Two-plane absolute surface shape detection method and device based on multi-signal phase extraction

Abstract

The present application discloses a two-plane absolute surface shape detection method and device based on multi-signal phase extraction, which relates to the field of optical interference measurement technology. The rotational asymmetric error is obtained by using the wavefront phase distribution data of the initial position and the average value of the wavefront phase distribution data after multiple rotations; then the reference mirror is translated along the X-axis, and the wavefront phase distribution data after translation is measured, and the rotational symmetric error is obtained according to the wavefront phase distribution data after translation. The rotational symmetric error and the rotational asymmetric error are combined to obtain the surface shape error to be solved. The two-plane absolute surface shape detection method and device based on multi-signal phase extraction provided by the present application eliminate the error caused by the flipping of the mirror to be measured, improve the measurement accuracy, simplify the measurement steps, and improve the stability of surface shape detection.

Description

Technical Field

[0001] The present application relates to the technical field of optical interference measurement, and in particular to a two-plane absolute surface shape detection method and device based on multi-signal phase extraction. Background Art

[0002] Optical interferometry is a measurement method based on the wave principle of light to achieve nanometer and sub-nanometer precision. It is recognized as one of the most accurate and effective non-contact measurement methods for detecting optical components and optical system parameters. Modern optical interferometry is developed on the basis of traditional classical double-slit interference. It combines optical principles and digital image processing technology. In the prior art, the absolute detection methods of surface errors include rotational translation method and rotational shearing method.

[0003] The Rotate-Translate Method is a commonly used image registration method in the field of optical image processing and computer vision. Image registration refers to aligning the features in two or more images for subsequent comparison, analysis or fusion. The Rotate-Shear Method is also an image registration method, which is used to align two images and eliminate the rotation and shear transformations between them. Similar to the Rotate-Translate Method, the Rotate-Shear Method is also a commonly used technique in the field of image registration. However, the traditional Rotate-Translate Method cannot detect the high-frequency rotational symmetry terms and This results in low accuracy of surface error detection. Summary of the invention

[0004] To this end, the present application provides a two-plane absolute surface shape detection method and device based on multi-signal phase extraction to solve the problem of low accuracy of surface shape error detection methods in the prior art.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, a two-plane absolute surface detection method based on multi-signal phase extraction comprises:

[0007] Step 1: Obtain a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern using Fourier transform, and obtain wavefront phase distribution data at an initial position;

[0008] Step 2: respectively obtain the wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtain the wavefront phase distribution data after multiple rotations;

[0009] Step 3: Grouping the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations to obtain two groups of average wavefronts;

[0010] Step 4: Rotate the two sets of average wave surfaces 180° clockwise and counterclockwise respectively, then superimpose them and calculate the average wave surface;

[0011] Step 5: Make a differential equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error;

[0012] Step 6: Obtain the wavefront phase distribution data after the reference mirror is rotated to the initial position and translated along the X-axis, and obtain the wavefront phase distribution data after translation;

[0013] Step 7: Differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain the differential surface error;

[0014] Step 8: Perform Zernike fitting on the differential surface error to obtain the rotational symmetry error and item;

[0015] Step 9: Combine the rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

[0016] Preferably, in step 1, the superimposed interference fringe pattern is obtained using a Fizeau interferometer.

[0017] Preferably, in step 2, the reference mirror is rotated six times at equal angles.

[0018] Preferably, the reference mirror is rotated six times at equal angles to respective angles of 60°, 120°, 180°, 240°, 300° and 360°.

[0019] Preferably, step 3 specifically includes: sorting the wavefront phase distribution data at the initial position and multiple rotated wavefront phase distribution data according to the angle size, dividing the sorted wavefront phase distribution data into odd-numbered wavefronts and even-numbered wavefronts, and respectively calculating the average wavefronts of the odd-numbered items and the average wavefronts of the even-numbered items.

[0020] Preferably, a multi-signal aliasing phase extraction method is used when acquiring wavefront phase distribution data.

[0021] Preferably, the phase extraction method for multi-signal aliasing specifically includes: obtaining the light intensity value formed by the interference of reflected light from three surfaces of the test mirror and the reference mirror; performing Fourier transform on the light intensity value to obtain a spectrum; processing the spectrum through a filter window, and further performing inverse Fourier transform to obtain an analytical signal; unwrapping the analytical signal to obtain wavefront phase distribution data.

