Built-in rotation and translation absolute inspection interference device and surface shape measurement method

Abstract

The invention discloses a built-in rotation and translation absolute inspection interference device and a surface shape measurement method. The device comprises a short-coherence polarized light source module, a large-aperture Fizeau interference system, a built-in wave surface regulation and control module and an image acquisition module. According to the invention, rotation and translation regulation and control of an interference wave surface are realized through the built-in rotation and translation device, and a rotation and translation regulation and control mode of an external large-aperture element in traditional absolute inspection interferometry is converted into a built-in regulation and control mode. According to the invention, an external adjusting mechanism of the measuring device is simplified, and the measuring precision and the measuring efficiency of absolute inspection are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of optical interferometry testing technology, and in particular to a built-in rotation and translation absolute inspection interferometer and a surface shape measurement method. Background Technology

[0002] With the increasingly widespread application of large-aperture planar optical elements, the need for interferometric absolute testing of these elements is becoming more urgent. Currently, the main absolute testing schemes for large-aperture planar optical elements include two-plane and three-plane schemes, with testing operations primarily involving rotation, flipping, and translation. Since these operations involve large-aperture planar optical elements, large rotation and translation adjustment mechanisms are required for the interferometer, increasing its complexity and reducing measurement reliability. Furthermore, the clamping process for large-aperture optical elements is complex, making it difficult to maintain consistent stress-relieving support under various rotational states, leading to increased measurement errors. Although a long stress-relief process can be implemented after rotation, inherent surface shape changes caused by gravity remain, further reducing measurement accuracy. Additionally, the long stress-relief period after each rotation makes the measurement process very time-consuming, typically requiring tens of hours to complete a single measurement, resulting in low efficiency. Therefore, to address the problems of stress deformation caused by rotation of large-aperture optical elements and low measurement efficiency, an in-situ absolute testing device and method are needed that achieves high efficiency and high precision measurement without altering the orientation of the large-aperture optical element. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a built-in rotation and translation absolute inspection interferometer and a surface shape measurement method based on the device. The main idea is to construct a wavefront control module inside the interferometer, and use the interference principle of short polarization coherence to separate the reference wavefront and the test wavefront. Through this module, the test wavefront is rotated and translated relative to the reference wavefront, thereby achieving high-efficiency and high-precision absolute inspection without changing the state of the external large-aperture optical components.

[0004] The technical solution to achieve the purpose of this invention is as follows: On the one hand, a built-in rotation and translation absolute verification interferometer is provided, the absolute verification device including a short coherence polarization light source module, a large aperture Fizeau interferometer system, a built-in wavefront adjustment module and an image acquisition module;

[0005] The short coherent polarization light source module is used to adjust the output orthogonally polarized short coherent light;

[0006] The large-aperture Fizeau interferometer system is used to perform interferometric measurements;

[0007] The built-in wavefront control module is used to rotate and translate the wavefront, thereby achieving equivalent operations of rotating and translating large-aperture optical elements.

[0008] The image acquisition module is used to image and acquire phase-shifted interferograms of large-aperture optical elements.

[0009] Furthermore, the short-coherence polarization light source module includes a short-coherence laser, a first half-wave plate, a first polarization beam splitter, a first quarter-wave plate, a second quarter-wave plate, a first plane mirror, a second plane mirror, a second half-wave plate, a first fiber optic interface, and a polarization-maintaining fiber arranged along the optical axis. The polarized light emitted from the short-coherence laser is transmitted through the first half-wave plate, reflected by the first polarization beam splitter as S-beam, and transmitted as P-beam. The P-beam is transmitted through the first quarter-wave plate, reflected by the first plane mirror, and transmitted through the first quarter-wave plate to become S-beam, and then reflected by the first polarization beam splitter. The S-beam is transmitted through the second quarter-wave plate, reflected by the second plane mirror, and transmitted through the second quarter-wave plate to become P-beam, and then transmitted through the first polarization beam splitter. The P-beam and S-beam finally enter the large-aperture Fizeau interferometer system through the second half-wave plate, the first fiber optic interface, and the polarization-maintaining fiber. An equipathic virtual surface of the first plane mirror is formed in the optical path where the second plane mirror is located.

