Synchronous equivalent multi-wavelength microscopic interference measurement system and method based on incident angle modulation

Abstract

The invention discloses a synchronous equivalent multi-wavelength microscopic interference measuring method based on incident angle modulation, and belongs to the technical field of measuring instruments. According to the method, under the condition of a single-wavelength light source, multiple groups of interference wavelengths are equivalently constructed by modulating an illumination incident angle, so that the interference measurement range is expanded, and the phase reconstruction precision is improved. According to the system, a blazed phase grating is loaded by using a spatial light modulator, a plurality of illumination light beams with different incident angles are synchronously generated by regulating and controlling different diffraction orders, so that interference signals corresponding to equivalent wavelengths are formed on the surface of a sample, and interference information of each channel is synchronously acquired through polarization regulation and control. The system does not need multiple light sources or a wide-spectrum light source, is simple in structure, is good in measurement synchronism, is large in measurement range, is high in stability, and is high in anti-interference capability.

Description

Technical Field

[0001] This invention belongs to the field of laser measurement instrument technology, specifically relating to a synchronous equivalent multiwavelength micro-interference measurement system and method based on incident angle modulation. Background Technology

[0002] Reflective microinterferometry has been widely used in fields such as three-dimensional morphology detection of micro and nano structures, evaluation of precision machined surfaces, and semiconductor manufacturing due to its advantages such as non-contact operation, high axial resolution, and high measurement accuracy.

[0003] In traditional reflective microinterferometry, a single-wavelength coherent light source is typically used to acquire interference phase information. However, this method is limited by the 2π periodicity of the phase mode, resulting in a limited unambiguous measurement range. When the sample under test has a large height abrupt change or a step structure, phase ambiguity is easily generated, leading to measurement failure.

[0004] To extend the measurement range, existing technologies typically employ real multi-wavelength interferometry or broadband interferometry, which uses multiple light sources or broadband light sources to construct multiple interference wavelengths, thereby achieving phase unfolding. However, these methods often suffer from problems such as complex system structure, difficulty in ensuring optical path consistency, high requirements for spectral stability, and poor multi-wavelength synchronization, making them unsuitable for precision measurements requiring high stability and high synchronization.

[0005] In addition, although some multi-angle illumination micro-measurement methods can improve measurement sensitivity or enhance information dimension, they do not combine multi-angle illumination with equivalent multi-wavelength interference mechanisms, making it difficult to achieve synchronous acquisition of multi-wavelength interference information under single-wavelength conditions.

[0006] Therefore, there is an urgent need for a novel micro-interferometric measurement system that can simultaneously construct multiple equivalent interference wavelengths by modulating the incident illumination angle while maintaining the structural simplicity of a single-wavelength system, thereby expanding the measurement range and improving measurement stability. Summary of the Invention

[0007] The purpose of this invention is to overcome the limitations of single-wavelength microinterferometry range and the complexity and poor synchronization of multi-wavelength systems in existing technologies. It provides a synchronous equivalent multi-wavelength microinterferometry system and method based on incident angle modulation. By modulating the incident angle of illumination under single-wavelength illumination conditions, the interference phase is physically equivalent to different interference wavelengths, thus enabling multi-wavelength interferometry measurements without the need for multiple light sources or broadband light sources. Simultaneously, through a spatial light modulator and a polarization interference structure, synchronous acquisition of interference information from multiple incident angles is achieved, improving the system's measurement stability and anti-interference capability.

[0008] The technical solution to achieve the purpose of this invention is as follows: a synchronous equivalent multi-wavelength micro-interferometry system based on incident angle modulation, comprising an incident angle modulation subsystem and a micro-interferometry subsystem, wherein the incident angle modulation subsystem includes a laser, a collimating lens, a first polarizer, a spatial light modulator, a beam splitter, a second polarizer, and a focusing lens; the micro-interferometry subsystem includes a half-wave plate, a polarizing beam splitter, a first quarter-wave plate, a second quarter-wave plate, a test arm objective lens, a reference arm objective lens, a reference mirror, a test object, a third quarter-wave plate, a tube mirror, a first imaging lens, a second imaging lens, and a polarizing CMOS camera.

