Dynamic interference measuring device based on biprism interferometer configuration

Abstract

The invention discloses a dynamic interference measurement device based on biprism interferometer configuration, which is characterized in that a narrow linewidth double-frequency heterodyne light source generates two light beams, one light beam is coupled into a first single-mode polarization maintaining optical fiber to serve as reference light, and the reference light is reflected by a first beam splitter prism to reach an imaging mirror; the other beam of light generated by the narrow-linewidth double-frequency heterodyne light source is coupled into a second single-mode polarization maintaining optical fiber to serve as measuring light, and is reflected to the standard lens through a second beam splitter prism; the standard mirror emits high-quality spherical waves, and the spherical waves reach the to-be-detected mirror, return to the standard mirror, the second beam splitter prism, the first beam splitter prism and the imaging mirror along the original path of the to-be-detected mirror, and reach the detector after being collimated by the imaging mirror; the measuring light and the reference light generate interference in the detector, and the surface shape of each element is calibrated through an interference measurement method. The device can adapt to various light sources such as a narrow linewidth light source and a short coherence light source, can directly calibrate the surface shape of each element through an interference method, and has strong applicability in absolute measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of interferometry, and particularly to a dynamic interferometric measuring device based on a biprism interferometer configuration. Background Art

[0002] Interferometric measurement has the characteristics of high precision, non-contact, and fast response speed, and is widely used in the fields of surface shape of components and detection of transmitted wavefronts, providing an important guarantee for the processing of high-precision optical components. Currently, the basic structures of interferometric measurement include Fizeau, Twyman-Green, Mach-Zehnder structures, etc.

[0003] Currently, the full-field heterodyne phase-shifting technology is widely used in the fields of interferometric measurement such as surface shape and transmitted wavefront. When applied to a Fizeau interferometer, short coherence technology is mainly adopted, the optical path matching is complex, and the measurement applicability is not wide, and it cannot be applied to the direct measurement of aspherical components and components with large curvature radius and large aperture, etc.; when applied to the Twyman-Green and Mach-Zehnder structures, there are influences of parasitic waves and crosstalk clutter introduced by parallel optical paths and parallel plates, which have an impact on the measurement accuracy and repeatability. There is a reference mirror in the structure, which will introduce the influence of the reference mirror surface shape and affect the measurement accuracy. The scheme is limited in absolute measurement. Summary of the Invention

[0004] The purpose of the present invention is to provide a dynamic interferometric measuring device based on a biprism interferometer configuration. This device can adapt to various light sources such as narrow-linewidth light sources and short-coherence light sources, taking into account the advantages of both light sources. At the same time, there is no influence of the reference mirror surface shape on the measurement result accuracy, and the surface shape of each component can be directly calibrated by the interferometric method, and it has strong applicability in absolute measurement.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A dynamic interferometric measuring device based on a biprism interferometer configuration, the device includes a narrow-linewidth dual-frequency heterodyne light source, a first single-mode polarization-maintaining optical fiber, a first beam-splitting prism, an imaging mirror, a detector, a second single-mode polarization-maintaining optical fiber, a second beam-splitting prism, and a reference mirror, wherein:

[0007] The narrow-linewidth dual-frequency heterodyne light source generates two beams of light, one of which is coupled into the first single-mode polarization-maintaining optical fiber as the reference light, and reaches the imaging mirror after being reflected by the first beam-splitting prism; the output end of the first single-mode polarization-maintaining optical fiber is located at the mirror image position of the focus of the imaging mirror relative to the beam-splitting surface of the first beam-splitting prism, so that the reference light reaching the detector is collimated light;

[0008] Another beam of light generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization-maintaining fiber as the measurement light, and reaches the reference mirror after being reflected by the second beam splitter prism; the output end face of the second single-mode polarization-maintaining fiber is located at the mirror image position of the designed incident point of the reference mirror relative to the reflecting surface of the second beam splitter prism to ensure the effective F number of the reference mirror.