[0022] In a second aspect, a two-plane absolute surface detection device based on multi-signal phase extraction comprises:

[0023] An initial wavefront phase acquisition module is used to acquire a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern by Fourier transform, and acquire the wavefront phase distribution data at the initial position;

[0024] A rotation wavefront phase acquisition module is used to respectively acquire wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtain wavefront phase distribution data after multiple rotations;

[0025] A wavefront phase grouping module, used for grouping the wavefront phase distribution data at the initial position and the wavefront phase distribution data after a plurality of rotations to obtain two groups of average wavefronts;

[0026] The average wave surface calculation module is used to rotate the two groups of average wave surfaces 180 degrees clockwise and counterclockwise respectively, and then superimpose them and calculate the average wave surface;

[0027] A rotational asymmetric error calculation module is used to make a differential equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error;

[0028] The translation wavefront phase acquisition module is used to obtain the wavefront phase distribution data after the reference mirror is rotated to the initial position and translated along the X-axis, so as to obtain the wavefront phase distribution data after the translation;

[0029] A differential surface error calculation module is used to differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain a differential surface error;

[0030] The rotational symmetry error calculation module is used to perform Zernike fitting on the differential surface error to obtain the rotational symmetry error and item;

[0031] The absolute surface calculation module is used to calculate the rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

[0032] In a third aspect, a computer program product includes a computer program or instructions, which, when executed by a processor, implements the steps of a two-plane absolute surface detection method based on multi-signal phase extraction.

[0033] In a fourth aspect, a two-plane absolute surface shape detection system based on multi-signal phase extraction includes a mirror to be measured, a reference mirror, a first collimating lens, a half-reflecting half-mirror, a second collimating lens, a filter, a CCD camera, a computer, a third collimating lens, a reflector and a laser, wherein the reference mirror and the first collimating lens are fixedly connected via a mechanical displacement table, the computer, the CCD camera, the filter, the second collimating lens, the half-reflecting half-mirror, the first collimating lens, the reference mirror and the mirror to be measured are sequentially arranged from right to left along the optical path, the reflector is arranged at the laser output end of the laser, the third collimating lens is arranged between the reflector and the half-reflecting half-mirror, the half-reflecting half-mirror, the third collimating lens and the reflector are located on the same straight line, and the computer is used to execute the steps of a two-plane absolute surface shape detection method based on multi-signal phase extraction.

[0034] Compared with the prior art, this application has at least the following beneficial effects:

[0035] The present application provides a two-plane absolute surface shape detection method and device based on multi-signal phase extraction, using the wavefront phase distribution data of the initial position and the average value of the wavefront phase distribution data after multiple rotations to obtain the rotational asymmetric error; then the reference mirror is translated along the X-axis, and the wavefront phase distribution data after translation is measured, and the rotational symmetric error is obtained according to the translated wavefront phase distribution data, and the rotational symmetric error is combined with the rotational asymmetric error to obtain the solved surface shape error. The two-plane absolute surface shape detection method and device based on multi-signal phase extraction provided by the present application eliminates the error caused by the flipping of the mirror to be measured, improves the measurement accuracy, simplifies the measurement steps, and improves the stability of surface shape detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, those skilled in the art are capable of easily making conventional adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components) based on the technical concepts and exemplary drawings disclosed in the present application.

[0037] Figure 1 A flow chart of a two-plane absolute surface shape detection method based on multi-signal phase extraction provided in Example 1 of the present application;

[0038] Figure 2 A schematic diagram of the structure of a two-plane absolute surface shape detection method based on multi-signal phase extraction provided in Example 1 of the present application;

[0039] Figure 3 A schematic diagram of the structure of a two-plane absolute surface detection system based on multi-signal phase extraction provided in Example 4 of the present application.

[0040] Description of reference numerals:

[0041] 1. Mirror to be tested; 2. Reference mirror; 3. First collimating lens; 4. Half-reflecting half-mirror; 5. Second collimating lens; 6. Filter; 7. CCD camera; 8. Computer; 9. Third collimating lens; 10. Reflecting mirror; 11. Laser; 12. Mechanical translation stage. DETAILED DESCRIPTION

[0042] The present application is further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0043] In the description of this application: unless otherwise specified, "plurality" means two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0044] The terms such as "upper", "lower", "left", "right", "middle", etc. cited in this application are usually used to indicate the general relative position relationship for the purpose of intuitive understanding by referring to the drawings, and are not absolute limitations on the position relationship in the actual product.

