A dynamic interferometry apparatus based on a two-prism interferometer configuration

Abstract

The application discloses a dynamic interference measuring device based on a double-prism interferometer configuration, a narrow-line-width double-frequency heterodyne light source generates two light beams, one of which is coupled into a first single-mode polarization maintaining optical fiber as reference light, and is reflected to reach an imaging mirror through a first light splitting prism; the other light beam generated by the narrow-line-width double-frequency heterodyne light source is coupled into a second single-mode polarization maintaining optical fiber as measuring light, and is reflected to reach a standard mirror through a second light splitting prism; the standard mirror emits a high-quality spherical wave, the spherical wave reaches a mirror to be measured, returns to the standard mirror, the second light splitting prism, the first light splitting prism and the imaging mirror through the original path of the mirror to be measured, and reaches a detector after collimation by the imaging mirror; the measuring light and the reference light interfere at the detector, and the surface shapes of all elements are calibrated by an interference measurement method. The device can adapt to various light sources such as a narrow-line-width light source and a short-coherence light source, can directly calibrate the surface shapes of all elements by the interference method, and has strong applicability in absolute measurement.

Description

Technical Field

[0001] This invention relates to the field of interferometric measurement technology, and in particular to a dynamic interferometric measurement device based on a double-prism interferometer configuration. Background Technology

[0002] Interferometry is characterized by high precision, non-contact operation, and fast response speed. It is widely used in the fields of component surface shape and transmitted wavefront detection, and provides important support for the processing of high-precision optical components. Currently, the basic structures for interferometry include Fizeau, Thyman Green, and Mach-Zehnder structures.

[0003] Currently, full-field heterodyne phase-shifting technology is widely used in interferometric measurement fields such as surface shape and transmitted wavefront. When applied to Fizeau interferometers, it mainly employs short coherence technology, which involves complex optical path matching and limited applicability. It cannot be used for direct measurement of aspherical components or components with large curvature radii and large apertures. When applied to Thyman Green and Mach-Zehnder structures, it suffers from parasitic waves and crosstalk introduced by parallel optical paths and parallel plates, which affect measurement accuracy and repeatability. The presence of a reference mirror in the structure introduces the influence of the reference mirror surface shape, affecting measurement accuracy. In absolute measurements, the solution is limited. Summary of the Invention

[0004] The purpose of this invention is to provide a dynamic interferometric measurement device based on a double-prism interferometer configuration. This device can be adapted to various light sources such as narrow linewidth light sources and short coherence light sources, taking into account the advantages of both types of light sources. At the same time, it has no influence on the accuracy of the measurement results due to the shape of the reference mirror. The surface shape of each component can be directly calibrated by the interferometric method, making it highly applicable in absolute measurements.

[0005] The objective of this invention is achieved through the following technical solution:

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

[0007] A narrow-linewidth dual-frequency heterodyne light source generates two beams. One beam is coupled into a first single-mode polarization-maintaining fiber as a reference beam, and is reflected by a first beam splitter to reach an imaging mirror. The output end of the first single-mode polarization-maintaining fiber is located at the mirror image of the focal point of the imaging mirror relative to the beam splitting surface of the first beam splitter, so that the reference beam reaching the detector is collimated.

[0008] Another light beam generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization maintaining optical fiber as the measurement light, and is reflected by the second light splitting prism to reach the standard mirror; the exit end surface of the second single-mode polarization maintaining optical fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflecting surface of the second light splitting prism, so as to ensure the effective F number of the standard mirror;

[0009] The standard mirror emits a high-quality spherical wave, which reaches the to-be-measured mirror, returns to the standard mirror and the second light splitting prism through the to-be-measured mirror in the original path; the transmitted light beam through the second light splitting prism converges first and then diverges, reaches the first light splitting prism, and then reaches the imaging mirror after being transmitted through the first light splitting prism, and reaches the detector after being collimated through the imaging mirror; the position of the converging point is located 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 the elements are calibrated by the interference measurement method.