[0009] The reference mirror emits a high-quality spherical wave, which reaches the mirror under test and returns to the reference mirror and the second beam splitter prism along the original path; the transmitted beam passing through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, passes through the first beam splitter prism and then reaches the imaging mirror, and after being collimated by the imaging mirror, reaches the detector. The position of the convergence point is at the focal point of the imaging mirror, so that the measurement light reaching the detector is collimated light.

[0010] The measurement light and the reference light interfere at the detector, and the surface shapes of each component are calibrated by the method of interference measurement.

[0011] A dynamic interference measurement device based on the configuration of a double prism interferometer, the device includes a narrow linewidth dual-frequency heterodyne light source, a first single-mode polarization-maintaining fiber, a first beam splitter prism, an imaging mirror, a detector, a second single-mode polarization-maintaining fiber, a second beam splitter prism, a reference mirror, wherein:

[0012] The narrow linewidth dual-frequency heterodyne light source generates two beams of light, one of which is coupled into the first single-mode polarization-maintaining fiber as the reference light and reaches the imaging mirror after being reflected by the first beam splitter prism; the output end of the first single-mode polarization-maintaining fiber is located at the mirror image position of the focal point of the imaging mirror relative to the splitting surface of the first beam splitter prism, so that the reference light reaching the detector is collimated light.

[0013] Another beam of light generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization-maintaining fiber as the measurement light, and reaches the reference mirror after being reflected by the second beam splitter prism; the output end face of the second single-mode polarization-maintaining fiber is located at the mirror image position of the designed incident point of the reference mirror relative to the reflecting surface of the second beam splitter prism to ensure the effective F number of the reference mirror.

[0014] The reference mirror emits a high-quality spherical wave, which reaches the mirror under test and returns to the reference mirror and the second beam splitter prism along the original path; the transmitted beam passing through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, passes through the first beam splitter prism and then reaches the imaging mirror, and after being collimated by the imaging mirror, reaches the detector. The position of the convergence point is at the focal point of the imaging mirror, so that the measurement light reaching the detector is collimated light.

[0015] The device also includes a quarter-wave plate and a polarizer. By cooperating with the quarter-wave plate through the beam splitter prism, the polarization state of the measurement light is matched to be converted from the S polarization state to the P polarization state, improving the energy utilization rate, and cooperating with the polarizer to complete the interference of the measurement light and the reference light, wherein:

[0016] The reference light exits from the first single-mode polarization-maintaining optical fiber, is reflected by the first beam splitter prism, passes through the polarizer and the imaging lens, and reaches the detector;

[0017] The measurement light exits from the second single-mode polarization-maintaining optical fiber, is reflected by the second beam splitter prism, passes through the quarter-wave plate and the reference mirror and then reaches the mirror under test; the light reflected back by the mirror under test passes through the reference mirror and the quarter-wave plate again, and the polarization state is converted to the P polarization state; then it transmits through the second beam splitter prism and the first beam splitter prism, and the polarizer converts the polarization state to be the same as that of the reference light; then it passes through the imaging lens and reaches the detector, and interferes with the reference light at the detector, and the surface shapes of each component are calibrated by the method of interference measurement.

[0018] As can be seen from the technical solution provided by the present invention above, the above device can adapt to various light sources such as narrow-linewidth light sources and short-coherence light sources, take into account the advantages of both light sources, and at the same time there is no influence of the reference mirror surface shape on the measurement result accuracy. The surface shapes of each component can be directly calibrated by the interference method, and it has strong applicability in absolute measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic structural diagram of a dynamic interference measurement device based on a double prism interferometer configuration provided by an embodiment of the present invention;

[0021] Figure 2 It is a schematic internal structure diagram of a narrow-linewidth dual-frequency heterodyne light source according to an embodiment of the present invention;

[0022] Figure 3 It is a schematic structural diagram of a device using a cascaded prism replacement according to an embodiment of the present invention;

[0023] Figure 4 It is a schematic structural diagram of another device using a cascaded prism replacement according to an embodiment of the present invention;

[0024] Figure 5 It is a schematic structural diagram of another structure of the device according to an embodiment of the present invention;