[0010] Furthermore, the large-aperture Fizeau interferometer system includes a second fiber optic interface, a beam splitter, a collimating objective lens, a reference lens, a test lens, and a first aperture stop. The polarized light emitted from the short-coherence polarization source module is emitted as a spherical wave through the second fiber optic interface, then transmitted sequentially through the beam splitter, the collimating objective lens, and the reference lens before being reflected by the test lens. It is then transmitted again through the collimating objective lens and reflected by the beam splitter, converging at the center of the first aperture stop. The second fiber optic interface and the first aperture stop are both located at the object-side focal point of the collimating objective lens and are conjugates. The distance between the reference lens and the test lens is equal to the distance between the second plane mirror and the equipathic virtual surface.

[0011] Furthermore, the built-in wavefront control module includes a first lens group, a second polarizing beam splitter, a first beam rotator, a first reflecting mirror, a third polarizing beam splitter, a second beam rotator, a second reflecting mirror, a linear polarizer, and a second lens group. Multiple linearly polarized beams converged at the first aperture become parallel beams after passing through the first lens group, and then are reflected by the second polarizing beam splitter (S-beams) and transmitted through the second polarizing beam splitter (P-beams). The S-beams, after passing through the first beam rotator, are reflected sequentially by the first reflecting mirror, reflected by the third polarizing beam splitter, transmitted through the linear polarizer, and finally converged by the second lens group. The P-beams, reflected by the second reflecting mirror, pass through the second beam rotator, are transmitted sequentially by the third polarizing beam splitter, transmitted through the linear polarizer, and finally converged by the second lens group.

[0012] Furthermore, the built-in wavefront manipulation module separates the incident orthogonally linearly polarized light with equal optical path lengths, thereby achieving the separation of the reference wavefront and the test wavefront.

[0013] Furthermore, the built-in wavefront control module can realize the function of rotating and translating the test wavefront; facing the light propagation direction, the first beam rotator (19) is rotated counterclockwise around the optical axis. The angle allows the test wavefront to rotate counterclockwise by a factor of 2 around the optical axis in the direction directly opposite to the light propagation direction. Angle; the direction of light propagation reflected from the first reflecting mirror (20), and the distance the first reflecting mirror (20) is translated in the direction perpendicular to the optical axis. This allows the test wavefront to be translated a distance in the same direction perpendicular to the optical axis. .

[0014] Furthermore, the image acquisition module includes a second aperture, an imaging lens group, and an area array detector; the linearly polarized light converged at the center of the second aperture by the second lens group is imaged onto the target surface of the area array detector by the imaging lens group to obtain a set of phase-shifted interferograms.

[0015] Furthermore, the first aperture and the second aperture are located at the front focal plane of the first lens group and the rear focal plane of the second lens group, respectively. The rear focal plane of the first lens group and the front focal plane of the second lens group coincide, and the first aperture and the second aperture form a conjugate relationship. The centers of the first beam rotator and the second beam rotator are located at the coincident plane of the rear focal plane of the first lens group and the front focal plane of the second lens group. The second aperture is located at the front focal plane of the imaging lens group.

[0016] On the other hand, a surface shape measurement method based on the above-described device is provided, the method comprising:

[0017] Step 1: The short coherent polarization light source module emits a pair of light sources with optical path difference. Orthogonally linearly polarized light, each of which generates two optical path differences when passed through a large-aperture Fizeau interferometer system. The reference collimated light and the test collimated light, and the four linearly polarized lights are controlled by the built-in wavefront adjustment module and then emitted into the image acquisition module.