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

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

[0013] Another light beam generated by the narrow linewidth dual-frequency heterodyne light source is coupled into the second single-mode polarization maintaining optical fiber as the measurement light, and is reflected by the second light splitting prism to reach the standard mirror; the exit end surface of the second single-mode polarization maintaining optical fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflecting surface of the second light splitting prism, so as to ensure the effective F number of the standard mirror;

[0014] The standard mirror emits a high-quality spherical wave, which reaches the to-be-measured mirror, returns to the standard mirror and the second light splitting prism through the to-be-measured mirror in the original path; the transmitted light beam through the second light splitting prism converges first and then diverges, reaches the first light splitting prism, and then reaches the imaging mirror after being transmitted through the first light splitting prism, and reaches the detector after being collimated through the imaging mirror; the position of the converging point is located at the focal point of the imaging mirror, so that the measurement light reaching the detector is collimated light;

[0015] The device further comprises a quarter-wave plate and a polarizer; the polarization state of the measurement light is matched from S polarization state to P polarization state by the light splitting prism cooperating with the quarter-wave plate, so as to improve the energy utilization rate; and the interference of the measurement light and the reference light is completed by cooperating with the polarizer.

[0016] The reference light is emitted from a first single-mode polarization maintaining optical fiber, reflected by a first light splitting prism, passes through a polarizer and an imaging lens, and reaches a detector;

[0017] The measurement light is emitted from a second single-mode polarization maintaining optical fiber, reflected by a second light splitting prism, passes through a quarter-wave plate and a standard mirror, and reaches a mirror to be measured; the light is reflected by the mirror to be measured, passes through the standard mirror and the quarter-wave plate again, and the polarization state is converted into a P polarization state; then the light is transmitted through the second light splitting prism, the first light splitting prism, and the polarizer, the polarization state is converted into a state consistent with the reference light, and then the light passes through the imaging lens, reaches the detector, and interferes with the reference light at the detector, and the surface shape of each element is calibrated by the interference measurement method.

[0018] As can be seen from the technical solutions provided by the above-mentioned application, the above-mentioned device can adapt to various light sources such as narrow linewidth light sources and short coherence light sources, take into account the advantages of the two kinds of light sources, and has no influence of the reference mirror surface shape on the measurement result accuracy, and can directly calibrate the surface shape of each element by the interference method, and has strong applicability in absolute measurement. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A structure schematic diagram of the dynamic interference measurement device based on the double-prism interferometer configuration according to the embodiment of the present application is shown in the figure.

[0021] Figure 2 An internal structure schematic diagram of the narrow linewidth double-frequency heterodyne light source according to the embodiment of the present application is shown in the figure.

[0022] Figure 3 A device structure schematic diagram of the device using cascaded prism replacement according to the embodiment of the present application is shown in the figure.

[0023] Figure 4 Another device structure schematic diagram of the device using cascaded prism replacement according to the embodiment of the present application is shown in the figure.

[0024] Figure 5 Another structure schematic diagram of the device according to the embodiment of the present application is shown in the figure.

[0025] Figure 6 A device structure schematic diagram when the mirror to be measured is a plane element according to the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0026] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments of the present application, which do not constitute a limitation to the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] As Figure 1 shown is a structural schematic diagram of a dynamic interference measurement device based on a double-prism interferometer configuration provided by an embodiment of the present application, the device comprising a narrow-line-width double-frequency heterodyne light source 1, a first single-mode polarization-maintaining optical fiber 2, a first light-splitting prism 3, an imaging mirror 4, a detector 5, a second single-mode polarization-maintaining optical fiber 6, a second light-splitting prism 7, and a standard mirror 8, wherein:

[0028] The narrow-line-width double-frequency heterodyne light source 1 generates two light beams, one of which is coupled into the first single-mode polarization-maintaining optical fiber 2 as reference light, and reaches the imaging mirror 4 after being reflected by the first light-splitting prism 3; the exit end of the first single-mode polarization-maintaining optical fiber 2 is located at the mirror image position of the focal point of the imaging mirror 4 relative to the light-splitting surface of the first light-splitting prism 3, so that the reference light reaching the detector 5 is collimated light;

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

[0030] The standard mirror 8 emits a high-quality spherical wave, which reaches the to-be-measured mirror 9, returns to the standard mirror 8 and the second light-splitting prism 7 via the to-be-measured mirror 9, and then reaches the detector 5 after being transmitted by the first light-splitting prism 3 and collimated by the imaging mirror 4; the position of the converging point is located at the focal point 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 generate interference at the detector 5, and the surface shapes of the elements, including the first light-splitting prism 3, the second light-splitting prism 7, and the imaging mirror 4 and the to-be-measured mirror 9, are calibrated by the interference measurement method.