[0045] Embodiment 1

[0046] See also Figure 1 and Figure 2 This embodiment provides a two-plane absolute surface shape detection method based on multi-signal phase extraction, which uses a multi-signal aliasing phase extraction method and a detection technology for rotational symmetric error and rotational asymmetric error signals to achieve surface shape detection on three planes. The method includes:

[0047] S1: Obtain a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern by Fourier transform, and obtain wavefront phase distribution data at an initial position;

[0048] Specifically, a Fizeau interferometer is used to collect the superimposed interference fringe pattern. At the initial position, the multi-signal frequency information of the superimposed interference fringe pattern is separated by Fourier transform, and the wavefront phase distribution data at the initial position is measured.

[0049] The wavefront phase distribution data is obtained by using a multi-signal aliasing phase extraction method. The principle of this method is to change the wavelength and use an interferometer to detect the interference light intensity at the initial position. Specifically, the following steps are included:

[0050] S101: Obtain the light intensity value formed by the interference of reflected light from the three surfaces of the test mirror and the reference mirror ;

[0051] S102: Perform Fourier transform on the light intensity value to obtain a spectrum ;

[0052] S103: Process the spectrum through a filter window and continue to perform inverse Fourier transform to obtain an analytical signal;

[0053] S104: Unpacking the analytical signal to obtain wavefront phase distribution data.

[0054] The phase extraction method of multi-signal aliasing uses a Fizeau interferometer to collect superimposed interference fringe patterns, and then transforms the coordinate values ​​into the frequency domain pixel by pixel through fast Fourier transform, takes the frequencies of the first few peaks, and then converts them into phase angles through Fourier transform, thereby obtaining the initial phases of multiple surfaces.

[0055] The wavefront phase distribution data obtained in this step is the wavefront phase distribution data at the initial position, which is recorded as:

[0056] .

[0057] S2: respectively obtaining wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtaining wavefront phase distribution data after multiple rotations;

[0058] Specifically, in this step, the reference mirror is rotated 6 times at equal angles (i.e., the reference mirror is rotated 60° in sequence), and after each rotation, the multi-signal aliasing phase extraction method is used to measure data to obtain 6 wavefront phase distribution data. The wavefront phase distribution data obtained in this step has a small error, which is convenient for subsequent data processing.

[0059] The reference mirror rotates six times at equal angles: 60°, 120°, 180°, 240°, 300° and 360°. The wavefront phase distribution data measured each time are recorded as:

[0060] ;

[0061] ;

[0062] ;

[0063] ;

[0064] ;

[0065] .

[0066] It should be noted that in this step, the three-dimensional morphological features of the two surfaces can be obtained simultaneously by separating the superimposed interference fringes of multiple surfaces obtained by a single measurement through an algorithm.

[0067] S3: grouping the wavefront phase distribution data at the initial position and the wavefront phase distribution data after a plurality of rotations to obtain two groups of average wavefronts;

[0068] Specifically, this step sorts the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations according to the angle size, divides the sorted wavefront phase distribution data into odd-numbered wavefronts and even-numbered wavefronts, and calculates the average wavefronts of the odd-numbered items and the average wavefronts of the even-numbered items, respectively.

[0069] More specifically, this step sorts the 7 wavefront phase distribution data obtained in the first two steps from small to large according to the angle size, sums the wavefronts of the 1st, 3rd, 5th, and 7th wavefront phase distribution data after sorting, and then averages the wavefronts to obtain the average wavefront of odd items; the wavefronts of the 2nd, 4th, and 6th wavefront phase distribution data after sorting are also summed, and then averaged to obtain the average wavefront of even items.

