Quasi-monolithic high-precision five-degree-of-freedom interferometer

Abstract

The invention belongs to the technical field of precision measurement, and particularly discloses a quasi-monolithic high-precision five-degree-of-freedom interferometer. According to the invention, through the single-chip design, due to the exquisite optical path design, a plurality of optical elements are fully multiplexed, so that the number of the optical elements is reduced, and the integrity and robustness of the device are improved; according to the invention, the optical fiber collimator is bonded through epoxy resin to construct the integrated small collimator, and the K9 glass or the ultra-low expansion glass is adopted as the mounting substrate, and integrated bonding is carried out, so that the pointing stability can be improved, and the influence of environmental fluctuation is small; according to the invention, through a differential wavefront sensing technology, only two groups of measurement interferometers and one group of reference interferometers are adopted, common-mode rejection and other methods are utilized, measurement noise is effectively reduced, high-precision measurement of five degrees of freedom of biaxial displacement, a pitch angle, a yaw angle and a roll angle is realized, and picometer-level and nano-radian-level displacement measurement capability is realized.

Description

Technical Field

[0001] This application belongs to the field of precision measurement technology, and more specifically, relates to a quasi-monolithic high-precision five-degree-of-freedom interferometer. Background Technology

[0002] An object's spatial attitude is determined by six degrees of freedom, including position determined by three linear quantities and attitude determined by three angular quantities. High-precision measurement of multiple degrees of freedom (such as displacement and deflection) is one of the core requirements in fields such as precision manufacturing and aerospace. Traditional multi-degree-of-freedom measurement equipment typically adopts a multi-component discrete layout, which suffers from problems such as large size, complex assembly and adjustment, and high sensitivity to environmental interference. Existing interferometric multi-degree-of-freedom measurement devices either have limited measurement accuracy due to the complexity of the degree-of-freedom decoupling algorithm, or have difficulty balancing measurement resolution and system stability due to low structural integration.

[0003] To reduce the size of the optical path and enhance its stability and robustness, optical components can be fixed onto a unified optical substrate through bonding, welding, or other methods, which can be called a quasi-monolithic precision integrated optical path. Although the quasi-monolithic optical structure can improve the system integration, existing quasi-monolithic interferometers mostly focus on the measurement of 3 to 4 degrees of freedom, and cannot simultaneously achieve high-precision synchronous detection of five degrees of freedom (e.g., X / Y / Z linear displacement, angular deflection around the X / Y axis). Furthermore, the measurement stability under environmental vibration and temperature drift needs to be improved.

[0004] Therefore, there is an urgent need for a quasi-monolithic interferometer structure that is highly integrated, easy to assemble and adjust, and capable of high-precision synchronous measurement of five degrees of freedom, in order to meet the high performance requirements of multi-degree-of-freedom measurement in the field of precision engineering. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a quasi-monolithic high-precision five-degree-of-freedom interferometer, which aims to solve the problems that existing quasi-monolithic interferometers cannot simultaneously achieve high-precision synchronous detection of five degrees of freedom, and that measurement stability under environmental vibration and temperature drift needs to be improved.

[0006] To achieve the above objectives, this application provides a quasi-monolithic high-precision five-degree-of-freedom interferometer, comprising a laser emitting unit, an interference signal generating unit, and a five-degree-of-freedom solving unit arranged sequentially. The interference signal generation unit is communicatively connected to the five-degree-of-freedom solution unit and includes: a first fiber collimator, a second fiber collimator, a first to a sixth depolarizing beam splitter, a single-quadrant photodetector, a first four-quadrant photodetector, and a second four-quadrant photodetector. When the quasi-monolithic high-precision five-degree-of-freedom interferometer is working, the first laser beam emitted by the laser emitting unit is collimated by the first fiber collimator. One path is transmitted through the first depolarizing beam splitter to form the first transmitted light, and the other path is reflected by the first depolarizing beam splitter to form the first reflected light. Among them, when the first transmitted light passes through the second depolarizing beam splitter, one path is transmitted by it and reflected at the first plane of the cube to be measured. The reflected laser carries the displacement information of the reflecting surface and is reflected by the second depolarizing beam splitter to form the first measurement light. The other path is reflected by it, then reflected by the sixth depolarizing beam splitter and transmitted by the third depolarizing beam splitter to form the second reference light. The first reflected light is transmitted through the fifth depolarizing beam splitter to form the third measurement light. The second laser beam emitted by the laser emitting unit is collimated by the second fiber collimator. One path is transmitted through the third depolarizing beam splitter to form the second transmitted light, and the other path is reflected by the third depolarizing beam splitter to form the second reflected light. Among them, when the second transmitted light passes through the fourth depolarizing beam splitter, one path is transmitted by it and reflected at the second plane of the cube to be measured. The reflected laser carries the displacement information of the reflecting surface and is reflected by the fourth depolarizing beam splitter to form the second measurement light. The other path is reflected by it, then reflected by the sixth depolarizing beam splitter and transmitted by the second depolarizing beam splitter to form the first reference light. The second reflected light is reflected by the fifth depolarizing beam splitter to form the third reference light. The first plane and the second plane are perpendicular to each other. The first measuring light and the first reference light form a first set of interference signals on the first four-quadrant photodetector; the second measuring light and the second reference light form a second set of interference signals on the second four-quadrant photodetector; and the third measuring light and the third reference light form a third set of interference signals on the single-quadrant photodetector. The five-degree-of-freedom calculation unit is used to obtain the displacement changes of the two planes of the cube under test based on the first set of interference signals, the second set of interference signals, and the third set of interference signals, through phase calculation and noise suppression; and to obtain the pitch angle changes, yaw angle changes, and roll angle changes of the two planes of the cube under test based on the first set of interference signals and the second set of interference signals, through phase calculation and differential wavefront sensing calibration.