[0032] As Figure 2 shown is a schematic diagram of the internal structure of the narrow-line-width double-frequency heterodyne light source, the narrow-line-width double-frequency heterodyne light source 1 comprising a laser 10, a polarization-maintaining 1-to-2 optical fiber 11, a cascaded acousto-optic frequency shifter 12, and an electrically adjustable optical fiber attenuation piece 13, wherein:

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

[0034] The cascaded acousto-optic frequency shifter 12 is packaged by cascading two acousto-optic frequency shifters, and the difference frequency light is generated after frequency shifting, with a frequency of several Hz to several hundred Hz. The light beam after frequency shifting is coupled into the second single-mode polarization maintaining optical fiber 6 to form the measurement light.

[0035] The electrically adjustable optical fiber attenuator 13 can adjust the light intensity of the light path to match the other path through an electrical signal, so as to ensure the contrast of the interference fringes. The light emitted by the electrically adjustable optical fiber attenuator 13 is coupled into the first single-mode polarization maintaining optical fiber 2 to form the reference light.

[0036] In a specific implementation, the measurement light and the reference light generate interference at the detector 5, and the signal relationship of the two light beams on the detector 5 is represented as:

[0037]

[0038] wherein I1 is the background light intensity; I2 is the modulated light intensity; v is the difference frequency; and t is the sampling time. is the phase information introduced by the surface shape of the image surface (x, y) of the to-be-measured mirror 9.

[0039] The sampling frame frequency of the detector 5 is set to match the difference frequency to complete the measurement image acquisition of N+1 steps of phase shifting, as shown in the following formula:

[0040]

[0041] wherein 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; and t i is the sampling time of the i-th step of phase shifting of the detector 5.

[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 use N-step phase shifting and other various phase calculation methods.

[0045] The above narrow linewidth double-frequency heterodyne light source 1 can be replaced by a short coherence double-frequency heterodyne light source. In addition to the heterodyne phase shifting method, mechanical phase shifting, wavelength phase shifting, polarization phase shifting, and other methods can also be used. The heterodyne phase shifting can also use an electro-optic phase shifting method.

[0046] Furthermore, in specific implementations, the first beam splitter 3 and the second beam splitter 7 can be replaced by a cascaded prism. This cascaded prism achieves beam convergence and divergence, such as... Figure 3 The diagram shown is a schematic representation of the device structure using cascaded prism replacement as described in an embodiment of the present invention. Figure 3 middle:

[0047] Compared to the separate prism scheme, although it is more difficult to calibrate the transmission wavefront error of the prism branch in the optical path using cascaded prisms, cascaded prisms have advantages in controlling the manufacturing error. The instrument system error can be directly reduced through precision manufacturing, thereby improving the basic measurement accuracy of the instrument. At the same time, cascaded prisms do not require control of the relative positions between prisms, making assembly and adjustment simpler.

[0048] Figure 3 The two beams entering the cascade prism are both incident from bottom to top below the cascade prism, which makes it easier to control the consistency of the two beams' incident points. However, the beam splitting surfaces of the cascade prism are not aligned, and the processing accuracy is not as high as when the beam splitting surfaces are aligned.

[0049] like Figure 4 The diagram shown is a schematic diagram of another device structure using cascaded prism replacement as described in an embodiment of the present invention. Figure 4 In the middle: Using another cascaded prism structure also has the advantages of cascaded prisms over separate prism schemes. Figure 4 The cascaded prisms have the same beam-splitting surfaces, which gives them an advantage in terms of processing precision. However, the two beams entering the cascaded prism have incident points 2 and 6 at the top and bottom ends of the cascaded prism, respectively, making it relatively difficult to control the consistency of the two beams.

[0050] In addition, such as Figure 5 The diagram shown is another structural schematic of the device described in an embodiment of the present invention. The device may further include a quarter-wave plate 14 and a polarizer 15. By using a beam splitter in conjunction with the quarter-wave plate 14 to match the polarization state of the measured light, the polarization state is converted from S-polarization to P-polarization, improving energy utilization. The polarizer 15, in conjunction with the measuring light, completes the interference between the measuring light and the reference light. Figure 5 :

[0051] The reference light is emitted from the first single-mode polarization-maintaining fiber 2, reflected by the first beam splitter prism 3, and passes through the polarizer 15 and the imaging mirror 4 to reach the detector 5.