[0018] Step 2: Rotate and adjust the first half-wave plate so that the two beams of light split by the first polarizing beam splitter are similar in intensity; rotate and adjust the first quarter-wave plate so that the intensity of the light emitted from the short-coherent laser after passing through the first plane mirror and the first polarizing beam splitter reaches its maximum value; rotate and adjust the second quarter-wave plate so that the intensity of the light emitted from the laser after passing through the second plane mirror and the first polarizing beam splitter reaches its maximum value; rotate and adjust the second half-wave plate so that the intensity of the two beams split by the second polarizing beam splitter is similar.

[0019] Step 3: Move the first and second plane mirrors parallel to the optical axis to change their relative distance to the first polarizing beam splitter and perform optical path matching so that the contrast of the interference pattern fringes collected on the area array detector reaches the user-defined optimal value. At this point, the reference wavefront and the test wavefront are separated. Fine-tune the linear polarizer until the fringe contrast reaches the user-defined optimal value. Adjust the attitude of the reference mirror and the test mirror and set the exposure time of the area array detector so that the interference pattern fringes are adjusted to the user-defined optimal state.

[0020] Step 4: Translate the first plane mirror along the optical axis to perform phase shifting, and simultaneously acquire the interferogram;

[0021] Step 5: Use the phase resolution algorithm to solve the phase-shifted interferogram acquired by the area array detector to obtain the i-th wavefront shape of the relative interference. , , This represents the total number of wavefront shapes.

[0022] Step 6: Extract the surface shape obtained in Step 5 using the stress birefringence error correction method. The polarization error included ;

[0023] Step 7: Calculate the surface shape result obtained in Step 5. Subtract the polarization error obtained in step 6 This allows us to obtain a wavefront shape without polarization error. ;

[0024] Step 8: Perform the procedure according to the corresponding absolute test method. Second wavefront rotation operation and Second wavefront translation operation, in which... All are non-negative integers, and satisfy the following conditions: , The total number of wavefront shapes; repeat steps 4 to 7 for a total of Second-rate;

[0025] Step 9, for the information obtained in step 8 wavefront shape Using the corresponding absolute verification algorithm, the absolute surface shape data is obtained. subscript For the face shape number, , This represents the total number of mirror surfaces participating in the test.

[0026] Furthermore, the specific process of the stress birefringence error correction method in step 6 is as follows:

[0027] Step 6-1: After completing steps 1 to 5, obtain the first wavefront shape measurement result, denoted as... ;

[0028] Step 6-2: Based on the device used in Step 6-1, rotate and adjust the second half-wave plate to reduce the light intensity received by the area array detector until the light intensity returns to the level in Step 6-1. Then stop. After completing steps 4 and 5, obtain the second wavefront shape measurement result, denoted as... ;

[0029] Step 6-3, process the wavefront results obtained in step 6-1. And the wavefront results obtained in step 6-2 By subtracting the values, the polarization error can be obtained. .

[0030] Compared with the prior art, the significant advantages of this invention are:

[0031] (1) The device can maintain the static characteristics of the interference cavity structure, which not only eliminates the complex large-scale rotation and translation mechanism, but also reduces the difficulty of stress relief clamping of the large mirror, and completely solves the problem of stress deformation and self-weight deformation caused by the rotation of the large mirror, effectively improving the accuracy of absolute inspection.

[0032] (2) Since the measurement process no longer requires a long stress release process, the measurement time can be shortened from tens of hours to within minutes, effectively improving the efficiency of absolute inspection.

[0033] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of an absolute verification interference device with built-in rotation and translation in one embodiment.

[0035] Figure 2 This is a schematic diagram of the wavefront rotation angle in one embodiment. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0039] In one embodiment, combined Figure 1 An absolute verification interferometer with built-in rotation and translation is provided. The absolute verification device includes a short coherence polarization light source module, a large aperture Fizeau interferometer system, a built-in wavefront adjustment module, and an image acquisition module.

[0040] The short coherent polarization light source module is used to adjust the output orthogonally polarized short coherent light;

[0041] The large-aperture Fizeau interferometer system is used to perform interferometric measurements;

[0042] The built-in wavefront control module is used to rotate and translate the wavefront, thereby achieving equivalent operations of rotating and translating large-aperture optical elements.