[0007] Preferably, the third set of interference signals is a reference interference signal used to monitor measurement noise caused by external factors; the first set of interference signals and the second set of interference signals are measurement interference signals, which are interference signals reflected by the two planes of the cube under test and contain three degrees of freedom information of each plane.

[0008] Preferably, the laser emitting unit is a narrow linewidth laser used to emit a laser beam to the first fiber collimator and the second fiber collimator.

[0009] Preferably, the device further includes a first glass mounting base and a second glass mounting base, wherein the glass mounting base has a central through hole to ensure that the first fiber collimator and the second fiber collimator can be placed at the center of the glass mounting base.

[0010] Preferably, it also includes a glass substrate, and all optical components in the interference signal generation unit are bonded to the glass substrate with UV adhesive.

[0011] Preferably, the quasi-monolithic high-precision five-degree-of-freedom interferometer has a symmetrical L-shaped configuration.

[0012] Preferably, the five-degree-of-freedom solving element obtains the displacement changes of the two planes using the following formula: ; ; in, This represents the axial displacement change of the first plane. This represents the axial displacement change in the second plane. These are the measured phase signals detected by the photodetector in the first and fourth quadrants, respectively. These are the measured phase signals detected by the photodetector in the second and fourth quadrants, respectively. This is the reference phase signal detected by a single-quadrant photodetector. This is the center wavelength of the laser.

[0013] Preferably, the five-degree-of-freedom solving unit obtains the pitch angle variation, yaw angle variation, and roll angle variation of the two planes using the following formulas: ; ; ; ; in, These represent the changes in pitch angle, yaw angle, and roll angle in the first plane, respectively. These represent the changes in pitch angle, yaw angle, and roll angle in the second plane, respectively. These are the measured phase signals detected by the photodetector in the first and fourth quadrants, respectively. These are the measured phase signals detected by the photodetector in the second and fourth quadrants, respectively. These are the pitch and yaw angle differential sensing coefficients of the first and second sets of interference signals, respectively.

[0014] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: First, given that existing five-degree-of-freedom measurement devices are generally large in size and have low integration, this application adopts a monolithic design. Due to the ingenious optical path design, multiple optical elements are fully reused, thereby reducing the number of optical elements and improving the device's integrity and robustness. It can be widely used in fields such as gravitational wave detection, inertial sensing, vibration meters, and seismometers.

[0015] Secondly, in view of the low pointing stability of existing commercial collimators, this application uses epoxy resin to bond fiber optic collimators to build an integrated small collimator. Since K9 glass or ultra-low expansion glass is used as the mounting base and integrated bonding is performed, pointing stability can be improved and it is less affected by environmental fluctuations.

[0016] Third, in view of the low accuracy of existing five-degree-of-freedom measurements, this application uses differential wavefront sensing technology, employing only two sets of measurement interferometers and one set of reference interferometers, and utilizes common-mode suppression and other methods to effectively reduce measurement noise, thereby achieving high-precision measurement of the five degrees of freedom of dual-axis displacement, pitch, yaw and roll, with displacement measurement capabilities at the picometer and nanoradian levels. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a quasi-monolithic high-precision five-degree-of-freedom interferometer provided in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of the interference signal generation unit provided in the embodiment of this application.

[0019] Figure 3 This is a displacement measurement sensitivity curve of the quasi-monochip high-precision five-degree-of-freedom interferometer provided in the embodiments of this application.