[0052] The measuring light is emitted from the second single-mode polarization maintaining optical fiber 6, reflected by the second beam splitter prism 7, passes through the quarter-wave plate 14 and the standard mirror 8, and reaches the mirror to be measured 9; the measuring light is reflected by the mirror to be measured 9, passes through the standard mirror 8 and the quarter-wave plate 14 again, and the polarization state is converted into a P polarization state; then the measuring light is transmitted through the second beam splitter prism 7 and the first beam splitter prism 3, and the polarization state is converted into a polarization state consistent with the reference light by the polarizer 15; then the measuring light reaches the detector 5 through the imaging lens 4, and interference is generated with the reference light at the detector 5.

[0053] In specific implementation, the mirror to be measured 9 can be a spherical element or a planar element, and the corresponding standard mirror 8 is replaced according to the type of the mirror to be measured 9, for example, as shown in FIG. 4. Figure 6 FIG. 5 shows a device structure diagram when the mirror to be measured is a planar element according to the embodiment of the present application, and the measurement of the planar element is realized by replacing the standard mirror 8.

[0054] The embodiment of the present application also provides another dynamic interference measurement device based on a double-prism interferometer configuration, as shown in FIG. 6. Figure 5 The device includes a narrow-line-width double-frequency heterodyne light source, a first single-mode polarization maintaining optical fiber, a first beam splitter prism, an imaging lens, a detector, a second single-mode polarization maintaining optical fiber, a second beam splitter prism, and a standard mirror, wherein:

[0055] The narrow-line-width double-frequency heterodyne light source generates two light beams, one of which is coupled into the first single-mode polarization maintaining optical fiber as reference light, and the reference light reaches the imaging lens after being reflected by the first beam splitter prism; the exit end of the first single-mode polarization maintaining optical fiber is located at the mirror image position of the focal point 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 light beam generated by the narrow-line-width double-frequency heterodyne light source is coupled into the second single-mode polarization maintaining optical fiber as measuring light, and the measuring light reaches the standard mirror after being reflected by the second beam splitter prism; the exit end surface of the second single-mode polarization maintaining optical fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflecting surface of the second beam splitter prism, so as to ensure the effective F number of the standard mirror;

[0057] The standard mirror emits a high-quality spherical wave, the spherical wave reaches the mirror to be measured, and the spherical wave returns to the standard mirror and the second beam splitter prism through the mirror to be measured; the transmitted light beam through the second beam splitter prism converges first and then diverges, reaches the first beam splitter prism, and reaches the imaging lens after being transmitted through the first beam splitter prism, and reaches the detector after being collimated by the imaging lens, and the converging point is located at the focal point of the imaging lens, so that the measuring light reaching the detector is collimated light;

[0058] As shown in FIG. 7, the device further includes a quarter-wave plate and a polarizer, the polarization state of the measuring light is converted from an S polarization state to a P polarization state by the cooperation of the beam splitter prism and the quarter-wave plate, the energy utilization rate is improved, and the interference of the measuring light and the reference light is completed by the cooperation of the polarizer, wherein: Figure 5 ​

[0059] The reference light is emitted by the first single-mode polarization maintaining optical fiber, reflected by the first light splitting prism, transmitted through the polarizer and the imaging lens, and reaches the detector;

[0060] The measurement light is emitted by the second single-mode polarization maintaining optical fiber, reflected by the second light splitting prism, transmitted through the quarter-wave plate and the standard mirror, and reaches the to-be-measured mirror; the measurement light is reflected by the to-be-measured mirror, transmitted through the standard mirror and the quarter-wave plate again, and the polarization state is converted into a P polarization state; then the measurement light is transmitted through the second light splitting prism, the first light splitting prism, and the polarizer, and the polarization state is converted into a polarization state consistent with the reference light; then the measurement light is transmitted through the imaging lens, reaches the detector, and interferes with the reference light at the detector, and the surface shape of each element is calibrated by the interference measurement method.

[0061] It is worth noting that the contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art.