[0043] The image acquisition module is used to image and acquire phase-shifted interferograms of large-aperture optical elements.

[0044] Further, in one embodiment, the short coherent polarization light source module includes a short coherent laser 1, a first half-wave plate 2, a first polarizing beam splitter 3, a first quarter-wave plate 4, a second quarter-wave plate 6, a first plane mirror 5, a second plane mirror 7, a second half-wave plate 8, a first fiber optic interface 9, and a polarization-maintaining fiber 10 arranged along the optical axis; the polarized light emitted from the short coherent laser 1 is transmitted through the first half-wave plate 2, reflected by the first polarizing beam splitter 3 as S-beam, and transmitted as P-beam; the P-beam is transmitted through the first quarter-wave plate 4, reflected by the first plane mirror 5, and transmitted through the first quarter-wave plate 4 to become S-beam, and then reflected by the first polarizing beam splitter 3; the S-beam is transmitted through the second quarter-wave plate 6, reflected by the second plane mirror 7, and transmitted through the second quarter-wave plate 6 to become P-beam, and then transmitted through the first polarizing beam splitter 3; the P-beam and S-beam finally enter the large-aperture Fizeau interferometer system through the second half-wave plate 8, the first fiber optic interface 9, and the polarization-maintaining fiber 10; an equipathic virtual surface 30 of the first plane mirror 5 is formed in the optical path where the second plane mirror 7 is located.

[0045] Further, in one embodiment, the large-aperture Fizeau interferometer system includes a second fiber optic interface 11, a beam splitter 12, a collimating objective lens 13, a reference lens 14, a test lens 15, and a first aperture 16; the polarized light emitted from the short coherence polarization source module is emitted as a spherical wave through the second fiber optic interface 11, then transmitted sequentially through the beam splitter 12, the collimating objective lens 13, and the reference lens 14 before being reflected by the test lens 15, and then transmitted again through the collimating objective lens 13 and reflected by the beam splitter 12, converging at the center of the first aperture 16; the second fiber optic interface 11 and the first aperture 16 are both located at the object-side focal point of the collimating objective lens 13, and are conjugates; the distance between the reference lens 14 and the test lens 15 is equal to the distance between the second plane mirror 7 and the equipathic virtual surface 30.

[0046] Further, in one embodiment, the built-in wavefront adjustment module 29 includes a first lens group 17, a second polarizing beam splitter 18, a first beam rotator 19, a first reflecting mirror 20, a third polarizing beam splitter 23, a second beam rotator 21, a second reflecting mirror 22, a linear polarizer 24, and a second lens group 25. The four linearly polarized beams converged at the first aperture 16 become parallel beams after passing through the first lens group 17, and then are reflected by the second polarizing beam splitter 18, while the P beams are transmitted. The S beams pass through the first beam rotator 19, are reflected by the first reflecting mirror 20, reflected by the third polarizing beam splitter 23, transmitted by the linear polarizer 24, and finally converged by the second lens group 25. The P beams are reflected by the second reflecting mirror 22, pass through the second beam rotator 21, are transmitted by the third polarizing beam splitter 23, transmitted by the linear polarizer 24, and finally converged by the second lens group 25.

[0047] Preferably, in some embodiments, the built-in wavefront control module 29 separates the reference wavefront and the test wavefront by separating the incident orthogonally linearly polarized light with equal optical path length.

[0048] Preferably, in some embodiments, the built-in wavefront manipulation module 29 can realize the function of rotating and translating the test wavefront; facing the light propagation direction, the first beam rotator 19 is rotated counterclockwise around the optical axis. The angle allows the test wavefront to rotate counterclockwise by a factor of 2 around the optical axis in the direction directly opposite to the light propagation direction. Angle; the distance by which the first reflecting mirror 20 is translated in the direction perpendicular to the optical axis, directly facing the direction of light propagation of the reflected light. This allows the test wavefront to be translated a distance in the same direction perpendicular to the optical axis. .