[0009] In the incident angle modulation subsystem, the diverging light emitted from the laser passes through a collimating lens and then through a first polarizer to form linearly polarized light. It is incident at a 45° angle with the beam splitter surface of the beam splitter. The reflected light is incident on the spatial light modulator and, after being modulated by a simulated grating on the spatial light modulator, emits 0th-order light and +1st-order light. The two beams pass through the beam splitter, then through a second polarizer, and are focused by a focusing lens onto the back focal plane of the test arm objective and the reference arm objective.

[0010] In the micro-interferometry subsystem, the beam of light passing through the focusing lens reaches the polarization beam splitter after passing through the half-wave plate. The beam splitter splits the beam into reflected light and transmitted light with mutually perpendicular polarization directions at the splitting surface of the polarization beam splitter. The reflected light is the coherent reference light, and the transmitted light is the coherent test light. The coherent test light passes through the second quarter-wave plate and is incident on the test arm objective lens. After reaching the surface of the test object, it is reflected. The coherent test light carrying the surface shape information of the test object passes through the test arm microscope objective lens and the second quarter-wave plate to reach the polarization beam splitter. It is reflected at the splitting surface of the polarization beam splitter, passes through the third quarter-wave plate and the tube lens, and is imaged on the back focal plane of the tube lens. The image then passes through the first imaging lens and the second imaging lens and is imaged on the back focal plane of the second imaging lens. The beam then travels a certain distance to reach the target surface of the polarization CMOS camera.

[0011] After being reflected at the beam-splitting surface of the beam-splitting prism, the coherent reference light passes through the second quarter-wave plate and is incident on the reference arm objective lens to reach the surface of the reference mirror. After being reflected by the reference mirror, it passes through the reference arm objective lens and the first quarter-wave plate to reach the polarizing beam-splitting prism. After passing through the beam-splitting surface of the polarizing beam-splitting prism, it passes through the third quarter-wave plate and the tube lens and is imaged on the back focal plane of the tube lens. The image then passes through the first imaging lens and the second imaging lens and is imaged on the back focal plane of the second imaging lens. After the beam travels a certain distance, it reaches the target surface of the polarizing CMOS camera and interferes with the coherent test light carrying the surface shape information of the test object.

[0012] A synchronous equivalent multiwavelength microinterferometry method based on incident angle modulation, comprising the following steps:

[0013] Step 1: The monochromatic light emitted from the laser is collimated by a collimating lens to generate collimated light. After being reflected by a beam splitter, it is incident directly on the spatial light modulator. The blazed phase grating loaded on the spatial light modulator is adjusted to adjust the +1 order beam to the target angle.

[0014] Step 2: Adjust the first polarizer to adjust the polarization state of the linearly polarized light incident on the spatial light modulator, so that the intensity of the 0th order light and the +1st order light emitted from the spatial light modulator are the same.

[0015] Step 3: Place the polarization CMOS camera on the back focal plane of the second imaging lens, and adjust the test object and reference mirror in sequence to make the test object and reference mirror clearly imaged on the polarization CMOS camera.

[0016] Step 4: Adjust the position of the polarization CMOS camera until the defocused images illuminated by beams of light emitted from the spatial light modulator at different angles can be simultaneously covered by the target surface of the polarization CMOS camera.

[0017] Step 5: Adjust the second polarizer and half-wave plate to maintain good contrast in the interference fringes displayed in the polarization CMOS camera.

[0018] Step 6: The polarization CMOS camera acquires multiple frames of interferograms for analysis to detect the surface morphology of the test object.

[0019] Compared with the prior art, the significant advantages of this invention are:

[0020] (1) No need for multiple light sources. Under single-wavelength light source conditions, equivalent multi-wavelength interference is achieved by incident angle modulation. The system structure is simple and highly stable.