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

[0063] 1. The structure of the present application can adapt to narrow line width light sources, short coherence light sources and other light sources. Using a short coherence light source can eliminate the influence of other light beams on the measurement results, and using a narrow line width light source can improve the coherence length, adapt to the measurement of large optical path range measured members and long focal large aperture elements;

[0064] 2. The present application mainly uses a divergent light path to further suppress the influence of parasitic waves on the measurement results, and avoids the influence of mixing frequency crosstalk on the measurement results in principle;

[0065] 3. The present application uses a high-quality spherical wave generated by fiber direct emission or point diffraction as the emitted reference, which avoids the influence of the reference mirror surface on the measurement result precision;

[0066] 4. The machining precision of the control prism or the cascaded prism in the present application can achieve high measurement precision, and reduce system error;

[0067] 5. The present application can directly calibrate the surface shape of each element in the construction process by using the high-quality spherical wave generated by fiber direct emission or point diffraction interference, which has strong applicability in absolute measurement.

[0068] The above description is merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions easily conceived by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is merely intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known to those skilled in the art.

Claims

1. A dynamic interferometry apparatus based on a two-prism interferometer configuration, characterized in that, The device comprises a narrow linewidth double-frequency heterodyne light source, a first single-mode polarization maintaining optical fiber, a first light splitting prism, an imaging mirror, a detector, a second single-mode polarization maintaining optical fiber, a second light splitting prism, and a standard mirror, wherein: The narrow linewidth double-frequency heterodyne light source generates two light beams, one of which is coupled into the first single-mode polarization maintaining optical fiber as reference light and reaches the imaging mirror after being reflected by the first light splitting prism; the exit end of the first single-mode polarization maintaining optical fiber is located at the mirror image position of the focal point of the imaging mirror relative to the light splitting surface of the first light splitting prism, so that the reference light reaching the detector is collimated light; The other light beam generated by the narrow linewidth double-frequency heterodyne light source is coupled into the second single-mode polarization maintaining optical fiber as measurement light and reaches the standard mirror after being reflected by the second light splitting prism; the exit end of the second single-mode polarization maintaining optical fiber is located at the mirror image position of the designed incident point of the standard mirror relative to the reflecting surface of the second light splitting prism, so as to ensure the effective F number of the standard mirror; The standard mirror emits high-quality spherical waves, which reach the mirror to be measured, return to the standard mirror and the second light splitting prism through the mirror to be measured in the original path; the transmitted light beam through the second light splitting prism converges first and then diverges, reaches the first light splitting prism, and reaches the imaging mirror after being transmitted through the first light splitting prism and collimated through the imaging mirror, and reaches the detector; the converging point is located at the focal point of the imaging mirror, so that the measurement light reaching the detector is collimated light; The measurement light and the reference light interfere at the detector, and the surface shape of each element is calibrated by the interference measurement method.

2. The dynamic interferometry apparatus based on a two-prism interferometer configuration of claim 1, wherein, The narrow linewidth double-frequency heterodyne light source comprises a laser, a polarization maintaining 1:2 optical fiber, a cascaded acousto-optic frequency shifter, and an electrically adjustable optical fiber attenuator, wherein: The laser emits a narrow linewidth light beam, which is split into two paths after passing through the polarization maintaining 1:2 optical fiber, one of which passes through the cascaded acousto-optic frequency shifter, and the other of which passes through the electrically adjustable optical fiber attenuator; The cascaded acousto-optic frequency shifter is packaged by cascading two acousto-optic frequency shifters, generates difference frequency light after frequency shifting, and the frequency is several Hz to several hundred Hz; the light beam after frequency shifting is coupled into the second single-mode polarization maintaining optical fiber to form measurement light; The electrically adjustable optical fiber attenuator can adjust the light intensity of the light beam to match the other light beam through an electrical signal, so as to ensure the contrast of the interference fringes; the exit light of the electrically adjustable optical fiber attenuator is coupled into the first single-mode polarization maintaining optical fiber to form reference light.

