A method for detecting a tilt wavefront of a dual-fiber interference arm by infrared interference

Abstract

The application discloses a kind of tilting wave surface infrared interference detection methods of double optical fiber interference arm, it is related to the field of optical precision measurement.The light emitted by wavelength tunable laser passes through coupler and is divided into two beams, one is directly output by polarization maintaining optical fiber as reference light, the other is incident to optical fiber array and outputs multiple standard spherical waves with different tilt angles as test light, compensates the surface gradient of different regions of the measured surface, thereby reducing the interference fringe density.Both the reference arm and the test arm of the system use optical fiber as an ideal point source generator, which can control the on-off of the point source and reduce the system error introduced by the use of lenses.The light emitted by the test arm optical fiber is all used as test light, which improves the utilization rate of the point source, increases the aperture of the measured surface, and realizes surface shape detection without moving the interference device, reducing the error introduced by mechanical movement.The system uses infrared light as the measurement beam to improve the dynamic measurement range, which can meet the detection of more gradient-changing large-aperture components.

Description

Technical Field

[0001] This invention belongs to the field of optical precision measurement technology, and specifically relates to a tilted wavefront infrared interferometry detection method with dual fiber interferometer arms. Background Technology

[0002] Compared to spherical optical elements, aspherical optical components offer greater design freedom, enabling them to significantly improve optical system performance while meeting the requirements of compactness, miniaturization, and lightweight design in modern optical systems. Therefore, they are gaining increasing importance in fields such as automotive and aerospace. However, high-precision aspherical surface machining relies on high-precision surface shape inspection technology. The large surface gradient, high degree of freedom in surface shape, and lack of rotational symmetry of aspherical surfaces increase the difficulty of high-precision machining and precise inspection.

[0003] The tilted wavefront method, by introducing multiple off-axis interference sources, generates multiple beams of spherical waves with different tilt angles to compensate for the gradients in various local regions of the surface under test. This avoids the introduction of positioning and motion errors, achieving high-precision aspherical surface shape measurement. CN103759668B discloses a "tilted wavefront interferometry system based on a fiber array-type spatial point source array generator." This system uses a fiber array instead of a lens array, emitting high-quality spherical waves with controllable divergence angles. The light emitted from each fiber in the fiber array is guided one-to-one, resulting in higher light energy utilization efficiency than interferometry systems using lens arrays. Furthermore, the on / off state of each fiber can be controlled individually, eliminating the need for a mask to control point source selection. However, measuring aspherical elements with larger apertures and gradients requires designing larger-aperture collimating lens groups and spherical lens groups, which is challenging.

[0004] CN108362222B discloses a "Novel Point Diffraction Interferometry Measurement System Based on Multi-directional Tilt Carrier Frequency," which utilizes an optical fiber array to construct a point diffraction array, generating a wavefront compensation for the surface gradient of the test object using a multi-directional tilt carrier frequency, and measuring the surface profile of aspherical components. However, because a portion of the on-axis point source on the optical fiber array is used as reference light, only a portion of the point source enters the test surface as test light, resulting in low light utilization of the point source for measurement, and limiting the aperture and gradient of the test surface. Summary of the Invention

[0005] This invention proposes a tilted wavefront infrared interferometry detection method using dual fiber interferometer arms. By employing dual fiber interferometer arms, point sources for detection can be generated for different surface shapes under test by controlling the on / off state of the fiber array. This method also improves the utilization rate of the point sources, reduces the need for interferometric lenses, and lowers the introduced wavefront aberrations.

[0006] The technical solution for achieving the present invention is as follows: a tilted wavefront infrared interferometry detection method with dual fiber interferometer arms, comprising the following steps:

[0007] Step 1: Set up the measurement optical path:

[0008] The measurement optical path includes a wavelength-tunable laser, a coupler, a second beam splitter, a first lens, a second lens, a third lens, a CCD, a PC control terminal, a test arm, and a reference arm. The wavelength-tunable laser and the coupler are arranged sequentially along the first optical axis. The wavelength-tunable laser and the coupler are connected through a first polarization-maintaining fiber. The output end of the coupler is connected to the test arm and the reference arm through two first polarization-maintaining fibers, respectively.