[0025] Figure 6 It is a schematic structural diagram of the device when the mirror under test is a planar component according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, which does not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0027] As Figure 1 shown in the structural schematic diagram of the dynamic interference measurement device based on the double prism interferometer configuration provided by the embodiment of the present invention, the device includes a narrow linewidth dual-frequency heterodyne light source 1, a first single-mode polarization-maintaining fiber 2, a first beam splitting prism 3, an imaging mirror 4, a detector 5, a second single-mode polarization-maintaining fiber 6, a second beam splitting prism 7, and a reference mirror 8, where:

[0028] The narrow linewidth dual-frequency heterodyne light source 1 generates two beams of light. One beam of light is coupled into the first single-mode polarization-maintaining fiber 2 as the reference light, and after being reflected by the first beam splitting prism 3, it reaches the imaging mirror 4; the output end of the first single-mode polarization-maintaining fiber 2 is located at the mirror image position of the focus of the imaging mirror 4 relative to the beam splitting surface of the first beam splitting prism 3, so that the reference light reaching the detector 5 is collimated light;

[0029] The other beam of light generated by the narrow linewidth dual-frequency heterodyne light source 1 is coupled into the second single-mode polarization-maintaining fiber 6 as the measurement light, and after being reflected by the second beam splitting prism 7, it reaches the reference mirror 8; the output end face of the second single-mode polarization-maintaining fiber 6 is located at the mirror image position of the designed incident point of the reference mirror 8 relative to the reflecting surface of the second beam splitting prism 7 to ensure the effective F number of the reference mirror 8;

[0030] The reference mirror 8 emits a high-quality spherical wave, which reaches the mirror under test 9, and returns to the reference mirror 8 and the second beam splitting prism 7 along the original path through the mirror under test 9; the transmitted beam passing through the second beam splitting prism 7 converges first and then diverges, reaches the first beam splitting prism 3, passes through the first beam splitting prism 3 and then reaches the imaging mirror 4, and after being collimated by the imaging mirror 4, it reaches the detector 5. The position of the convergence point is located at the focus of the imaging mirror 4, so that the measurement light reaching the detector 5 is collimated light;

[0031] The measurement light and the reference light interfere at the detector 5, and the surface shapes of each component are calibrated by the method of interference measurement, including the basic surface shapes of the first beam splitting prism 3, the second beam splitting prism 7, the imaging mirror 4, and the mirror under test 9.

[0032] As Figure 2 shown in the internal structural schematic diagram of the narrow linewidth dual-frequency heterodyne light source described in the embodiment of the present invention, the narrow linewidth dual-frequency heterodyne light source 1 includes a laser 10, a polarization-maintaining one-to-two fiber 11, a cascaded acousto-optic frequency shifter 12, and an electrically adjustable fiber attenuator 13, where:

[0033] The laser 10 emits a narrow linewidth beam. After passing through a polarization-maintaining one-to-two fiber 11, it is divided into two paths. One path passes through a cascaded acousto-optic frequency shifter 12, and the other path passes through an electrically adjustable fiber optic attenuator 13.

[0034] The cascaded acousto-optic frequency shifter 12 is formed by cascading and packaging two acousto-optic frequency shifters. After frequency shifting, it generates a beat frequency light with a frequency ranging from a few Hz to several hundred Hz. The frequency-shifted beam is coupled into the second single-mode polarization-maintaining fiber 6 to form a measurement light.

[0035] The electrically adjustable fiber optic attenuator 13 can adjust the light intensity of this path through an electrical signal to match that of the other path, ensuring the contrast of the interference fringes. The output light of the electrically adjustable fiber optic attenuator 13 is coupled into the first single-mode polarization-maintaining fiber 2 to form a reference light.