[0021] (2) The measurement range is significantly extended: by constructing multiple equivalent synthetic wavelengths, the phase ambiguity limitation of single-wavelength interference is effectively overcome, making it suitable for the measurement of large height changes and step morphology.

[0022] (3) A polarization phase-shifting interferometry module is introduced, including a quarter-wave plate and a polarization camera. Four phase-shifting interferograms are acquired simultaneously in a single exposure to achieve real-time synchronous measurement, thereby further improving the imaging speed and phase measurement accuracy. Attached Figure Description

[0023] Figure 1 This is the optical path diagram of the synchronous equivalent multiwavelength micro-interferometry system of the present invention. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] The technical solutions of the various embodiments of the present invention can be combined with each other, but only if they can be implemented by those skilled in the art. When 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.

[0027] 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.

[0028] Combination Figure 1 A synchronous equivalent multi-wavelength micro-interferometry system based on incident angle modulation is disclosed. The entire system is divided into two parts: an incident angle modulation subsystem and a micro-interferometry subsystem arranged sequentially along the optical path. The incident angle modulation subsystem includes a laser 1, a collimating lens 2, a first polarizer 3, a spatial light modulator 4, a beam splitter 5, a second polarizer 6, and a focusing lens 7. The micro-interferometry subsystem includes a half-wave plate 8, a polarizing beam splitter 9, a first quarter-wave plate 10, a second quarter-wave plate 11, a test arm objective lens 12, a reference arm objective lens 13, a reference mirror 14, a test object 15, a third quarter-wave plate 16, a tube mirror 17, a first imaging lens 18, a second imaging lens 19, and a polarizing CMOS camera 20.

[0029] In the incident angle modulation subsystem, the diverging light emitted from laser 1 passes through collimating lens 2 and then through first polarizer 3 to form linearly polarized light. This linearly polarized light is incident at a 45° angle to the beam-splitting surface of beam-splitting prism 5. The reflected light then enters spatial light modulator 4, where it is modulated by a simulated grating to produce 0th-order and +1st-order beams. These two beams pass through beam-splitting prism 5, then through second polarizer 6, and are focused by focusing lens 7 onto the back focal planes of test arm objective 12 and reference arm objective 13. By loading a blazed phase grating onto spatial light modulator 4, most of the diffraction energy is concentrated at the specified diffraction orders. This ensures efficient light energy utilization while precisely controlling the incident angle of the emitted beam, providing a foundation for subsequent construction of equivalent multi-wavelength interference conditions.

[0030] In the micro-interferometer subsystem, the beam passing through the focusing lens 7 passes through the half-wave plate 8 and reaches the polarization beam splitter 9. The beam splitter 9 splits the beam into reflected and transmitted beams with mutually perpendicular polarization directions. The reflected beam is the coherent reference beam, and the transmitted beam is the coherent test beam. The coherent test beam passes through the second quarter-wave plate 11 and is incident on the test arm objective lens 12. After reaching the surface of the test object 15, it is reflected. The coherent test beam carrying the surface shape information of the test object 15 passes through the test arm microscope objective lens 12 and the second quarter-wave plate 11 and reaches the polarization beam splitter 9. It is reflected at the beam splitter surface of the polarization beam splitter 9, passes through the third quarter-wave plate 16 and the tube lens 17, and is imaged on the back focal plane of the tube lens. The image then passes through the first imaging lens 18 and the second imaging lens 19 and is imaged on the back focal plane of the second imaging lens 19. The beam then travels a certain distance and reaches the target surface of the polarization CMOS camera 20.