[0009] The test arm includes a first optical switch, an optical fiber array, a first beam splitter, and a test surface arranged sequentially along a second optical axis. The coupler is connected to the first optical switch via a first polarization-maintaining fiber, and the first optical switch and the optical fiber array are connected via the first polarization-maintaining fiber.

[0010] The reference arm includes a second optical switch and a second polarization-maintaining fiber arranged sequentially along the third optical axis. The input end of the second optical switch is connected to a coupler through the first polarization-maintaining fiber, and the output end of the second optical switch is connected to a second beam splitter through the second polarization-maintaining fiber.

[0011] The fourth optical axis is sequentially arranged with an aperture stop, a second beam splitter, a first lens, a second lens, a third lens, and a CCD. The reference arm and the test arm are combined through the second beam splitter, and the aperture stop is located on the reflected light path of the first beam splitter. The CCD is connected to the PC control terminal.

[0012] The linearly polarized light emitted from the wavelength-tunable laser is split into two beams by a coupler after being output from the first polarization-maintaining fiber. One beam is used as a reference beam and enters the reference arm, while the other beam enters the test arm. The beam entering the test arm passes sequentially through the first optical switch and the fiber array to form the test beam. The test beam is transmitted through the first beam splitter and then incident on the surface under test. The test beam carrying the surface shape information of the surface under test returns to the first beam splitter and is reflected by the first beam splitter into the fourth optical axis. The test beam carrying the surface shape information of the surface under test passes sequentially along the fourth optical axis through the aperture, the second beam splitter, the first lens, the second lens, and the third lens before being received by the CCD. The reference beam is output from the second optical switch and exits along the second polarization-maintaining fiber to the second beam splitter. It is reflected by the second beam splitter into the fourth optical axis, and then passes sequentially through the first lens, the second lens, and the third lens before being received by the CCD. The CCD acquires a sub-region interferogram carrying the surface shape information of the surface under test and transmits the sub-region interferogram to the PC control terminal.

[0013] Step 2: Based on the surface shape parameters of the surface to be tested, divide the surface to be tested into sub-regions, and determine the point source position parameters and on / off sequence required by the fiber array for surface shape detection based on the parameters of the divided sub-regions.

[0014] Step 3: Turn on the first optical switch on the test arm and the second optical switch on the reference arm, replace the surface under test with a standard spherical mirror, adjust the orientation of the standard spherical mirror, and calibrate the system error of each point source on the fiber array required for the surface under test.

[0015] Step 4: Remove the standard spherical mirror and place it on the surface to be tested. Turn on the wavelength-tunable laser and perform interference detection on the surface shape information of the surface to be tested based on the point source position and on / off sequence obtained in Step 2.

[0016] Step 5: Adjust the center wavelength λ of the wavelength-tunable laser by Δλ, so that its phase changes continuously within a complete cycle by π / 2, π, 3π / 2, and 2π. The CCD continuously acquires four interferograms of the sub-region of the test surface corresponding to each point source.

[0017] Step 6: Decompose the phase of the four interferograms collected for each sub-region of the surface under test, and obtain the enclosed phase of each sub-region.

[0018] Step 7: Correct the backfetch error of the wrapping phase of each sub-region using the backfetch error correction algorithm to obtain the surface information of each sub-region after correcting the backfetch error.

[0019] Step 8: Based on the coordinate positions of each sub-region, stitch together the surface information of each sub-region after correcting the return error to obtain the full-aperture corrected surface information of the entire surface to be measured. Compare the full-aperture corrected surface information with the surface parameters of the surface to be measured to complete the detection of the surface error of the surface to be measured.

[0020] Compared with the prior art, the significant advantages of this invention are:

[0021] (1) Both the reference arm and the test arm of this invention use optical fiber as an ideal point source generator to generate near-ideal point diffraction spherical waves. In this way, there is no need to add a standard compensation spherical lens group in the optical path, avoiding the introduction of a large number of wave aberrations by the standard compensation spherical lens group. At the same time, the utilization rate of the point source is improved, the size of the measurement aperture of the interferometric system is increased, and the surface shape detection can be achieved without moving the interferometric device, reducing the error introduced by mechanical movement.