[0070] In other words, this step will:

[0071] ,

[0072] ,

[0073] ,

[0074] It is divided into odd-number wave surfaces, and the average wave surface of the odd-number items is calculated, which can be expressed by the formula:

[0075] ;

[0076] Then add:

[0077] ,

[0078] ,

[0079] It is divided into even-number wave surfaces, and the average wave surface of even-number items is calculated, which can be expressed by the formula:

[0080] ,

[0081] in, represents the rotational symmetric surface shape of the measured mirror, Indicates the rotationally asymmetric surface shape of the mirror being measured.

[0082] S4: rotate the two sets of average wave surfaces 180° clockwise and counterclockwise respectively, then superimpose them and calculate the average wave surface;

[0083] Specifically, in this step, the average wave surface of the odd-numbered items obtained in step 3 is rotated 180° clockwise to obtain , the average wave surface of the even-numbered items is rotated 180° counterclockwise to obtain , and then the two sets of data are superimposed to obtain , and then take the average to get the average wave surface .

[0084] S5: Make a difference equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error;

[0085] Specifically, this step will and Do the difference equation, expressed as:

[0086] ,

[0087] The rotational asymmetric error of the surface error is obtained according to the differential equation (none item).

[0088] S6: Obtain wavefront phase distribution data after the reference mirror is rotated to an initial position and translated along the X-axis, and obtain wavefront phase distribution data after translation;

[0089] Specifically, in this step, the reference mirror is translated along the X-axis, and the interference light intensity is detected at the initial position using an interferometer, and the light intensity formed by the interference of the reflected light from the three surfaces is obtained as , and then perform Fourier transform to obtain the spectrum , and then the obtained spectrum is processed through the filter window, followed by inverse Fourier transform to obtain the analytical signal, and finally the unwrapping process is performed to obtain the shifted wavefront phase distribution data, which is recorded as .

[0090] S7: Differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain a differential surface error;

[0091] Specifically, in this step, the wavefront phase distribution data after translation is differentiated from the wavefront phase distribution data at the initial position to obtain the differential surface error, which is expressed as follows:

[0092] .

[0093] S8: Perform Zernike fitting on the differential surface error to obtain the rotational symmetric error and item;

[0094] Specifically, in this step, the differential surface error is subjected to Zernike fitting to obtain the rotational symmetric error of the surface error: and item.

[0095] S9: The rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

[0096] Specifically, this step converts the rotational asymmetric error of the surface error into (none Item), rotational symmetry error of surface error and The wavefronts are summed up to obtain the complete surface shapes of the measured mirror and the reference mirror. Based on the absolute surface shapes of the front surface of the measured mirror and the reference mirror, the rear surface of the measured mirror can be obtained, thus completing the absolute surface shape measurement of the three surfaces.

[0097] The present embodiment provides a two-plane absolute surface shape detection method based on multi-signal phase extraction, which obtains multiple sets of phase information by rotating and translating a reference mirror, and completes the phase extraction of multiple signals by separating the frequency signals, thereby obtaining the surface shape information of the reference mirror and the front surface of the mirror to be measured, the reference mirror and the rear surface of the mirror to be measured, and the front and rear surfaces of the mirror to be measured. Subsequently, a wavefront reconstruction algorithm based on the least squares fitting principle is used to solve a group of differential equations, thereby achieving high-resolution signal extraction of rotationally symmetric surface shape errors and remaining rotationally asymmetric surface shape errors, and finally achieving absolute surface shape detection of the front surface of the mirror to be measured, the rear surface of the mirror to be measured, and the reference mirror.

[0098] The present embodiment provides a two-plane absolute surface shape detection method based on multi-signal phase extraction, which simultaneously uses a multi-signal aliasing phase extraction method and a rotation translation method based on Zernike polynomial fitting, thereby eliminating the error caused by the flipping of the mirror to be measured, improving the measurement accuracy, simplifying the measurement steps, and improving the stability of surface shape detection. Secondly, the surface shape error is divided into two odd and even terms in the present embodiment, so that the accuracy of surface shape error calculation is higher. The method uses a multi-signal aliasing phase extraction method to obtain the surface shape information of two superimposed surfaces, and obtains the rotationally symmetric part and the rotationally asymmetric part with the improved two-plane detection method based on Zernike polynomial fitting, and obtains the absolute surface shape information of each surface.