[0036] In a specific implementation, the measurement light and the reference light interfere at the detector 5. The signal relationship between the two beams of light on the detector 5 is expressed as:

[0037]

[0038] where I 1 is the background light intensity; I 2 is the modulated light intensity; v is the beat frequency; t is the sampling time; is the phase information introduced by the surface shape at the image plane (x, y) position of the mirror 9 to be measured;

[0039] Set the sampling frame rate of the detector 5 to match the beat frequency to complete the acquisition of the measurement images for N + 1-step phase shifting, as shown in the following formula:

[0040]

[0041] where N is the number of phase shifting steps; I(x, y, t i ) is the interference light intensity of the i-th step of phase shifting collected by the detector 5; t i is the sampling time of the detector 5 corresponding to the i-th step of phase shifting;

[0042] The calculated phase information is as shown in the following formula:

[0043]

[0044] In a specific implementation, the method for calculating the phase information can also adopt other multiple phase calculation methods such as N-step phase shifting.

[0045] The above narrow linewidth dual-frequency heterodyne light source 1 can be replaced by a short coherence dual-frequency heterodyne light source. In addition to the heterodyne phase shifting method, mechanical phase shifting, wavelength phase shifting, polarization phase shifting, etc. can also be adopted. For heterodyne phase shifting, frequency shifting methods such as electro-optic frequency shifting can also be used.

[0046] In addition, in a specific implementation, the first beam splitting prism 3 and the second beam splitting prism 7 can be replaced by a cascaded prism, and the convergence and divergence of the light beam are achieved through this cascaded prism. As Figure 3 shown is a schematic structural diagram of the device using a cascaded prism replacement according to an embodiment of the present invention. Figure 3 In:

[0047] Compared with the scheme of the separation prism, although it is more difficult to calibrate the transmitted wavefront error of the light path of the cascaded prism, the cascaded prism has more advantages in controlling the processing error, and the instrument system error can be directly reduced through precision machining, improving the basic measurement accuracy of the instrument; at the same time, the cascaded prism does not need to control the relative position between the prisms, making the alignment more convenient.

[0048] Figure 3 The incident points 2 and 6 of the two light beams entering the cascaded prism are both incident from the bottom up below the cascaded prism, which is easier to control the consistency of the incidence of the two light beams. However, the splitting surfaces of the cascaded prism face in different directions, and the processing accuracy is not as high as that when the splitting surfaces face in the same direction.

[0049] As Figure 4 shown is another schematic structural diagram of the device using a cascaded prism replacement according to an embodiment of the present invention. Figure 4 In: Using another cascaded prism structure also has the advantages of the cascaded prism compared with the separation prism scheme. Figure 4 The splitting surfaces of the cascaded prism face in the same direction, which has more advantages in processing accuracy. However, the incident points 2 and 6 of the two light beams entering the cascaded prism are respectively at the upper and lower ends of the cascaded prism, making it relatively difficult to control the consistency of the two lights.

[0050] In addition, as Figure 5 shown is another schematic structural diagram of the device according to an embodiment of the present invention. The device may further include a quarter-wave plate 14 and a polarizer 15. By matching the quarter-wave plate 14 with the beam splitting prism, the polarization state of the measurement light is converted from the S polarization state to the P polarization state, improving the energy utilization rate, and completing the interference of the measurement light and the reference light in cooperation with the polarizer 15. Refer to Figure 5 :

[0051] The reference light exits from the first single-mode polarization-maintaining optical fiber 2, is reflected by the first beam splitting prism 3, passes through the polarizer 15 and the imaging lens 4, and reaches the detector 5.

[0052] The measurement light exits from the second single-mode polarization-maintaining fiber 6, is reflected by the second beam splitter prism 7, passes through the quarter-wave plate 14 and the reference mirror 8, and then reaches the mirror under test 9; the light reflected back by the mirror under test 9 passes through the reference mirror 8 and the quarter-wave plate 14 again, and the polarization state is converted to the P polarization state; then it transmits through the second beam splitter prism 7 and the first beam splitter prism 3, and the polarization state is converted to be consistent with the reference light through the polarizer 15; then it passes through the imaging lens 4 to reach the detector 5 and interferes with the reference light at the detector 5.