[0031] After being reflected at the beam-splitting surface of the beam-splitting prism 9, the coherent reference light passes through the second quarter-wave plate 10 and is incident on the reference arm objective lens 13 to reach the surface of the reference mirror 14. After being reflected by the reference mirror 14, it passes through the reference arm objective lens 13 and the first quarter-wave plate 10 to reach the polarizing beam-splitting prism 9. After passing through the beam-splitting surface of the polarizing beam-splitting prism 9, it passes through the third quarter-wave plate 16 and the tube mirror 17 and is imaged on the back focal plane of the tube mirror. The image then passes through the first imaging lens 18 and the second imaging lens 19 and is imaged on the back focal plane of the second imaging lens 19. After being transmitted for a certain distance, the beam reaches the target surface of the polarizing CMOS camera 20 and interferes with the coherent test light carrying the surface shape information of the test object 15.

[0032] The phase grating loaded on the spatial light modulator 4 is a blazed phase grating, used to control the diffraction angle of a specified diffraction order.

[0033] The spatial light modulator 4 is selective in polarization state, modulating only linearly polarized light with a specified polarization direction.

[0034] The period and phase slope of the blazed phase grating are designed according to the required equivalent wavelength range so that the incident angles corresponding to different diffraction orders meet the equivalent multi-wavelength interference conditions.

[0035] The first polarizer 3, the second polarizer 6, the half-wave plate 8, and the polarizing beam splitter 9 together realize the polarization control function, which is used to distinguish the polarization and balance the energy of the interference light corresponding to different diffraction orders.

[0036] Different orders of light emitted from the spatial light modulator 4 are focused at the back focal planes of the test arm objective 12 and the reference arm objective 13 to form point light sources. Based on the diffraction angles of the different orders of diffracted light, different lateral displacements are generated at the back focal planes. Since the position of the back focal plane of the objective lens corresponds one-to-one with the incident angle of the illumination light, the lateral displacement of the point light source at the back focal plane essentially reflects the change in the illumination angle. Therefore, by controlling the distribution position of the point light source at the back focal plane, precise modulation of the illumination angle of the test object 15 can be achieved. By changing the illumination angle, the interference phase of the test object 15 is modulated with the change in the incident angle, thereby obtaining interference phase information corresponding to different equivalent wavelengths under single-wavelength illumination conditions.

[0037] When the illumination angle of test object 15 is changed, the optical path difference will change with the incident illumination angle, and the interference phase will change with the optical path difference. For reflective interferometry, the optical path difference OPD can be expressed as follows when using different illumination angles θ:

[0038] ,

[0039] Where H is the height difference between test object 15 and reference mirror 14.

[0040] In interferometry, phase The relationship between optical path difference (OPD) and optical path difference (OPD) is as follows:

[0041] ,

[0042] in The center wavelength of the laser emitted by laser 1.

[0043] Furthermore, the phase under oblique incidence as follows:

[0044] ,

[0045] The formula is physically equivalent to changing the wavelength of the light source to:

[0046] ,

[0047] in, The equivalent wavelength is obtained when illuminating the test object 15 and the reference mirror 14 using an illumination angle θ. Therefore, under single physical wavelength illumination conditions, by changing the illumination incident angle, an equivalent measurement effect to multi-wavelength interference can be obtained in interferometry, thereby achieving an effective extension of the measurement range without introducing multiple light sources or broadband light sources.

[0048] θ represents the angle of incidence of the illumination light relative to the normal directions of the test object 15 and the reference mirror 14.

[0049] For a one-dimensional blazed grating loaded on the spatial light modulator 4, diffracted light of different orders will be emitted. For ±1 order diffracted light, we can obtain:

[0050] ,

[0051] in, is the diffraction angle when the positive and negative first-order diffracted light exits from the spatial light modulator 4, N is the grating period on the spatial light modulator 4, and p is the pixel size on the spatial light modulator 4. After passing through the focusing lens 7 with a focal length of f, the ±1st-order diffracted light forms lateral displacements on the back focal planes of the reference arm objective 13 and the test arm objective 12, respectively. The point light source, the focal length of both the reference arm objective 13 and the test arm objective 12 is f. obj Then the diffraction angle of the ±1st order diffracted light With lateral displacement have:

[0052] ,

[0053] Substitution ,have

[0054] ,

[0055] Lateral displacement of the point light source at the back focal plane of the objective lens It satisfies a geometric relationship with θ:

[0056] ,

[0057] Substitution We can obtain:

[0058] ,

[0059] Based on equivalent wavelength The formula can ultimately achieve the equivalent wavelength. The relationship between the number of different grating periods loaded on the spatial light modulator 4:

[0060] ,

[0061] It can be seen that by changing the period parameters of the blazed grating loaded on the spatial light modulator 4, the equivalent wavelength can be continuously or discretely tunable without changing the structure of the optical system, thereby improving the adaptability of the system in different measurement tasks.