[0099] Embodiment 2

[0100] This embodiment provides a two-plane absolute surface detection device based on multi-signal phase extraction, comprising:

[0101] An initial wavefront phase acquisition module is used to acquire a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern by Fourier transform, and acquire the wavefront phase distribution data at the initial position;

[0102] A rotation wavefront phase acquisition module is used to respectively acquire wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtain wavefront phase distribution data after multiple rotations;

[0103] A wavefront phase grouping module, used for grouping the wavefront phase distribution data at the initial position and the wavefront phase distribution data after a plurality of rotations to obtain two groups of average wavefronts;

[0104] The average wave surface calculation module is used to rotate the two groups of average wave surfaces 180 degrees clockwise and counterclockwise respectively, and then superimpose them and calculate the average wave surface;

[0105] A rotational asymmetric error calculation module is used to make a differential equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error;

[0106] The translation wavefront phase acquisition module is used to obtain the wavefront phase distribution data after the reference mirror is rotated to the initial position and translated along the X-axis, so as to obtain the wavefront phase distribution data after the translation;

[0107] A differential surface error calculation module is used to differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain a differential surface error;

[0108] The rotational symmetry error calculation module is used to perform Zernike fitting on the differential surface error to obtain the rotational symmetry error and item;

[0109] The absolute surface calculation module is used to calculate the rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

[0110] For the specific implementation content of each module in a two-plane absolute surface detection device based on multi-signal phase extraction, please refer to the above definition of a two-plane absolute surface detection method based on multi-signal phase extraction, which will not be repeated here.

[0111] Embodiment 3

[0112] This embodiment provides a computer program product, including a computer program or instructions, which, when executed by a processor, implements the steps of a two-plane absolute surface detection method based on multi-signal phase extraction.

[0113] Embodiment 4

[0114] See also Figure 3 The present embodiment provides a two-plane absolute surface shape detection system based on multi-signal phase extraction, comprising a mirror to be measured 1, a reference mirror 2, a first collimating lens 3, a semi-reflective semi-mirror 4, a second collimating lens 5, a filter 6, a CCD camera 7, a computer 8, a third collimating lens 9, a reflector 10 and a laser 11, wherein the reference mirror 2 and the first collimating lens 3 are fixedly connected via a mechanical displacement stage 12, the computer 8, the CCD camera 7, the filter 6, the second collimating lens 5, the semi-reflective semi-mirror 4, the first collimating lens 3, the reference mirror 2 and the mirror to be measured 1 are sequentially arranged from right to left along the optical path, the reflector 10 is arranged at the laser emission end of the laser, the third collimating lens 9 is arranged between the reflector 10 and the semi-reflective semi-mirror 4, the semi-reflective semi-mirror 4, the third collimating lens 9 and the reflector 10 are located on the same straight line, and the computer 8 is used to execute the steps of a two-plane absolute surface shape detection method based on multi-signal phase extraction provided in the first embodiment.

[0115] The present embodiment provides a two-plane absolute surface detection system based on multi-signal phase extraction. With the help of wavelength phase shifting, a quasi-software phase shift measurement method, the mechanical stress error caused by hardware phase shift measurement can be avoided, thereby achieving fast and high-precision optical detection of large-aperture optical flat panel components.

[0116] The technical features of the above embodiments may be arbitrarily combined (as long as there is no contradiction in the combination of these technical features). To make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A two-plane absolute surface detection method based on multi-signal phase extraction, characterized in that: include: Step 1: Obtain a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern using Fourier transform, and obtain wavefront phase distribution data at an initial position; Step 2: respectively obtain the wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtain the wavefront phase distribution data after multiple rotations; Step 3: grouping the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations to obtain two groups of average wavefronts; specifically: sorting the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations according to the angle size, dividing the sorted wavefront phase distribution data into odd-numbered wavefronts and even-numbered wavefronts, and calculating the odd-numbered average wavefronts and the even-numbered average wavefronts respectively; Step 4: Rotate the two sets of average wave surfaces 180° clockwise and counterclockwise respectively, then superimpose them and calculate the average wave surface; Step 5: Make a differential equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error; Step 6: Obtain the wavefront phase distribution data after the reference mirror is rotated to the initial position and translated along the X-axis, and obtain the wavefront phase distribution data after translation; Step 7: Differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain the differential surface error; Step 8: Perform Zernike fitting on the differential surface error to obtain the rotational symmetry error and item; Step 9: Combine the rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

2. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 1 is characterized in that: In step 1, the superimposed interference fringe pattern is obtained using a Fizeau interferometer.

3. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 1 is characterized in that: In step 2, the reference mirror is rotated six times at equal angles.

4. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 3 is characterized in that: The reference mirror is rotated six times at equal angles, and the angles of rotation are: 60°, 120°, 180°, 240°, 300° and 360° respectively.

5. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 1 is characterized in that: Step 3 specifically includes: sorting the wavefront phase distribution data at the initial position and multiple rotated wavefront phase distribution data according to the angle size, dividing the sorted wavefront phase distribution data into odd-numbered wavefronts and even-numbered wavefronts, and calculating the average wavefronts of the odd-numbered items and the average wavefronts of the even-numbered items respectively.

6. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 1 is characterized in that: The phase extraction method of multiple signal aliasing is used to obtain wavefront phase distribution data.

7. The two-plane absolute surface detection method based on multi-signal phase extraction according to claim 6 is characterized in that: The phase extraction method for multi-signal aliasing specifically includes: obtaining the light intensity value formed by the interference of reflected light from three surfaces of the test mirror and the reference mirror; performing Fourier transform on the light intensity value to obtain a spectrum; processing the spectrum through a filter window and further performing inverse Fourier transform to obtain an analytical signal; and unpacking the analytical signal to obtain wavefront phase distribution data.

8. A two-plane absolute surface detection device based on multi-signal phase extraction, characterized in that: include: An initial wavefront phase acquisition module is used to acquire a superimposed interference fringe pattern, separate the multi-signal frequency information in the superimposed interference fringe pattern by Fourier transform, and acquire the wavefront phase distribution data at the initial position; A rotation wavefront phase acquisition module is used to respectively acquire wavefront phase distribution data after the reference mirror is rotated multiple times at equal angles, and obtain wavefront phase distribution data after multiple rotations; The wavefront phase grouping module is used to group the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations to obtain two groups of average wavefronts; specifically, the wavefront phase distribution data at the initial position and the wavefront phase distribution data after multiple rotations are sorted according to the angle size, the sorted wavefront phase distribution data are divided into odd-numbered wavefronts and even-numbered wavefronts, and the odd-numbered average wavefronts and the even-numbered average wavefronts are calculated respectively; The average wave surface calculation module is used to rotate the two groups of average wave surfaces 180 degrees clockwise and counterclockwise respectively, and then superimpose them and calculate the average wave surface; A rotational asymmetric error calculation module is used to make a differential equation between the average wavefront and the wavefront phase distribution data at the initial position to obtain the rotational asymmetric error of the surface error; The translation wavefront phase acquisition module is used to obtain the wavefront phase distribution data after the reference mirror is rotated to the initial position and translated along the X-axis, so as to obtain the wavefront phase distribution data after the translation; A differential surface error calculation module is used to differentiate the wavefront phase distribution data after translation from the wavefront phase distribution data at the initial position to obtain a differential surface error; The rotational symmetry error calculation module is used to perform Zernike fitting on the differential surface error to obtain the rotational symmetry error and item; The absolute surface calculation module is used to calculate the rotational asymmetric error of the surface error, the rotational symmetric error of the surface error and The wavefront is summed up by the items to obtain the complete surface shapes of the measured mirror and the reference mirror.

9. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method steps of any one of claims 1 to 7 are implemented.

10. A two-plane absolute surface detection system based on multi-signal phase extraction, characterized in that: The invention comprises a mirror to be measured, a reference mirror, a first collimating lens, a half-reflecting half-mirror, a second collimating lens, a filter, a CCD camera, a computer, a third collimating lens, a reflector and a laser, wherein the reference mirror and the first collimating lens are fixedly connected via a mechanical displacement stage, the computer, the CCD camera, the filter, the second collimating lens, the half-reflecting half-mirror, the first collimating lens, the reference mirror and the mirror to be measured are sequentially arranged from right to left along the optical path, the reflector is arranged at the laser emitting end of the laser, the third collimating lens is arranged between the reflector and the half-reflecting half-mirror, the half-reflecting half-mirror, the third collimating lens and the reflector are located on the same straight line, and the computer is used to execute the method steps described in any one of claims 1 to 7.

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