based on the amplitude of the frequency domain Gaussian distribution and the modified frequency domain phase distribution. The inverse Fourier transform of the new frequency domain interference signal is then performed to obtain the modified time-domain white light interference signal.

[0040] The loop module is used to determine if... Then let n = n + 1, set the amplitude of the rectangular window, use the rectangular window to filter the corrected time-domain white light interference signal, and enter the next loop; if Then, the corrected time-domain white light interference signal is output; where, This is the mean squared error when n equals 1.

[0041] The present invention adopts the above technical solution and has the following beneficial effects:

[0042] (1) The present invention uses an ideal amplitude signal to replace the original amplitude that is distorted by noise, thereby eliminating the distortion of amplitude caused by noise as a whole. At the same time, it finds data points that are significantly affected by noise by phase. This method uses both amplitude and phase to reduce noise interference.

[0043] (2) The present invention corrects the white light interference signal multiple times through multiple iterations. Compared with the method of only performing signal processing once, the signal correction capability of this method is stronger. Attached Figure Description

[0044] Figure 1 This invention provides a method for correcting white light interferometric signals based on frequency domain amplitude and phase iteration.

[0045] Figure 2 This is a schematic diagram of a white light interferometer according to an embodiment of the present invention;

[0046] Figure 3(a) is a schematic diagram of the frequency domain amplitude and phase distribution of the original white light interference signal in an embodiment of the present invention;

[0047] Figure 3(b) is a schematic diagram of the absolute value distribution of the frequency domain nonlinear phase in an embodiment of the present invention;

[0048] Figure 4(a) is a schematic diagram of the amplitude distribution replaced by the Gaussian distribution in an embodiment of the present invention;

[0049] Figure 4(b) is a schematic diagram of the phase distribution after eliminating phase defects and interpolation according to an embodiment of the present invention;

[0050] Figure 5 This is a schematic diagram illustrating the range of the rectangular window selected based on the white light interference signal according to an embodiment of the present invention;

[0051] Figure 6 This is a structural block diagram of a white light interferometric signal correction device based on frequency domain amplitude and phase iteration according to an embodiment of the present invention. Detailed Implementation

[0052] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] like Figure 1 As shown, the present invention provides a white light interferometric signal correction method based on frequency domain amplitude and phase iteration, comprising:

[0054] S1, let the initial value of the iteration number n be 1, and the stopping iteration standard parameter be M.

[0055] Specifically, in this embodiment, the value of the stopping iteration standard parameter M is set to 10.

[0056] S2, acquire the time-domain white light interference signal collected by the white light interferometer.

[0057] Specifically, the process of acquiring time-domain white light interference signals using a white light interferometer is as follows:

[0058] The broadband light emitted from the white light source is expanded and parallelized by a lens before reaching the beam splitter. The first part of the light reaches the object under test and the second part reaches the reference mirror. The light reaching the object under test and the light reaching the reference mirror are reflected to the photodiode to form a white light interference signal. The piezoelectric actuator controls the reference mirror to perform scanning motion to achieve phase modulation of the white light interference signal. During the phase modulation process, the modulated white light interference signal is collected.

[0059] Specifically, the acquired time-domain white light interference signal is represented as follows:

[0060] ;

[0061] in, The reference mirror surface position of the white light interferometer. The position on the surface of the object to be tested. The spectral distribution of the light source, It is the reciprocal of the wavelength. This is phase noise.

[0062] Specifically, such as Figure 2 As shown in the figure, 1 is a white light source. The emitted broadband light is expanded and parallelized by lens 2 and then reaches beam splitter 3. Part of the light reaches the object under test 5, and the other part of the light reaches reference mirror 6. The reflected light from the object under test 5 and reference mirror 6 reaches photodiode 7. Piezoelectric actuator 4 controls the reference mirror to perform scanning motion.

[0063] Specifically, in this embodiment, the frequency domain interference signal to be corrected is represented by the frequency domain amplitude and phase distribution of the original white light interference signal as shown in Figure 3(a), and the absolute value distribution of the frequency domain nonlinear phase as shown in Figure 3(b).

[0064] S3, if n=1, perform a Fourier transform on the acquired time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed; otherwise, perform a Fourier transform on the filtered time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed.