[0049] Here, the function of the second beam rotator 21 is to ensure the consistency of the influence of the built-in wavefront control module 29 on the reference wavefront and the test wavefront, so that the reference wavefront and the test wavefront still maintain equal optical path lengths after being stripped.

[0050] Furthermore, in one embodiment, the image acquisition module includes a second aperture 26, an imaging lens group 27, and an area array detector 28; the linearly polarized light that is converged at the center of the second aperture 26 by the second lens group 25 is imaged onto the target surface of the area array detector 28 by the imaging lens group 27 to obtain a set of phase-shifted interferograms.

[0051] Preferably, in some embodiments, the first aperture 16 and the second aperture 26 are located at the front focal plane of the first lens group 17 and the rear focal plane of the second lens group 25, respectively. The rear focal plane of the first lens group 17 and the front focal plane of the second lens group 25 coincide, so that the first lens group 17 and the second lens group 25 constitute a 4F system, and the first aperture 16 and the second aperture 26 are conjugate, ensuring that the light spots of the first aperture 16 and the second aperture 26 are completely equivalent.

[0052] Preferably, in some embodiments, the centers of the first beam rotator 19 and the second beam rotator 21 are located at the coincidence surface of the rear focal plane of the first lens group 17 and the front focal plane of the second lens group 25, ensuring that the volume of the first beam rotator 19 and the second beam rotator 21 is minimized and the structure is compact; the second aperture 26 is located at the front focal plane of the imaging lens group 27.

[0053] In one embodiment, a surface shape measurement method based on the above-described device is provided, the method comprising:

[0054] Step 1: The short coherent polarization light source module emits a pair of light sources with optical path difference. Orthogonally linearly polarized light, each of which generates two optical path differences when passed through a large-aperture Fizeau interferometer system. The reference collimated light and the test collimated light, and the four linearly polarized lights are controlled by the built-in wavefront adjustment module and then emitted into the image acquisition module.

[0055] Step 2: Rotate and adjust the first half-wave plate 2 so that the two beams of light split by the first polarizing beam splitter 3 of the output light from the short coherence laser 1 have similar intensities; rotate and adjust the first quarter-wave plate 4 so that the output light intensity reaches its maximum value after passing through the first plane mirror 5 and the first polarizing beam splitter 3 in sequence; rotate and adjust the second quarter-wave plate 6 so that the output light intensity reaches its maximum value after passing through the second plane mirror 7 and the first polarizing beam splitter 3 in sequence; rotate and adjust the second half-wave plate 8 so that the two beams of light split by the second polarizing beam splitter 18 have similar intensities.

[0056] Step 3: Move the first plane mirror 5 and the second plane mirror 7 parallel to the optical axis to change the relative distance between them and the first polarizing beam splitter 3, and perform optical path matching so that the contrast of the interference pattern fringes collected on the area array detector 28 reaches the user-defined optimal value. At this time, the separation of the reference wavefront and the test wavefront is achieved. Fine-tune the linear polarizer 24 until the fringe contrast reaches the user-defined optimal value. Adjust the attitude of the reference mirror 14 and the test mirror 15, and set the exposure time of the area array detector 28 so that the interference pattern fringes are adjusted to the user-defined optimal state.

[0057] Step 4: Translate the first plane mirror 5 along the optical axis to perform phase shifting, and simultaneously acquire the interferogram;

[0058] Step 5: Use the phase resolution algorithm to solve the phase-shifted interferogram acquired by the array detector 28 to obtain the i-th wavefront shape of the relative interference. , , This represents the total number of wavefront shapes.

[0059] Step 6: Extract the surface shape obtained in Step 5 using the stress birefringence error correction method. The polarization error included ;

[0060] Step 7: Calculate the surface shape result obtained in Step 5. Subtract the polarization error obtained in step 6 This allows us to obtain a wavefront shape without polarization error. ;

[0061] Step 8: Perform the procedure according to the corresponding absolute test method. Second wavefront rotation operation and Second wavefront translation operation, in which... All are non-negative integers, and satisfy the following conditions: , The total number of wavefront shapes; repeat steps 4 to 7 for a total of Second-rate;

[0062] Step 9, for the information obtained in step 8 wavefront shape Using the corresponding absolute verification algorithm, the absolute surface shape data is obtained. subscript For the face shape number, , This represents the total number of mirror surfaces participating in the test.