[0062] The imaging acquisition module, consisting of the first imaging lens 18, the second imaging lens 19, and the polarization CMOS camera 20, is set to a defocus acquisition mode, which separates the interference information corresponding to different incident angles in the spatial domain to avoid spatial aliasing of multi-angle interference information.

[0063] The defocus interference information acquired by the polarization CMOS camera 20 is used to calculate the complex amplitude information of the focal plane through a diffraction transmission algorithm.

[0064] Combination Figure 1 A synchronous equivalent multiwavelength micro-interferometry method based on incident angle modulation is described below:

[0065] Step 1: The monochromatic light emitted from laser 1 is collimated by collimating lens 2, and after being reflected by beam splitter prism 5, it is incident on spatial light modulator 4. The blazed phase grating loaded on spatial light modulator 4 is adjusted to adjust the +1 order beam to the target angle.

[0066] Step 2: Adjust the first polarizer 3 to adjust the polarization state of the linearly polarized light incident on the spatial light modulator 4, so that the intensity of the 0th order light and the +1st order light emitted from the spatial light modulator 4 are the same.

[0067] Step 3: Place the polarization CMOS camera 20 on the back focal plane of the second imaging lens 19, and adjust the test object 15 and the reference mirror 14 in sequence so that the test object 15 and the reference mirror 14 are clearly imaged on the polarization CMOS camera 20.

[0068] Step 4: Adjust the position of the polarization CMOS camera 20 until the defocused images illuminated by the beams of light emitted from the spatial light modulator 4 at different angles can be simultaneously covered by the target surface of the polarization CMOS camera 20.

[0069] Step 5: Adjust the second polarizer 6 and the half-wave plate 8 to maintain good contrast in the interference fringes presented in the polarization CMOS camera 20.

[0070] Step 6: The polarization CMOS camera 20 acquires multiple frames of interferograms for calculation to realize the surface morphology detection of the test object 15.

[0071] The center wavelength of the laser 1 is 632.8 nm.

[0072] The polarization CMOS camera 20 simultaneously acquires four interferograms from different angles. The phase information of each interferogram is first calculated:

[0073] ,

[0074] in This represents the interference phase difference corresponding to the m-th incident angle, where m is the incident angle modulation index. , , , The intensity of the four interferograms is shown. The complex amplitude information of the focal plane can be calculated using the diffraction transmission algorithm based on the collected defocus interference information.