[0065] Specifically, the frequency domain distribution is obtained by performing a Fourier transform on the acquired time-domain white light interference signal or on the filtered time-domain white light interference signal, as shown in the following formula:

[0066] ;

[0067] in, This represents the amplitude in the frequency domain obtained after the Fourier transform of the white light interference signal; This represents the interference phase in the frequency domain caused by phase noise affecting the white light interference signal. for Frequency domain distribution; Represents the imaginary unit;

[0068] from Extracting the phase component from the given information yields the frequency domain phase distribution, as shown in the following formula:

[0069] ;

[0070] in, This represents the obtained frequency domain phase distribution.

[0071] Specifically, the frequency domain phase distribution is all in Within the interval, the phase is truncated by inserting one or more complete cycles at the truncation points. , where k is an integer, restores the phase to a continuous state, unwraps the phase, and obtains the phase to be processed.

[0072] S4. Perform linear fitting on the phase distribution to be processed to obtain the linear phase. Subtract the phase to be processed from the linear phase to obtain the nonlinear phase. Simultaneously, calculate the mean square error of the nonlinear phase. ;

[0073] S5. The point with the largest absolute value in the nonlinear phase is taken as the sampling point to be deleted. After deleting the sampling point, a new phase value is filled into the sampling point using a linear interpolation method to generate the corrected frequency domain phase distribution.

[0074] Specifically, the method of using linear interpolation to fill in a new phase value at the sampling point and generate a corrected frequency domain phase distribution includes:

[0075] Let the coordinates of the points before and after the sampling point be (x0, y0) and (x1, y1), respectively. A line is obtained through these two points, as shown in the following formula:

[0076] ;

[0077] Sampling points to be deleted Substituting the x-coordinate into the formula yields the new phase value. The phase of the deleted sample points is replaced with new phase values ​​to generate a corrected frequency domain phase distribution.

[0078] S6 uses the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal. Based on the amplitude of the frequency domain Gaussian distribution and the corrected frequency domain phase distribution, a new frequency domain interference signal is formed. The new frequency domain interference signal is subjected to inverse Fourier transform to obtain the corrected time-domain white light interference signal.

[0079] Specifically, the method of using the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal includes:

[0080] Let the wavelength range of the white light source be... , ;in, where λ is the wavelength and f is the frequency domain. and The effective range of the frequency domain interference signal is defined by the two boundaries of the light source's spectral range. , and The sizes are respectively and The center position of the frequency domain signal is selected as A Gaussian spectrum is generated in the frequency domain, denoted by G(f). The center position of the generated Gaussian spectrum is also set to f. Let the full width at half maximum (FWHM) of the Gaussian distribution spectrum be... f in the Gaussian distribution spectrum c and f s The corresponding value is represented as G(f) c ) and G(f s ) ,ensure The Gaussian spectrum that meets the conditions is used as the amplitude of the frequency domain signal.

[0081] Specifically, in this embodiment, the modified interference signal schematic diagram is the amplitude distribution replaced by the Gaussian distribution shown in Figure 4(a), and the phase distribution after eliminating phase defects and interpolation shown in Figure 4(b).

[0082] S7, if Then let n = n + 1, set the amplitude of the rectangular window, and use the rectangular window to filter the corrected time-domain white light interference signal, repeating S3-S6; if Then, the corrected time-domain white light interference signal is output; where, This is the mean squared error when n equals 1.

[0083] Specifically, the maximum value of the corrected time-domain white light interference signal is set to S. max (z), select a time-domain white light interference signal with an amplitude greater than S. max The part (z) / 10 corresponds to the range [z]. s , z e ], z s and z e Define a rectangular window for the boundary values ​​of this range, and set the window within [z... s , z e The value is 1 within the range of the rectangular window and 0 outside the range of the rectangular window. The rectangular window is used to filter the corrected white light interference signal.

[0084] Specifically, such as Figure 5 As shown, this illustrates the range of the rectangular window selected based on the white light interference signal in an embodiment of the present invention.

[0085] like Figure 6 As shown, this embodiment also discloses a white light interferometric signal correction device based on frequency domain amplitude and phase iteration, including:

[0086] The iteration setting module 601 is used to initialize the iteration number n to 1 and set the stopping iteration standard parameter to M.