[0022] (2) The present invention uses infrared light as a measurement beam to improve the dynamic measurement range of the entire system and can meet the detection of large-diameter components with more gradient changes. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the tilted wavefront infrared interferometry optical path of the dual-fiber interferometer arm described in this invention.

[0024] Figure 2 This is a flowchart of a tilted wavefront infrared interferometry detection method with dual fiber interferometer arms according to the present invention.

[0025] In the figure: 1. Wavelength-tunable laser; 2. First polarization-maintaining fiber; 3. Coupler; 4. First optical switch; 5. Fiber array; 6. First beam splitter; 7. Surface under test; 8. Aperture; 9. Second optical switch; 10. Second polarization-maintaining fiber; 11. Second beam splitter; 12. First lens; 13. Second lens; 14. Third lens; 15. CCD; 16. PC control terminal. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] Furthermore, in this invention, descriptions involving "first," "second," etc., 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 that feature.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; "connection" can mean a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible to those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0031] The following section will further introduce the specific implementation method, as well as the technical difficulties and inventive points of this invention, using this design example as an example.

[0032] Combination Figure 2 The present invention discloses a tilted wavefront infrared interferometry detection method for dual fiber interferometer arms, comprising the following steps:

[0033] Step 1, Combining Figure 1 Set up the measurement optical path:

[0034] The measurement optical path includes a wavelength-tunable laser 1, a coupler 3, a second beam splitter 11, a first lens 12, a second lens 13, a third lens 14, a CCD 15, a PC control terminal 16, a test arm, and a reference arm. The wavelength-tunable laser 1 and coupler 3 are sequentially arranged along a first optical axis, connected by a first polarization-maintaining fiber 2. The output of coupler 3 is connected to the test arm and reference arm via two first polarization-maintaining fibers 2. A second optical axis parallel to the first optical axis exists, with a first optical switch 4, an fiber array 5, a first beam splitter 6, and the surface under test 7 sequentially arranged. Coupler 3 is connected to the first optical switch 4 via a first polarization-maintaining fiber 2, and the first optical switch 4 and fiber array 5 are connected via the first polarization-maintaining fiber 2. A third optical axis parallel to the second optical axis exists, along which... The second optical switch 9 and the second polarization-maintaining fiber 10 are distributed in a secondary configuration. The input end of the second optical switch 9 is connected to the coupler 3 through the first polarization-maintaining fiber 2, and the output end of the second optical switch 9 is connected to the second beam splitter 11 through the second polarization-maintaining fiber 10. There is also a fourth optical axis perpendicular to the third optical axis. Along the fourth optical axis, the aperture 8, the second beam splitter 11, the first lens 12, the second lens 13, the third lens 14, and the CCD 15 are distributed in sequence. The reference arm and the test arm are combined through the second beam splitter 11. The aperture 8 is located on the reflected light path of the first beam splitter 6. The CCD 15 is connected to the PC control terminal 16.

[0035] The wavelength-tunable laser 1 emits light along the first optical axis. The polarization direction of the linearly polarized light emitted from the wavelength-tunable laser 1 is consistent with the working optical axes of the first polarization-maintaining fiber 2, coupler 3, first optical switch 4, fiber array 5, second optical switch 9, and second polarization-maintaining fiber 10. The linearly polarized light output from the wavelength-tunable laser 1 is split into two beams by the coupler 3 after being output from the first polarization-maintaining fiber 2. One beam is used as a reference beam and enters the reference arm, while the other beam enters the test arm. The beam entering the test arm is transmitted from the first polarization-maintaining fiber 2 to the first optical switch 4 and fiber array 5. Standard spherical waves with different tilt angles parallel to the first optical axis are emitted from the fiber array 5 to form the test light.