Claims

1. A synchronous equivalent multi-wavelength microinterferometric measurement system based on incident angle modulation, characterized in that: It includes an incident angle modulation subsystem and a micro-interference subsystem. The incident angle modulation subsystem includes a laser (1), a collimating lens (2), a first polarizer (3), a spatial light modulator (4), a beam splitter (5), a second polarizer (6), and a focusing lens (7). The micro-interference subsystem includes a half-wave plate (8), a polarizing beam splitter (9), a first quarter-wave plate (10), a second quarter-wave plate (11), a test arm objective (12), a reference arm objective (13), a reference mirror (14), a test object (15), a third quarter-wave plate (16), a tube mirror (17), a first imaging lens (18), a second imaging lens (19), and a polarizing CMOS camera (20). In the incident angle modulation subsystem, the diverging light emitted from the laser (1) passes through the collimating lens (2) and then through the first polarizer (3) to form linearly polarized light. It is incident at a 45° angle with the beam splitter (5) and its reflected light is incident on the spatial light modulator (4). After being modulated by the simulated grating on the spatial light modulator (4), the 0th order light and the +1st order light are emitted. The two lights pass through the beam splitter (5), pass through the second polarizer (6), and are focused by the focusing lens (7) onto the back focal plane of the test arm objective (12) and the reference arm objective (13) in the micro-interference subsystem. In the micro-interference subsystem, the beam emitted from the focusing lens (7) passes through the half-wave plate (8) and reaches the polarization beam splitter (9). The beam splitter of the polarization beam splitter (9) splits into reflected light and transmitted light with mutually perpendicular polarization directions. The reflected light is the coherent reference light, and the transmitted light is the coherent test light. The coherent test light passes through the second quarter-wave plate (11) and is incident on the test arm objective (12). After reaching the surface of the test object (15), it is reflected. The coherent test light carrying the surface shape information of the test object (15) passes through the test arm microscope objective (12) and the second quarter-wave plate (11) and reaches the polarization beam splitter (9). It is reflected on the beam splitter of the polarization beam splitter, passes through the third quarter-wave plate (16) and the tube lens (17), and is imaged on the back focal plane of the tube lens. The image then passes through the first imaging lens (18) and the second imaging lens (19) and is imaged on the back focal plane of the second imaging lens (19). The beam then travels a certain distance and reaches the target surface of the polarization CMOS camera (20). After the coherent reference light is reflected at the beam splitting surface of the beam splitter (9), it passes through the second quarter-wave plate (10) and is incident on the reference arm objective (13) to reach the surface of the reference mirror (14). After being reflected by the reference mirror (14), it passes through the reference arm objective (13) and the first quarter-wave plate (10) to reach the polarization beam splitter (9). After passing through the beam splitting surface of the polarization beam splitter (9), it passes through the third quarter-wave plate (16) and the tube mirror (17) and is imaged on the back focal plane of the tube mirror. The image then passes through the first imaging lens (18) and the second imaging lens (19) and is imaged on the back focal plane of the second imaging lens (19). After the beam travels a certain distance, it reaches the target surface of the polarization CMOS camera (20) and interferes with the coherent test light carrying the surface shape information of the test object (15).

2. The synchronous equivalent multi-wavelength microinterferometry system according to claim 1, characterized in that: The phase grating loaded on the spatial light modulator (4) is a blazed phase grating, which is used to control the diffraction angle of a specified diffraction order.

3. The synchronous equivalent multi-wavelength microinterferometry system according to claim 2, characterized in that: The spatial light modulator (4) is selective in polarization state and modulates only linearly polarized light with a specified polarization direction.

4. The synchronous equivalent multi-wavelength microinterferometry system according to claim 2, characterized in that: The period and phase slope of the blazed phase grating are designed according to the required equivalent wavelength range so that the incident angles corresponding to different diffraction orders meet the equivalent multi-wavelength interference conditions.

5. The synchronous equivalent multi-wavelength microinterferometry system according to claim 1, characterized in that: The first polarizer (3), the second polarizer (6), the half-wave plate (8), and the polarizing beam splitter (9) work together to achieve polarization control, which is used to distinguish the polarization and balance the energy of the interference light corresponding to different diffraction orders.

6. The synchronous equivalent multi-wavelength microinterferometry system according to claim 1, characterized in that: Different orders of light emitted from the spatial light modulator (4) will be focused on the back focal plane of the test arm objective (12) and the reference arm objective (13) to form point light sources. According to the diffraction angle of the diffracted light of different orders, different lateral displacements will be formed on the back focal plane, thereby changing the illumination angle for the test object (15). By changing the illumination angle, the interference phase will be modulated as the incident angle changes, and interference phase information corresponding to different equivalent wavelengths will be obtained under single-wavelength illumination conditions.

