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

Abstract

The present invention relates to a white light interference signal correction method and device based on frequency domain amplitude and phase iteration, and to the field of optical measurement technology. The method includes: collecting white light interference signals and performing Fourier transform, obtaining frequency domain phase distribution and unpacking; obtaining linear phase by linear fitting, and extracting nonlinear phase by subtracting it from the phase to be processed; removing the sampling point corresponding to the nonlinear phase with the largest absolute value, filling the point with linear interpolation, and generating a corrected frequency domain phase distribution; using the Gaussian distribution generated in the frequency domain as a new amplitude distribution, and forming a new frequency domain interference signal with the corrected phase, and then performing inverse Fourier transform to obtain a corrected time domain signal; using a rectangular window to filter the corrected time domain white light interference signal, and deciding whether to continue correction according to an iteration standard. The present invention solves the distortion effect of noise on white light interference signals through ideal amplitude substitution and phase iterative correction, and significantly improves signal quality and correction capability.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement technology, and in particular to a white light interference signal correction method and device based on frequency domain amplitude and phase iteration. Background Art

[0002] White light interferometry is a high-precision, high-speed, non-invasive measurement method that is widely used in the field of surface topography measurement. This method uses a wide-spectrum light source as the illumination light source. After the light beam passes through the spectroscope, one beam is irradiated to the reference mirror and the other beam is irradiated to the object being measured. The two reflected lights 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, and the surface topography distribution of the object being measured is obtained by analyzing the white light interference signal.

[0003] During the measurement process, the phase noise generated by environmental vibration will cause the white light interference signal to be distorted. There are two main ways to eliminate this type of distortion. The first type is a hardware-based method, in which the passive way to remove vibration is to add a vibration isolation platform, put a shell on the interferometer, etc. to passively isolate the external noise. This method has a certain effect, but the cost is significantly increased; the active method is to add a noise measurement system to detect and eliminate the noise of the white light interference signal. This type of method has a high technical difficulty. The second type is to use an algorithm to correct the white light interference signal. For example, using frequency domain phase distribution or eliminating bad points in the phase. This method significantly improves the resolution accuracy of the white light interference signal, but this method only processes the white light interference signal once and outputs the measurement result. There is still room for further improvement in measurement accuracy. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a white light interference signal correction method and device based on frequency domain amplitude and phase iteration, which does not require hardware modulation, saves costs, reduces the complexity of the system, and introduces amplitude correction to overcome the amplitude distortion introduced by phase error and improve the accuracy of the iterative algorithm. In addition, multiple signal iterative processing further eliminates the influence of errors compared to other single signal processing.

[0005] The specific plan is as follows:

[0006] On the one hand, a white light interference signal correction method based on frequency domain amplitude and phase iteration includes:

[0007] S1, set the initial value of the number of iterations n to 1, and the standard parameter for stopping iterations to M;

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

[0009] 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;

[0010] 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. ;

[0011] 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;

[0012] 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;

[0013] 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.

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

[0015] 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.

[0016] Further, in S2, the collected time-domain white light interference signal is expressed as follows:

[0017] ;

[0018] 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.

[0019] Furthermore, in S3, the time domain white light interference signal is subjected to Fourier transform to obtain the frequency domain distribution, and the formula is as follows:

[0020] ;

[0021] 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;

[0022] from Extract the phase part and obtain the frequency domain phase distribution. The formula is as follows:

[0023] ;

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

[0025] Further, 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.

[0026] Further, in S5, the use of a linear interpolation method to fill in a new phase value at the sampling point to 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), and get a line through these two points. The formula is as follows:

[0028] ;

[0029] 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.

[0030] Further, in S6, the Gaussian distribution spectrum generated in the frequency domain is used as the amplitude of the frequency domain signal, specifically including:

[0031] Assume that 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 f c , 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 ),ensure , and the Gaussian spectrum that meets the conditions is used as the amplitude of the frequency domain signal.

[0032] Further, 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 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.

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

[0034] 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;

[0035] 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;

[0036] 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;

[0037] 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. ;

[0038] 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;

[0039] 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;

[0040] 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.

[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 the amplitude caused by noise as a whole. At the same time, the data points that are obviously affected by noise are found through the phase. This method uses amplitude and phase together to reduce the interference of noise.

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

[0044] Figure 1 A white light interference signal correction method based on frequency domain amplitude and phase iteration according to an embodiment of the present invention;

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

[0046] FIG3 (a) is a schematic diagram of the frequency domain amplitude and phase distribution of the original white light interference signal according to an embodiment of the present invention;

[0047] FIG3( b ) is a schematic diagram of absolute value distribution of nonlinear phase in the frequency domain according to an embodiment of the present invention;

[0048] FIG4 (a) is a schematic diagram of an amplitude distribution replaced by a Gaussian distribution according to an embodiment of the present invention;

[0049] FIG4( b ) is a schematic diagram of phase distribution after eliminating phase bad points and interpolation according to an embodiment of the present invention;

[0050] Figure 5 A schematic diagram of a range for selecting a rectangular window according to a white light interference signal according to an embodiment of the present invention;

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

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

[0053] like Figure 1 As shown, the white light interference signal correction method based on frequency domain amplitude and phase iteration of the present invention comprises:

[0054] S1, set the initial value of the number of iterations n to 1, and the standard parameter for stopping iteration to M.