[0063] Preferably, in some embodiments, the specific process of the stress birefringence error correction method in step 6 is as follows:

[0064] Step 6-1: After completing steps 1 to 5, obtain the first wavefront shape measurement result, denoted as... ;

[0065] Step 6-2: Based on the device used in Step 6-1, rotate and adjust the second half-wave plate 8 to reduce the light intensity received by the area array detector 28 until the light intensity returns to the level in Step 6-1. Then stop. After completing steps 4 and 5, obtain the second wavefront shape measurement result, denoted as... ;

[0066] Step 6-3, process the wavefront results obtained in step 6-1. And the wavefront results obtained in step 6-2 By subtracting the values, the polarization error can be obtained. .

[0067] Preferably, in some embodiments, the wavefront rotation in step 8 is implemented as follows:

[0068] Step 8-1: Determine the rotation of the first beam rotator 19 based on the state of the short coherent polarization light source module;

[0069] Step 8-2, as follows Figure 2 As shown, facing the direction of light propagation, the beam wavefront passing through the first beam rotator 19 is in a Cartesian coordinate system. This indicates that the test wavefront is in a Cartesian coordinate system. This indicates that, based on the rotation angle of the first beam rotator 19 and wavefront rotation angle The correspondence between them, that is Determine the wavefront rotation The required rotation angle of the first beam rotator 19 Rotate the first beam rotator 19.

[0070] Preferably, in some embodiments, the wavefront translation in step 8 is implemented as follows:

[0071] Step 8-3: Based on the state of the short coherent polarization light source module, determine the translation of the first reflecting mirror 20;

[0072] Step 8-4, based on the translation distance of the first reflecting mirror 20 along the direction perpendicular to the optical axis of the reflected light. and wavefront translation distance The correspondence between them, that is Determine the wavefront translation distance Required mirror translation distance ; Move the first reflecting mirror 20.

[0073] In summary, the absolute verification device and method of the present invention have the advantages of high efficiency and high precision. Their core advantage lies in completing the rotation and translation of the wavefront through a built-in device, without altering the state of the external large-aperture optical element, effectively avoiding the adverse effects of external disturbances and the device's own stress. Furthermore, the inherent self-weight stress of the large-aperture optical element can be effectively eliminated by employing appropriate error correction techniques.

[0074] This invention not only simplifies the external adjustment mechanism of the measuring device, but also effectively improves the measurement accuracy and efficiency of absolute inspection.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A built-in rotational-translational absolute verification interference device, characterized in that, The absolute testing device includes a short coherence polarization light source module, a large aperture Fizeau interferometer system, a built-in wavefront adjustment module, and an image acquisition module. The short coherent polarization light source module is used to adjust the output orthogonally polarized short coherent light; The large-aperture Fizeau interferometer system is used to perform interferometric measurements; The built-in wavefront control module is used to rotate and translate the wavefront, thereby achieving equivalent operations of rotating and translating large-aperture optical elements. The image acquisition module is used to image and acquire phase-shifted interferograms of large-aperture optical elements.