7. The synchronous equivalent multi-wavelength microinterferometry system according to claim 6, characterized in that: When the illumination angle of the test object (15) is changed, the optical path difference will change with the incident illumination angle, and the interference phase will change with the optical path difference. When different illumination angles θ are used, the optical path difference OPD is expressed as: ， Where H is the height difference between the test object (15) and the reference mirror (14); In interferometry, phase The relationship between optical path difference (OPD) and optical path difference (OPD) is as follows: ， in, The center wavelength of the laser emitted by the laser (1); Furthermore, the phase under oblique incidence as follows: ， In the above formula, it is physically equivalent to changing the wavelength of the light source to: ， in, The equivalent wavelength obtained when illuminating the test object (15) and the reference mirror (14) with an illumination angle θ; θ represents the angle of incidence of the illuminating light relative to the normal direction of the test object (15) and the reference mirror (14); For a one-dimensional blazed grating loaded on a spatial light modulator (4), diffracted light of different orders will be emitted. For ±1 order diffracted light, we get: ， in, The positive and negative first-order diffracted light are the diffraction angles when they exit the spatial light modulator (4), N is the grating period on the spatial light modulator (4), and p is the pixel size on the spatial light modulator (4); after passing through the focusing lens (7) with a focal length of f, the ±1st-order diffracted light forms lateral displacements on the back focal planes of the reference arm objective (13) and the test arm objective (12), respectively. The point light source, the focal length of the reference arm objective (13) and the test arm objective (12) are both f. obj Then the diffraction angle of the ±1st order diffracted light With lateral displacement have: ， Substitution ,have ， Lateral displacement of the point light source at the back focal plane of the objective lens It satisfies a geometric relationship with θ: ， Substitution We can obtain: ， Based on equivalent wavelength The formula can ultimately achieve the equivalent wavelength. The relationship between the number of different grating periods loaded on the spatial light modulator (4): 。 8. The synchronous equivalent multi-wavelength microinterferometry system according to claim 1, characterized in that: The imaging acquisition module, consisting of the first imaging lens (18), the second imaging lens (19) and the polarization CMOS camera (20), is set to defocus acquisition mode so that the interference information corresponding to different incident angles is separated in the spatial domain, so as to avoid spatial aliasing of multi-angle interference information.

9. A measurement method based on the synchronous equivalent multi-wavelength microinterferometry system according to any one of claims 1-8, characterized in that, The steps are as follows: Step 1: The monochromatic light emitted from the laser (1) is collimated by the collimating lens (2), and after being reflected by the beam splitter (5), it is incident on the spatial light modulator (4). The blazed phase grating loaded on the spatial light modulator (4) is adjusted to adjust the +1 order beam to the target angle. Step 2: Adjust the first polarizer (3) to adjust the polarization state of the linearly polarized light incident on the spatial light modulator (4) so ​​that the intensity of the 0th order light and the +1st order light emitted from the spatial light modulator (4) is consistent. Step 3: Place the polarization CMOS camera (20) on the back focal plane of the second imaging lens (19), and adjust the test object (15) and the reference mirror (14) in sequence so that the test object (15) and the reference mirror (14) are clearly imaged on the polarization CMOS camera (20); Step 4: Adjust the position of the polarization CMOS camera (20) until the defocused images illuminated by the beams of light emitted from the spatial light modulator (4) at different angles can be simultaneously covered by the target surface of the polarization CMOS camera (20). Step 5: Adjust the second polarizer (6) and the half-wave plate (8) to maintain good contrast in the interference fringes presented in the polarization CMOS camera (20); Step 6: The polarization CMOS camera (20) acquires multiple frames of interferograms for calculation to realize the surface morphology detection of the test object (15).

10. The measurement method of the synchronous equivalent multi-wavelength microinterferometry system according to claim 9, characterized in that: In step six, the polarization CMOS camera (20) simultaneously acquires four interferograms at different angles. The phase information of each interferogram at each angle is first calculated: ， in This represents the interference phase difference corresponding to the m-th incident angle. , , , The intensity of the four interferograms; The collected defocus interference information is used to calculate the complex amplitude information of the focal plane using a diffraction transmission algorithm.

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