3. The dynamic interferometry apparatus based on a two-prism interferometer configuration of claim 1, wherein, The measurement light and the reference light interfere at the detector, and the signal relationship of the two light beams on the detector is represented as: Wherein, I1 is background light intensity; I2 is modulation light intensity; v is the difference frequency; t is the sampling time; is the phase information introduced by the surface shape of the image (x, y) of the mirror to be tested; The sampling frame frequency of the detector is set to match the difference frequency to complete the measurement image acquisition of N+1 phase shifting, as shown in the following formula: where N is the number of phase-shifting steps; I(x, y, t i ) is the interference light intensity of the i-th phase-shifting step collected by the detector; t i is the sampling time of the i-th phase-shifting step corresponding to the detector; solved phase information As shown in the following equation:

4. The dynamic interferometry apparatus based on a two-prism interferometer configuration of claim 1, wherein, The first light splitting prism and the second light splitting prism can be replaced by a cascaded prism to realize the convergence and divergence of the light beams through the cascaded prism; The two light beams entering the cascaded prism are incident from below to above. Alternatively, the two light beams entering the cascaded prism are incident at the upper and lower ends of the cascaded prism, respectively.

5. The dynamic interferometry apparatus based on a two-prism interferometer configuration of claim 1, wherein, The device further comprises a quarter-wave plate and a polarizer; the polarization state of the measurement light is matched from S polarization state to P polarization state by the light splitting prism cooperating with the quarter-wave plate, the energy utilization rate is improved, and the interference of the measurement light and the reference light is completed by the polarizer, wherein: The reference light is emitted from the first single-mode polarization maintaining optical fiber, reflected by the first light splitting prism, passes through the polarizer and the imaging mirror, and reaches the detector. The measurement light is emitted from the second single-mode polarization-maintaining fiber, reflected by the second beam splitter, and then passes through a quarter-wave plate and a standard mirror before reaching the mirror under test. It is then reflected back by the mirror under test, passes through the standard mirror and a quarter-wave plate again, and its polarization state is converted to P polarization. It is then transmitted through the second beam splitter and the first beam splitter, and its polarization state is converted to be consistent with the reference light by a polarizer. Finally, it passes through the imaging mirror and reaches the detector, where it interferes with the reference light at the detector.

6. The dynamic interferometric measurement device based on a double-prism interferometer configuration according to claim 1, characterized in that, The mirror under test is either a spherical element or a planar element, and the corresponding standard mirror is replaced according to the type of mirror under test.

7. A dynamic interferometry apparatus based on a two-prism interferometer configuration, characterized in that, 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, and a standard mirror, wherein: A narrow-linewidth dual-frequency heterodyne light source generates two beams. One beam is coupled into a first single-mode polarization-maintaining fiber as a reference beam, and is reflected by a first beam splitter to reach an imaging mirror. The output end of the first single-mode polarization-maintaining fiber is located at the mirror image of the focal point of the imaging mirror relative to the beam splitting surface of the first beam splitter, so that the reference beam reaching the detector is collimated. 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 is reflected by the second beam splitter 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 design incident point of the standard mirror relative to the reflective surface of the second beam splitter, ensuring the effective F number of the standard mirror. A high-quality spherical wave is emitted from the standard mirror. This spherical wave reaches the mirror under test and returns to the standard mirror and the second beam splitter through the mirror under test. The transmitted beam after passing through the second beam splitter converges and then diverges, reaching the first beam splitter. After being transmitted through the first beam splitter, it reaches the imaging mirror and is collimated by the imaging mirror before reaching the detector. The convergence point is located at the focal point of the imaging mirror, so that the measurement light reaching the detector is collimated. The device also includes a quarter-wave plate and a polarizer. By using a beam splitter in conjunction with the quarter-wave plate to match the measurement light polarization state from S-polarization to P-polarization, energy utilization is improved. Furthermore, the polarizer, in conjunction with the measurement light, enables interference between the reference light and the measurement light. The reference light is emitted from the first single-mode polarization-maintaining fiber, reflected by the first beam splitter, and then passes through the polarizer and imaging mirror to reach the detector. The measurement light is emitted from the second single-mode polarization-maintaining fiber, reflected by the second beam splitter, and then passes through a quarter-wave plate and a standard mirror before reaching the mirror under test. It is then reflected back by the mirror under test, passes through the standard mirror and a quarter-wave plate again, and its polarization state is converted to P polarization. It is then transmitted through the second beam splitter and the first beam splitter, and its polarization state is converted to be consistent with the reference light by a polarizer. Finally, it passes through the imaging mirror to reach the detector, where it interferes with the reference light. The surface shape of each component is calibrated by interferometry.

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