2. The built-in rotational translation absolute verification interference device according to claim 1, characterized in that, The short coherent polarization light source module includes a short coherent laser (1) arranged along the optical axis, a first half-wave plate (2), a first polarization beam splitter (3), a first quarter-wave plate (4), a second quarter-wave plate (6), a first plane mirror (5), a second plane mirror (7), a second half-wave plate (8), a first fiber optic interface (9), and a polarization-maintaining fiber (10). The polarized light emitted from the short coherent laser (1) is transmitted through the first half-wave plate (2), reflected by the first polarization beam splitter (3) as S-beam, and transmitted as P-beam. The P-beam is transmitted sequentially through the first quarter-wave plate (4), the first half-wave plate (5), the second half-wave plate (7), the second half-wave plate (8), the first fiber optic interface (9), and the first polarization-maintaining fiber (10). A plane mirror (5) reflects and a first quarter-wave plate (4) transmits the light into S-beams, which are then reflected by a first polarizing beam splitter (3). The S-beams are then transmitted through a second quarter-wave plate (6), reflected by a second plane mirror (7), and transmitted through a second quarter-wave plate (6) to become P-beams, which are then transmitted through a first polarizing beam splitter (3). The P-beams and S-beams finally enter the large-aperture Fizeau interference system through a second half-wave plate (8), a first fiber optic interface (9), and a polarization-maintaining fiber (10). In the optical path where the second plane mirror (7) is located, an equipathic virtual surface (30) of the first plane mirror (5) is formed.

3. The built-in rotational translation absolute verification interference device according to claim 2, characterized in that, The large-aperture Fizeau interferometer system includes a second fiber optic interface (11), a beam splitter (12), a collimating objective (13), a reference mirror (14), a test mirror (15), and a first aperture (16). The polarized light emitted from the short coherence polarization source module is emitted as a spherical wave through the second fiber optic interface (11), and then transmitted sequentially through the beam splitter (12), the collimating objective (13), and the reference mirror (14), and reflected by the test mirror (15). It is then transmitted again through the collimating objective (13) and reflected by the beam splitter (12), converging at the center of the first aperture (16). The second fiber optic interface (11) and the first aperture (16) are both located at the object-side focal point of the collimating objective (13), and they are conjugate. The distance between the reference mirror (14) and the test mirror (15) is equal to the distance between the second plane mirror (7) and the equipathic virtual surface (30).

4. The built-in rotational translation absolute inspection interference device according to claim 3, characterized in that, The built-in wavefront adjustment module (29) includes a first lens group (17), a second polarizing beam splitter (18), a first beam rotator (19), a first reflector (20), a third polarizing beam splitter (23), a second beam rotator (21), a second reflector (22), a linear polarizer (24), and a second lens group (25). The multiple linearly polarized beams converged at the first aperture (16) become parallel beams after passing through the first lens group (17), and then reflect S-beams and transmit P-beams through the second polarizing beam splitter (18). After passing through the first beam rotator (19), the S-beams are reflected by the first reflector (20), reflected by the third polarizing beam splitter (23), and transmitted by the linear polarizer (24), and finally converged by the second lens group (25). The P-beams are reflected by the second reflector (22), and after passing through the second beam rotator (21), they are transmitted by the third polarizing beam splitter (23) and transmitted by the linear polarizer (24), and finally converged by the second lens group (25).

5. The built-in rotational translation absolute verification interference device according to claim 4, characterized in that, The built-in wavefront control module (29) separates the incident orthogonally linearly polarized light with equal optical path length, thereby separating the reference wavefront and the test wavefront.

6. The built-in rotational translation absolute inspection interference device according to claim 5, characterized in that, The built-in wavefront adjustment module (29) can realize the function of rotating and translating the test wavefront; facing the light propagation direction, the first beam rotator (19) is rotated counterclockwise around the optical axis. The angle allows the test wavefront to rotate counterclockwise by a factor of 2 around the optical axis in the direction directly opposite to the light propagation direction. Angle; the direction of light propagation reflected from the first reflecting mirror (20), and the distance the first reflecting mirror (20) is translated in the direction perpendicular to the optical axis. This allows the test wavefront to be translated a distance in the same direction perpendicular to the optical axis. .

7. The built-in rotational translation absolute inspection interference device according to claim 4, characterized in that, The image acquisition module includes a second aperture (26), an imaging lens group (27), and an area array detector (28). The linearly polarized light that is converged at the center of the second aperture (26) by the second lens group (25) is imaged onto the target surface of the area array detector (28) by the imaging lens group (27) to obtain a set of phase-shifted interferograms.