[0053] In a specific implementation, the mirror under test 9 can be a spherical element or a planar element, and the corresponding reference mirror 8 is replaced according to the type of the mirror under test 9. For example, Figure 6 The figure shows a schematic diagram of the device structure when the mirror under test in the embodiment of the present invention is a planar element. By replacing the reference mirror 8, the measurement of the planar element is realized.

[0054] The embodiment of the present invention also provides another dynamic interference measurement device based on the double prism interferometer configuration, as Figure 5 shown. The device includes a narrow linewidth dual-frequency heterodyne light source, a first single-mode polarization-maintaining fiber, a first beam splitter prism, an imaging lens, a detector, a second single-mode polarization-maintaining fiber, a second beam splitter prism, and a reference mirror, where:

[0055] The narrow linewidth dual-frequency heterodyne light source generates two beams of light. One beam of light is coupled into the first single-mode polarization-maintaining fiber as the reference light, and is reflected by the first beam splitter prism to reach the imaging lens; the output end of the first single-mode polarization-maintaining fiber is located at the mirror image position of the focus of the imaging lens relative to the beam splitting surface of the first beam splitter prism, so that the reference light reaching the detector is collimated light;

[0056] The other beam of light generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization-maintaining fiber as the measurement light, and is reflected by the second beam splitter prism to reach the reference mirror; the output end face of the second single-mode polarization-maintaining fiber is located at the mirror image position of the designed incident point of the reference mirror relative to the reflecting surface of the second beam splitter prism to ensure the effective F number of the reference mirror;

[0057] The reference mirror emits a high-quality spherical wave, which reaches the mirror under test, and returns to the reference mirror and the second beam splitter prism along the original path through the mirror under test; the transmitted beam through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, passes through the first beam splitter prism and then reaches the imaging lens, and is collimated by the imaging lens and then reaches the detector. The position of the convergence point is located at the focus of the imaging lens, so that the measurement light reaching the detector is collimated light;

[0058] As Figure 5 shown, the device also includes a quarter-wave plate and a polarizer. The polarization state of the measurement light is matched by the beam splitter prism and the quarter-wave plate to be converted from the S polarization state to the P polarization state, improving the energy utilization rate, and cooperating with the polarizer to complete the interference of the measurement light and the reference light, where:

[0059] The reference light exits from the first single-mode polarization-maintaining optical fiber, is reflected by the first beam splitter prism, passes through the polarizer and the imaging lens, and reaches the detector.

[0060] The measurement light exits from the second single-mode polarization-maintaining optical fiber, is reflected by the second beam splitter prism, passes through the quarter-wave plate and the reference mirror, and then reaches the mirror to be measured; the reflected light from the mirror to be measured passes through the reference mirror and the quarter-wave plate again, and the polarization state is converted to the P polarization state; then it transmits through the second beam splitter prism and the first beam splitter prism, and the polarizer converts the polarization state to be consistent with the reference light; then it passes through the imaging lens and reaches the detector, and interferes with the reference light at the detector, and the surface shapes of each component are calibrated by the method of interference measurement.

[0061] It should be noted that the content not described in detail in the embodiments of the present invention belongs to the prior art well-known to those skilled in the art.

[0062] In summary, the device described in the embodiments of the present invention has the following advantages:

[0063] 1. The structure of this solution can adapt to various light sources such as narrow-linewidth light sources and short-coherence light sources. Using a short-coherence light source can eliminate the influence of other light beams on the measurement results, and using a narrow-linewidth light source can increase the coherence length, adapting to the measurement of large optical path range measured parts and long-focus large-aperture components.

[0064] 2. This solution mainly adopts a divergent optical path, further suppressing the influence of parasitic waves on the measurement results, and avoiding the influence of mixing crosstalk on the measurement results in principle.

[0065] 3. This solution uses a high-quality spherical wave directly emitted by the optical fiber or generated by point diffraction as the emitted reference, avoiding the influence of the reference mirror surface shape on the measurement result accuracy.

[0066] 4. In this solution, the processing accuracy of the control prism or cascaded prism can reach a relatively high measurement accuracy, reducing the system error.