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

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

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

[0058] 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.

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

[0060] ;

[0061] 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.

[0062] Specifically, Figure 2 As shown in the figure, 1 is a white light source, the emitted wide spectrum light is expanded and parallelized by lens 2 and reaches spectrometer 3, part of the light reaches the object to be measured 5, and the other part of the light reaches the reference mirror 6, the reflected light from the object to be measured 5 and the reference mirror 6 reaches the photodiode 7, and the piezoelectric actuator 4 controls the reference mirror to perform scanning motion.

[0063] Specifically, the frequency domain interference signal to be corrected in this embodiment is represented by the frequency domain amplitude and phase distribution of the original white light interference signal as shown in FIG3( a ), and the absolute value distribution of the frequency domain nonlinear phase as shown in FIG3( b ).

[0064] S3, if n=1, 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; 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.

[0065] Specifically, the collected time-domain white-light interference signal is Fourier transformed or the filtered time-domain white-light interference signal is Fourier transformed to obtain the frequency domain distribution, and the formula is as follows:

[0066] ;

[0067] 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;

[0068] from Extract the phase part and obtain the frequency domain phase distribution. The formula is as follows:

[0069] ;

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

[0071] Specifically, 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.

[0072] 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. ;

[0073] 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;

[0074] Specifically, the linear interpolation method is used to fill in the new phase value at the sampling point to generate the corrected frequency domain phase distribution, which specifically includes:

[0075] 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:

[0076] ;

[0077] 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.

[0078] S6, taking 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, performing inverse Fourier transform on the new frequency domain interference signal, and obtaining a 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 specifically includes:

[0080] Assume that 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 ) ,ensure , and the Gaussian spectrum that meets the conditions is used as the amplitude of the frequency domain signal.

[0081] Specifically, in this embodiment, the schematic diagram of the corrected interference signal is the amplitude distribution replaced by the Gaussian distribution shown in FIG4(a), and the phase distribution after eliminating phase bad points and interpolation shown in FIG4(b).

[0082] 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.

[0083] Specifically, 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.

[0084] Specifically, Figure 5 As shown, the range of the rectangular window is selected according to the white light interference signal in the embodiment of the present invention.

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

[0086] Iteration setting module 601, used to set the initial value of the iteration number n to 1 and the stop 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 to be processed is used to, if n=1, 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; 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;

[0089] The nonlinear phase acquisition module 604 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. ;

[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, and after deleting the sampling point, use the linear interpolation method to fill in the new phase value at the sampling point to generate a corrected frequency domain phase distribution;

[0091] The modified time-domain white-light interference signal acquisition module 606 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;

[0092] Loop module 607, 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.

[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 repeated in this embodiment.

[0094] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present 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 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 frequency-domain phase distribution, unwrap the frequency-domain phase distribution, and obtain the phase to be processed; 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, and calculate the mean square error σ of the nonlinear phase n ; 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 σ n >σ1 / M, 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 σ n ≤σ1 / M, the corrected time-domain white-light interference signal is output; where σ1 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 then 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 reference mirror is 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: Where z is the surface position of the reference mirror of the white light interferometer, z o is the surface position of the object to be measured, I(f) is the spectral distribution of the light source, f 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: Among them, I F (f) represents the amplitude in the frequency domain obtained after Fourier transform of the white light interference signal; v(f) represents the interference phase in the frequency domain caused by the white light interference signal affected by phase noise, and F(f) is the frequency domain distribution of S(z); j represents the imaginary unit; Extract the phase part from F(f) to 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 in the interval [-π, π], and the phase is truncated. By adding one or more complete cycles 2kπ 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 horizontal coordinate of the deleted sampling point x is substituted into the formula to obtain a new phase value y, and the new phase value is used 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 that the wavelength range of the white light source is [λ s ,λ e ], f = 1 / λ; where λ is the wavelength, f is the reciprocal of the wavelength, λ s and λ e are the two boundaries of the light source spectrum range, and the effective range of the frequency domain interference signal is [f e , f s ],f e and f s The sizes of them are 1 / λ e and 1 / λ s , select the center position of the frequency domain signal as f c =(f s +f e ) / 2, a Gaussian distribution spectrum is generated in the frequency domain, and G(f) is used to represent the Gaussian distribution spectrum. The center position of the generated Gaussian distribution spectrum is also set to f c , let the half-width of the Gaussian distribution spectrum be (f s -f e ) / 2, the Gaussian distribution spectrum f c and f s The corresponding value is expressed as G(f c ) and G(f s ), ensuring 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 for, if n=1, performing Fourier transform on the collected time-domain white-light interference signal to obtain the frequency-domain phase distribution, unpacking the frequency-domain phase distribution, and obtaining the phase to be processed; otherwise, performing Fourier transform on the filtered time-domain white-light interference signal to obtain the frequency-domain phase distribution, unpacking the frequency-domain phase distribution, and obtaining 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 σ of the nonlinear phase. n ; 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; The loop module is used to determine if σ n >σ1 / M, 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 σ n ≤σ1 / M, the corrected time-domain white-light interference signal is output; where σ1 is the mean square error when n is equal to 1.

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