[0087] The time-domain white light interference signal acquisition module 602 is used to acquire the time-domain white light interference signal acquired by the white light interferometer;

[0088] The phase acquisition module 603 is used to perform a Fourier transform on the acquired time-domain white light interference signal if n=1, obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed; otherwise, it performs a Fourier transform on the filtered time-domain white light interference signal to obtain the frequency-domain phase distribution, and unwrap the frequency-domain phase distribution to obtain the phase to be processed.

[0089] The nonlinear phase acquisition module 604 is used to perform linear fitting on the phase distribution to be processed to obtain a linear phase, subtract the phase to be processed from the linear phase to obtain the nonlinear phase, and simultaneously calculate the mean square error of the nonlinear phase. ;

[0090] The frequency domain phase distribution correction module 605 is used to obtain the point with the largest absolute value from the nonlinear phase as the sampling point to be deleted. After deleting the sampling point, a new phase value is filled into the sampling point using a linear interpolation method to generate the corrected frequency domain phase distribution.

[0091] The modified time-domain white light interference signal acquisition module 606 is used to take the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal, and form a new frequency domain interference signal based on the amplitude of the frequency domain Gaussian distribution and the modified frequency domain phase distribution. The modified time-domain white light interference signal is obtained by performing an inverse Fourier transform on the new frequency domain interference signal.

[0092] Loop module 607 is used to determine if... Then let n = n + 1, set the amplitude of the rectangular window, use the rectangular window to filter the corrected time-domain white light interference signal, and enter the next loop; if Then, the corrected time-domain white light interference signal is output; where, This is the mean squared error when n equals 1.

[0093] The specific implementation of the white light interference signal correction device based on frequency domain amplitude and phase iteration is the same as the white light interference signal correction method based on frequency domain amplitude and phase iteration, and will not be described again in this embodiment.

[0094] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A white light interference signal correction method based on frequency domain amplitude and phase iteration, characterized in that: include: S1, set the initial value of the number of iterations n to 1, and the standard parameter for stopping iterations to M; S2, obtaining a time-domain white light interference signal collected by a white light interferometer; S3, if n=1, Fourier transform the collected time-domain white-light interference signal to obtain the frequency-domain phase distribution, unwrap the frequency-domain phase distribution, and obtain the phase to be processed; otherwise, Fourier transform the filtered time-domain white-light interference signal to obtain the frequency-domain phase distribution, unwrap the frequency-domain phase distribution, and obtain the phase to be processed; S4, linear fitting is performed on the phase distribution to be processed to obtain the linear phase, the phase to be processed and the linear phase are subtracted to obtain the nonlinear phase, and the mean square error of the nonlinear phase is calculated at the same time. ; S5, obtaining a point with the largest absolute value from the nonlinear phase as a sampling point to be deleted, and after deleting the sampling point, using a linear interpolation method to fill in a new phase value at the sampling point to generate a corrected frequency domain phase distribution; S6, using the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal, forming a new frequency domain interference signal based on the amplitude of the frequency domain Gaussian distribution and the corrected frequency domain phase distribution, and performing inverse Fourier transform on the new frequency domain interference signal to obtain a corrected time domain white light interference signal; S7, if , then let n=n+1, set the amplitude of the rectangular window, use the rectangular window to filter the corrected time-domain white light interference signal, and repeat S3-S6; if , then the corrected time-domain white light interference signal is output; where, is the mean square error when n is equal to 1.

2. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1 is characterized in that: In S2, the process of collecting the time-domain white light interference signal by the white light interferometer is as follows: The wide spectrum light emitted by the white light source is expanded and parallelized by a lens and reaches the spectrometer, obtaining the first part of the light reaching the object to be measured and the second part of the light reaching the reference mirror. The light reaching the object to be measured and the light reaching the reference mirror are reflected to the photodiode to form a white light interference signal. The piezoelectric actuator controls the reference mirror to perform a scanning motion to realize phase modulation of the white light interference signal, and the modulated white light interference signal is collected during the phase modulation process.

3. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1 is characterized in that: In S2, the collected time-domain white light interference signal is expressed as follows: ； in, is the surface position of the reference mirror of the white light interferometer, is the surface position of the object to be measured, is the spectral distribution of the light source, is the reciprocal of the wavelength, is the phase noise.

4. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1 is characterized in that: In S3, the time domain white light interference signal is Fourier transformed to obtain the frequency domain distribution, and the formula is as follows: ； in, Represents the amplitude in the frequency domain obtained after Fourier transform of the white light interference signal; It represents the interference phase in the frequency domain caused by the white light interference signal affected by phase noise. for The frequency domain distribution of represents an imaginary unit; from Extract the phase part and obtain the frequency domain phase distribution. The formula is as follows: ； in, represents the obtained frequency domain phase distribution.

5. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1, characterized in that: In S3, the frequency domain phase distribution is The phase is truncated within the interval by adding one or more complete cycles at the truncation point. , where k is an integer, the phase is restored to a continuous state, the phase is unwrapped, and the phase to be processed is obtained.

6. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1, characterized in that: In S5, the linear interpolation method is used to fill in the new phase value at the sampling point to generate a corrected frequency domain phase distribution, which specifically includes: Let the coordinates of the points before and after the sampling point be (x0, y0) and (x1, y1), and get a line through these two points. The formula is as follows: ； The sampling points to be deleted Substitute the horizontal coordinate of into the formula to get the new phase value , and use the new phase value to replace the phase of the deleted sampling point to generate a corrected frequency domain phase distribution.

7. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1, characterized in that: In S6, the step of using the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal specifically includes: Assume the wavelength range of the white light source is , ;in, is the wavelength, f is the frequency domain, and are the two boundaries of the light source spectrum range, and the effective range of the frequency domain interference signal is , and The sizes are and , select the center position of the frequency domain signal as , generate a Gaussian distribution spectrum in the frequency domain, and use G(f) to represent the Gaussian distribution spectrum. Let the center position of the generated Gaussian distribution spectrum also be , let the half-width of the Gaussian distribution spectrum be , the Gaussian distribution spectrum f c and f s The corresponding value is expressed as G(f c ) and G(f s ), ensuring that G(f c ) > 10×G(f s ), and the Gaussian spectrum that meets the conditions is taken as the amplitude of the frequency domain signal.

8. The white light interference signal correction method based on frequency domain amplitude and phase iteration according to claim 1, characterized in that: In S7, the maximum value of the modified time-domain white light interference signal is set to S max (z), select the time domain white light interference signal amplitude greater than S max (z) / 10, the corresponding range is [z s , z e ],z s and z e As the boundary value of the range, set a rectangular window so that the window is in [z s , z e ] is 1, and the value outside the rectangular window is 0, and the rectangular window is used to filter the corrected white light interference signal.

9. A white light interference signal correction device based on frequency domain amplitude and phase iteration, characterized in that: include: The iteration setting module is used to set the initial value of the number of iterations n to 1 and the standard parameter for stopping iterations to M; A time-domain white-light interference signal acquisition module is used to acquire the time-domain white-light interference signal acquired by the white-light interferometer; The phase acquisition module to be processed is used to perform Fourier transform on the collected time-domain white-light interference signal to obtain the frequency-domain phase distribution, unwrap the frequency-domain phase distribution, and obtain the phase to be processed if n=1; otherwise, perform Fourier transform on the filtered time-domain white-light interference signal to obtain the frequency-domain phase distribution, unwrap the frequency-domain phase distribution, and obtain the phase to be processed; The nonlinear phase acquisition module is used to perform linear fitting on the phase distribution to be processed to obtain the linear phase, subtract the phase to be processed from the linear phase to obtain the nonlinear phase, and calculate the mean square error of the nonlinear phase. ; A frequency domain phase distribution correction module is used to obtain the point with the largest absolute value from the nonlinear phase as the sampling point to be deleted, and after deleting the sampling point, a linear interpolation method is used to fill in the new phase value at the sampling point to generate a corrected frequency domain phase distribution; A modified time-domain white-light interference signal acquisition module is used to use the Gaussian distribution spectrum generated in the frequency domain as the amplitude of the frequency domain signal, form a new frequency-domain interference signal based on the amplitude of the frequency-domain Gaussian distribution and the modified frequency-domain phase distribution, and perform inverse Fourier transform on the new frequency-domain interference signal to obtain a modified time-domain white-light interference signal; Loop module, used to determine if , then let n=n+1, set the amplitude of the rectangular window, use the rectangular window to filter the corrected time-domain white light interference signal, and enter the next cycle; if , then the corrected time-domain white light interference signal is output; where, is the mean square error when n is equal to 1.

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