[0036] The test beam from the test arm exits the fiber array 5 along the second optical axis through the first beam splitter 6. After being transmitted through the first beam splitter 6, it is incident on the surface under test 7, detecting the surface shape of different regions of the surface under test. The beam then returns to the first beam splitter 6 carrying the surface shape information of the surface under test 7. The position of the fiber array 5 is based on the center point source of the end face of the fiber array 5, and its light emission direction is consistent with the second optical axis. The positions of the first beam splitter 6 and the fiber array 5 ensure that the light emitted from the outermost point source of the fiber array can completely pass through the beam splitter prism. The test beam carrying the surface shape information of the surface under test 7 returns to the first beam splitter 6, is reflected by the first beam splitter 6, enters the fourth optical axis, is filtered by the aperture 8 of the fourth optical axis to remove stray light, and then passes through the second beam splitter 11. The spatial position of the center of the aperture 8 and the center of the end face of the fiber array 5 is symmetrical about the first beam splitter 6. The beam transmitted through the second beam splitter 11 passes sequentially through the first lens 12, the second lens 13, and the third lens 14 before being received by the CCD 15.

[0037] The reference beam from the reference arm, after being output from the second optical switch 9, is emitted along the second polarization-maintaining fiber 10 and onto the second beam splitter 11. Reflected by the second beam splitter 11, it enters the fourth optical axis. The spatial position of the center of the fiber end face of the second polarization-maintaining fiber 10 and the center of the aperture 8 is symmetrical about the second beam splitter 11. After being reflected by the second beam splitter 11, the reference beam passes sequentially through the first lens 12, the second lens 13, and the third lens 14 before being received by the CCD 15.

[0038] The 4f system, consisting of the second lens 13 and the third lens 14, converges the beam collimated by the first lens 12 and simultaneously images the interferogram onto the CCD 15.

[0039] The wavelength-tunable laser 1 can achieve continuous phase variation of π / 2, π, 3π / 2, and 2π within a complete cycle by controlling the tunability of the center wavelength λ.

[0040] Step 2: Based on the surface shape parameters of the surface to be tested 7, divide the surface to be tested 7 into sub-regions, and determine the point source position parameters and on / off sequence required by the fiber array 5 for surface shape detection based on the parameters of the divided sub-regions.

[0041] The point source parameters required for detecting the 7-sided surface of the test surface are calculated by generating a computational model using a point source array:

[0042] The permissible deviation O of the test light from the reference light is calculated based on the CCD pixel size p and the focal length f of the first lens 12. r radius r:

[0043] ,

[0044] According to the calculated O rGiven the range, the position (x, y, z) of each point on the surface to be measured, and the normal direction corresponding to each point, calculate the measurable point source range Q corresponding to each point on the surface to be measured. r And calculate its centroid. Calculate the location of the point source using the point source filtering method:

[0045] ① Count the number of data points on the test piece that can be measured by all point sources, and mark the one with the most measured data points as H1;

[0046] ② Remove point source H1 and its measurable data points;

[0047] ③ Repeat steps ① to ② for unlabeled point sources until all data points are labeled.

[0048] Finally, the on / off sequence of the point sources is determined by calculating the position of the interferogram of each point source measurement area on the CCD through ray tracing.

[0049] Step 3: Turn on the first optical switch 4 on the test arm and the second optical switch 9 on the reference arm, replace the surface under test 7 with a standard spherical reflector, adjust the orientation of the standard spherical reflector, and calibrate the system error of each point source on the fiber array 5 required for the surface under test 7.

[0050] Step 4: Remove the standard spherical mirror and place it on the surface to be tested 7. Turn on the wavelength tunable laser 1 and perform interference detection on the surface shape information of the surface to be tested 7 according to the point source position and on / off sequence calculated in Step 2.

[0051] Step 5: Adjust the wavelength λ (center wavelength) of the wavelength-tunable laser 1 by changing Δλ so that its phase changes continuously within a complete cycle: π / 2, π, 3π / 2, 2π. The CCD15 continuously acquires four interferograms of the sub-region of the test surface 7 corresponding to each point source.

[0052] Step 6: Decompose the phase of the four interferograms collected for each sub-region of the surface under test 7, and obtain the enclosed phase of each sub-region.

[0053] Step 7: Correct the backfetch error of the wrapping phase of each sub-region using the backfetch error correction algorithm to obtain the surface information of each sub-region after correcting the backfetch error.