[0067] 5. In the process of building this solution, the surface shapes of each component can be directly calibrated by using the high-quality spherical wave directly emitted by the optical fiber or generated by point diffraction interference, which has strong applicability in absolute measurement.

[0068] As described above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art known to those skilled in the art.

Claims

1. A dynamic interferometric measurement device based on a dual-prism interferometer configuration, characterized in that: The device comprises a narrow-linewidth dual-frequency heterodyne light source, a first single-mode polarization-maintaining optical fiber, a first beam splitter prism, an imaging mirror, a detector, a second single-mode polarization-maintaining optical fiber, a second beam splitter prism, and a standard mirror, wherein: A narrow linewidth dual-frequency heterodyne light source generates two light beams, one of which is coupled into the first single-mode polarization-maintaining fiber as a reference light, and is reflected by the first beam splitter prism to reach the imaging mirror; the output end of the first single-mode polarization-maintaining fiber is located at the mirror image position of the focus of the imaging mirror relative to the beam splitting surface of the first beam splitter prism, so that the reference light reaching the detector is collimated light; Another beam of light generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization-maintaining fiber as the measuring light, and is reflected by the second beam splitter prism to reach the standard mirror; the output end face of the second single-mode polarization-maintaining fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflective surface of the second beam splitter prism, so as to ensure the effective F number of the standard mirror; The standard mirror emits a high-quality spherical wave, which reaches the mirror to be measured, and returns to the standard mirror and the second beam splitter prism through the mirror to be measured; the transmitted light beam passing through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, reaches the imaging mirror after being transmitted through the first beam splitter prism, and reaches the detector after being collimated by the imaging mirror, and the convergence point is located at the focus of the imaging mirror, so that the measurement light reaching the detector is collimated light; The measuring light and the reference light interfere with each other at the detector, and the surface shape of each component is calibrated by the interference measurement method.

2. The dynamic interferometry device based on the dual prism interferometer configuration according to claim 1, characterized in that: The narrow linewidth dual-frequency heterodyne light source comprises a laser, a polarization-maintaining one-to-two optical fiber, a cascaded acousto-optic frequency shifter, and an electrically adjustable optical fiber attenuator, wherein: The laser emits a narrow linewidth beam, which is divided into two paths after passing through a polarization-maintaining one-to-two fiber. One path passes through a cascaded acousto-optic frequency shifter, and the other passes through an electrically adjustable fiber attenuator. The cascaded acousto-optic frequency shifter is a cascade package of two acousto-optic frequency shifters. After frequency shifting, a difference frequency light is generated, with a frequency of several Hz to several hundred Hz. The frequency-shifted light beam is coupled into the second single-mode polarization-maintaining optical fiber to form a measurement light. The electrically adjustable optical fiber attenuator can adjust the light intensity of the light path to match the other path through an electrical signal to ensure the contrast of the interference fringes. The output light of the electrically adjustable optical fiber attenuator is coupled into the first single-mode polarization-maintaining optical fiber to form a reference light.

3. The dynamic interferometry device based on the dual prism interferometer configuration according to claim 1, characterized in that: The measurement light and the reference light interfere with each other at the detector, and the signal relationship between the two beams on the detector is expressed as: Among them, I1 is the background light intensity; I2 is the modulated light intensity; v is the difference frequency; t is the sampling time; The phase information introduced by the surface shape at the image plane (x, y) position of the mirror to be measured; The detector sampling frame rate is set to match the difference frequency to complete the measurement image acquisition of N+1-step phase shift, as shown in the following formula: Where N is the number of phase shift steps; I(x,y,t i ) is the interference light intensity of the i-th phase shift collected by the detector; t i is the sampling moment of the detector corresponding to the i-th phase shift; The calculated phase information As shown in the following formula:

4. The dynamic interferometry device based on the dual prism interferometer configuration according to claim 1, characterized in that: The first beam splitter prism and the second beam splitter prism can be replaced by a cascade prism, through which the convergence and divergence of the light beam can be achieved; Among them, the incident points of the two light beams entering the cascade prism are both below the cascade prism and incident from bottom to top; Alternatively, the incident points of the two light beams entering the cascade prism are respectively at the upper and lower ends of the cascade prism.