8. The built-in rotational translation absolute inspection interference device according to claim 7, characterized in that, The first aperture (16) and the second aperture (26) are located at the front focal plane of the first lens group (17) and the rear focal plane of the second lens group (25), respectively. The rear focal plane of the first lens group (17) and the front focal plane of the second lens group (25) coincide. The first aperture (16) and the second aperture (26) form a conjugate relationship. The center of the first beam rotator (19) and the second beam rotator (21) is located at the coincidence plane of the rear focal plane of the first lens group (17) and the front focal plane of the second lens group (25). The second aperture (26) is located at the front focal plane of the imaging lens group (27).

9. A method for measuring surface shape based on the apparatus according to any one of claims 1 to 8, characterized in that, The method includes: Step 1: The short coherent polarization light source module emits a pair of light sources with optical path difference. Orthogonally linearly polarized light, each of which generates two optical path differences when passed through a large-aperture Fizeau interferometer system. The reference collimated light and the test collimated light, and the four linearly polarized lights are controlled by the built-in wavefront adjustment module and then emitted into the image acquisition module. Step 2: Rotate and adjust the first half-wave plate (2) so that the intensity of the two beams split by the first polarizing beam splitter (3) of the output light from the short coherence laser (1) is similar; rotate and adjust the first quarter-wave plate (4) so ​​that the intensity of the output light after passing through the first plane mirror (5) and the first polarizing beam splitter (3) reaches the maximum value; rotate and adjust the second quarter-wave plate (6) so that the intensity of the output light after passing through the second plane mirror (7) and the first polarizing beam splitter (3) reaches the maximum value; rotate and adjust the second half-wave plate (8) so that the intensity of the two beams split by the second polarizing beam splitter (18) is similar; Step 3: Move the first plane mirror (5) and the second plane mirror (7) parallel to the optical axis to change the relative distance between them and the first polarizing beam splitter (3) to perform optical path matching, so that the contrast of the interference pattern fringes collected on the area array detector (28) reaches the user-defined optimal value. At this time, the separation of the reference wavefront and the test wavefront is realized. Fine-tune the linear polarizer (24) until the fringe contrast reaches the user-defined optimal value. Adjust the attitude of the reference mirror (14) and the test mirror (15), and set the exposure time of the area array detector (28) so that the interference pattern fringes are adjusted to the user-defined optimal state. Step 4: Translate the first plane mirror (5) along the optical axis to perform phase shifting and simultaneously acquire the interference pattern; Step 5: Use the phase decomposition algorithm to solve the phase-shifted interferogram acquired by the array detector (28) to obtain the i-th wavefront shape of the relative interference. , , This represents the total number of wavefront shapes. Step 6: Extract the surface shape obtained in Step 5 using the stress birefringence error correction method. Polarization error included ; Step 7: Calculate the surface shape result obtained in Step 5. Subtract the polarization error obtained in step 6 This allows us to obtain a wavefront shape without polarization error. ; Step 8: Perform the procedure according to the corresponding absolute test method. Second wavefront rotation operation and Second wavefront translation operation, in which... All are non-negative integers, and satisfy the following conditions: , The total number of wavefront shapes; repeat steps 4 to 7 for a total of Second-rate; Step 9, for the information obtained in step 8 wavefront shape Using the corresponding absolute verification algorithm, the absolute surface shape data is obtained. subscript For the face shape number, , This represents the total number of mirror surfaces participating in the test.

10. The surface shape measurement method according to claim 9, characterized in that, The specific process of the stress birefringence error correction method in step 6 is as follows: Step 6-1: After completing steps 1 to 5, obtain the first wavefront shape measurement result, denoted as... ; Step 6-2: Based on the device used in Step 6-1, rotate and adjust the second half-wave plate (8) to reduce the light intensity received by the area array detector (28) until the light intensity returns to the state in Step 6-1. Then stop. After completing Steps 4 and 5, obtain the second wavefront shape measurement result, denoted as... ; Step 6-3, process the wavefront results obtained in step 6-1. And the wavefront results obtained in step 6-2 By subtracting the values, the polarization error can be obtained. .

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