[0054] An ideal measurement optical path was constructed using ZEMAX, and a simulation was performed on an ideal detection surface with surface shape error, assuming its surface shape parameters are as follows. Using the ideal detection input, four interferograms for each sub-region are generated. Unwrapping is then performed to obtain the wrapping phase of each sub-region. Let the surface profile parameters of the surface 7 to be measured in the measurement optical path be... The four interferograms of each sub-region of the surface under test 7 are unwrapped to obtain the wrapped phase of the sub-region. It is expressed by the following formula:

[0055] ,

[0056] in , , , All are represented using Zernike polynomials. , , , Time polynomial coefficients, Z j Let N be a polynomial matrix, and N be the number of polynomial terms. The actual reconstructed wavefront of the detection system is used. Zernike coefficient B j As the optimization target, the ideal surface shape error of the surface to be measured is... coefficient Set as an optimization variable, based on the objective function right Perform iterative optimization until... and The optimal solution for the aspherical surface shape coefficient can be obtained when the difference is less than the threshold ε (ε is λ / 20). .

[0057] objective function Defined as:

[0058] ,

[0059] in, To optimize weights.

[0060] Step 8: Based on the coordinate positions of each sub-region, splice and correct the return error of each sub-region to obtain the full-diameter corrected surface information of the entire surface to be tested 7. Compare the full-diameter corrected surface information with the surface parameters of the surface to be tested 7 to complete the detection of the surface error of the surface to be tested.

Claims

1. A tilted wavefront infrared interferometry detection method with dual fiber interferometer arms, characterized in that, The steps are as follows: Step 1: Set up the measurement optical path: The measurement optical path includes a wavelength-tunable laser (1), a coupler (3), a second beam splitter (11), a first lens (12), a second lens (13), a third lens (14), a CCD (15), a PC control terminal (16), a test arm, and a reference arm. The wavelength-tunable laser (1) and the coupler (3) are arranged sequentially along the first optical axis. The wavelength-tunable laser (1) and the coupler (3) are connected through a first polarization-maintaining fiber (2). The output end of the coupler (3) is connected to the test arm and the reference arm through two first polarization-maintaining fibers (2). The test arm includes a first optical switch (4), an optical fiber array (5), a first beam splitter (6) and a test surface (7) arranged sequentially along the second optical axis. The coupler (3) is connected to the first optical switch (4) through the first polarization-maintaining fiber (2), and the first optical switch (4) and the optical fiber array (5) are connected through the first polarization-maintaining fiber (2). The reference arm includes a second optical switch (9) and a second polarization-maintaining fiber (10) arranged sequentially along the third optical axis. The input end of the second optical switch (9) is connected to the coupler (3) through the first polarization-maintaining fiber (2), and the output end of the second optical switch (9) is connected to the second beam splitter (11) through the second polarization-maintaining fiber (10). The fourth optical axis is arranged in sequence as follows: aperture (8), second beam splitter (11), first lens (12), second lens (13), third lens (14), and CCD (15). The reference arm and the test arm are combined through the second beam splitter (11). The aperture (8) is located on the reflected light path of the first beam splitter (6). The CCD (15) is connected to the PC control terminal (16). The linearly polarized light emitted from the wavelength-tunable laser (1) is split into two beams by the coupler (3) after being output through the first polarization-maintaining fiber (2). One beam is used as a reference beam and enters the reference arm, while the other beam enters the test arm. The beam entering the test arm passes through the first optical switch (4) and the fiber array (5) in sequence to form the test beam. The test beam is transmitted through the first beam splitter (6) and then incident on the surface to be tested (7). The test beam carrying the surface shape information of the surface to be tested (7) returns to the first beam splitter (6) and is reflected by the first beam splitter (6) into the fourth optical axis. The test beam carrying the surface shape information of the surface to be tested (7) passes through the aperture (8) in sequence along the fourth optical axis. After passing through the second beam splitter (11), the first lens (12), the second lens (13), and the third lens (14), the light is received by the CCD (15). The reference light is output from the second optical switch (9) and then emitted along the second polarization-maintaining fiber (10) onto the second beam splitter (11). It is reflected by the second beam splitter (11) into the fourth optical axis, and then passes through the first lens (12), the second lens (13), and the third lens (14) in sequence before being received by the CCD (15). The CCD (15) acquires the sub-region interferogram carrying the surface shape information of the surface to be measured (7) and transmits the sub-region interferogram to the PC control terminal (16). Step 2: Based on the surface shape parameters of the surface to be tested (7), divide the surface to be tested (7) into sub-regions, and determine the point source position parameters and on / off sequence required by the fiber array (5) for surface shape detection based on the sub-region parameters. Step 3: Turn on the first optical switch (4) on the test arm and the second optical switch (9) on the reference arm, replace the test surface (7) with a standard spherical mirror, adjust the orientation of the standard spherical mirror, and calibrate the system error of each point source on the fiber array (5) required for the test surface. Step 4: Remove the standard spherical mirror and place it on the surface to be tested (7). Turn on the wavelength tunable laser (1) and perform interference detection on the surface shape information of the surface to be tested (7) according to the point source position and on / off sequence required for the surface to be tested (7) obtained in Step 2. Step 5: Adjust the center wavelength λ of the wavelength tunable laser (1) by Δλ, so that its phase changes continuously within a complete cycle by π / 2, π, 3π / 2, 2π. The CCD (15) continuously acquires four interferograms of the sub-region of the test surface (7) corresponding to each point source. Step 6: Deconstruct the phase of the four interferograms collected for each sub-region of the surface under test (7) to obtain the enclosed phase of each sub-region. Step 7: Correct the backfetch error of the wrapping phase of each sub-region using the backfetch error correction algorithm to obtain the surface information of each sub-region after correcting the backfetch error; Step 8: Based on the coordinate position of each sub-region, splice and correct the return error of each sub-region to obtain the full-diameter corrected surface information of the entire surface to be tested (7). Compare the full-diameter corrected surface information with the surface parameters of the surface to be tested (7) to complete the detection of the surface error of the surface to be tested.

2. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 1, the linearly polarized light emitted from the wavelength-tunable laser (1) is split into two beams after passing through the coupler (3). One beam enters the reference arm and is output by the second polarization-maintaining fiber (10), while the other beam enters the test arm and is output by the fiber array (5). The spatial position of the center of the end face of the fiber array (5) and the center of the aperture (8) is symmetrical about the first beam splitter (6). The spatial position of the center of the fiber end face of the second polarization-maintaining fiber (10) and the center of the aperture (8) is symmetrical about the second beam splitter (11).

3. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 1, the first optical axis is parallel to the second optical axis, the second optical axis is parallel to the third optical axis, and the third optical axis is perpendicular to the fourth optical axis.

4. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 2, the reverse ray tracing and point source filtering algorithm is used to determine the point source position parameters and on / off sequence required by the fiber array (5) for surface shape detection based on the sub-region parameters divided by the surface to be tested (7).

5. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 7, the backfetching phase of each sub-region is corrected for backfetching error using a backfetching error correction algorithm to obtain the surface shape information of each sub-region after backfetching error correction, as follows: The simulation provides an ideal detection surface with surface shape errors, whose surface shape parameters are given as follows: Using the ideal detection input, four interferograms for each sub-region are generated. Unwrapping is then performed to obtain the wrapping phase of each sub-region. Let the surface profile parameters of the surface to be measured (7) in the measurement optical path be... The four interferograms of each sub-region of the surface under test (7) are unwrapped to obtain the wrapped phase of the sub-region. ,calculate and The deviation is corrected through continuous iteration. until and The deviation is less than λ / 20, and finally the surface shape information of each sub-region of the test surface (7) after correcting the return error is obtained.

6. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 8, the surface profile information of each sub-region after splicing and correcting the return error is obtained based on the coordinate position of each sub-region, so as to obtain the full-aperture corrected surface profile information of the entire surface to be measured (7), as follows: Calculate the coordinate position of each sub-region surface profile information after correcting for backlash error in the full-aperture surface profile information, and stitch together the surface profile information of each sub-region after correcting for backlash error based on the coordinate position.

7. The tilted wavefront infrared interferometry detection method with dual fiber interferometer arms as described in claim 1, characterized in that, In step 1, each point source on the point source array generated by the fiber array (5) can cover the entire area on the surface to be tested (7).

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