5. The dynamic interferometry device based on the dual prism interferometer configuration according to claim 1, characterized in that: The device also includes a quarter wave plate and a polarizer. The polarization state of the measurement light is converted from the S polarization state to the P polarization state by matching the beam splitter prism with the quarter wave plate, thereby improving energy utilization, and cooperating with the polarizer to complete interference of the measurement light and the reference light, wherein: The reference light is emitted from the first single-mode polarization-maintaining optical fiber, reflected by the first beam splitter prism, and reaches the detector through the polarizer and imaging mirror. The measuring light is emitted from the second single-mode polarization-maintaining optical fiber, reflected by the second beam splitter prism, and reaches the mirror to be measured after passing through a quarter-wave plate and a standard mirror; the light is then reflected back by the mirror to be measured, and passes through the standard mirror and a quarter-wave plate again to convert the polarization state to a P polarization state; then it is transmitted through the second beam splitter prism and the first beam splitter prism, and the polarization state is converted to be consistent with the reference light through the polarizer; then it reaches the detector through the imaging mirror, and interferes with the reference light at the detector.

6. The dynamic interferometry device based on the dual prism interferometer configuration according to claim 1, characterized in that: The mirror to be tested is a spherical element or a plane element, and the corresponding standard mirror is replaced according to the type of the mirror to be tested.

7. A dynamic interferometric measurement device based on a dual-prism interferometer configuration, characterized in that: The device comprises a narrow-linewidth dual-frequency heterodyne light source, a first single-mode polarization-maintaining optical fiber, a first beam splitter prism, an imaging mirror, a detector, a second single-mode polarization-maintaining optical fiber, a second beam splitter prism, and a standard mirror, wherein: A narrow linewidth dual-frequency heterodyne light source generates two light beams, one of which is coupled into the first single-mode polarization-maintaining fiber as a reference light, and is reflected by the first beam splitter prism to reach the imaging mirror; the output end of the first single-mode polarization-maintaining fiber is located at the mirror image position of the focus of the imaging mirror relative to the beam splitting surface of the first beam splitter prism, so that the reference light reaching the detector is collimated light; Another beam of light generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization-maintaining fiber as the measuring light, and is reflected by the second beam splitter prism to reach the standard mirror; the output end face of the second single-mode polarization-maintaining fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflective surface of the second beam splitter prism, so as to ensure the effective F number of the standard mirror; The standard mirror emits a high-quality spherical wave, which reaches the mirror to be measured, and returns to the standard mirror and the second beam splitter prism through the mirror to be measured; the transmitted light beam passing through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, reaches the imaging mirror after being transmitted through the first beam splitter prism, and reaches the detector after being collimated by the imaging mirror, and the convergence point is located at the focus of the imaging mirror, so that the measurement light reaching the detector is collimated light; The device also includes a quarter wave plate and a polarizer. The polarization state of the measurement light is converted from the S polarization state to the P polarization state by matching the beam splitter prism with the quarter wave plate, thereby improving energy utilization, and cooperating with the polarizer to complete interference of the measurement light and the reference light, wherein: The reference light is emitted from the first single-mode polarization-maintaining optical fiber, reflected by the first beam splitter prism, and reaches the detector through the polarizer and imaging mirror. The measuring light is emitted from the second single-mode polarization-maintaining optical fiber, reflected by the second beam splitter prism, and reaches the mirror to be measured after passing through a quarter-wave plate and a standard mirror; the light is then reflected back by the mirror to be measured, and again passes through the standard mirror and a quarter-wave plate to convert the polarization state into a P polarization state; then it is transmitted through the second beam splitter prism and the first beam splitter prism, and the polarization state is converted to be consistent with the reference light through the polarizer; then it reaches the detector through the imaging mirror, and interferes with the reference light at the detector, and the surface shape of each component is calibrated by the interference measurement method.

Images