[0020] Figure 4 This is a graph showing the angle measurement sensitivity of the quasi-monolithic high-precision five-degree-of-freedom interferometer provided in the embodiments of this application.

[0021] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is a glass substrate, 2 is the cube to be measured, 3 is the first glass mounting base, 4 is the first fiber collimator, 5 is the second glass mounting base, 6 is the second fiber collimator, 7, 8, 9, 10, 11, 12 are the first to the sixth depolarizing beam splitters respectively, 13 is a single-quadrant photodetector, 14 is the first four-quadrant photodetector, and 15 is the second four-quadrant photodetector. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] The embodiments of this application are described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this application provides a quasi-monolithic high-precision five-degree-of-freedom interferometer, comprising: a laser emitting unit, an interference signal generating unit, and a five-degree-of-freedom solving unit arranged sequentially, wherein the interference signal generating unit and the five-degree-of-freedom solving unit are communicatively connected.

[0025] Preferably, the laser emitting unit is a narrow linewidth laser, used to emit a laser beam to the first fiber collimator 4 and the second fiber collimator 6.

[0026] like Figure 2 As shown, the interference signal generation unit includes: a first fiber collimator 4, a second fiber collimator 6, a first depolarizing beam splitter to a sixth polarizing beam splitter 7-12, a single-quadrant photodetector 13, a first four-quadrant photodetector 14, and a second four-quadrant photodetector 15; wherein, When the quasi-monolithic high-precision five-degree-of-freedom interferometer is working, the first laser beam emitted by the laser emitting unit is collimated by the first fiber collimator 4. One path is transmitted through the first depolarizing beam splitter 7 to form the first transmitted light, and the other path is reflected by the first depolarizing beam splitter 7 to form the first reflected light. Among them, when the first transmitted light passes through the second depolarizing beam splitter 8, one path is transmitted by it and reflected at the first plane of the cube 2 to be measured. The reflected laser carries the displacement information of the reflecting surface and is reflected by the second depolarizing beam splitter 8 to form the first measurement light. The other path is reflected by it and then reflected by the sixth depolarizing beam splitter 12 and transmitted by the third depolarizing beam splitter 10 to form the second reference light. The first reflected light is transmitted through the fifth depolarizing beam splitter 11 to form the third measurement light. After the second laser beam emitted by the laser emitting unit is collimated by the second fiber collimator (6), one path is transmitted through the third depolarizing beam splitter 9 to form the second transmitted light, and the other path is reflected by the third depolarizing beam splitter 9 to form the second reflected light. Among them, when the second transmitted light passes through the fourth depolarizing beam splitter 10, one path is transmitted by it and reflected at the second plane of the cube 2 to be measured. The reflected laser carries the displacement information of the reflecting surface and is reflected by the fourth depolarizing beam splitter 10 to form the second measurement light. The other path is reflected by it and then reflected by the sixth depolarizing beam splitter 12 and transmitted by the second depolarizing beam splitter 8 to form the first reference light. The second reflected light is reflected by the fifth depolarizing beam splitter 11 to form the third reference light. The first plane and the second plane are perpendicular to each other. The first measuring light and the first reference light form a first set of interference signals on the first four-quadrant photodetector 14, the second measuring light and the second reference light form a second set of interference signals on the second four-quadrant photodetector 15, and the third measuring light and the third reference light form a third set of interference signals on the single-quadrant photodetector 13.

[0027] Preferably, the third set of interference signals is a reference interference signal used to monitor measurement noise caused by external factors such as the environment and the front-end link; the first set of interference signals and the second set of interference signals are measurement interference signals, which are interference signals reflected by two mutually perpendicular planes of the cube under test, and contain three degrees of freedom information of their respective planes.

[0028] The five-degree-of-freedom calculation unit is used to directly calculate the displacement changes of two mutually perpendicular planes based on the first, second, and third sets of interference signals via a phase meter; and to obtain the pitch angle, yaw angle, and roll angle changes of the two planes of the cube under test based on the first and second sets of interference signals via phase meter calculation and differential wavefront sensor calibration. Preferably, the laser collimator pigtail is made of polarization-maintaining fiber to avoid changes in the laser polarization direction caused by factors such as fiber bending or stress.

[0029] Preferably, the depolarization beam splitter is of the depolarization type, which can avoid affecting the laser polarization and thus change the 50:50 beam splitting ratio.

[0030] Preferably, the five-degree-of-freedom interferometer further includes a first glass mounting base 3 and a second glass mounting base 5, wherein the glass mounting base has a central perforation to ensure that the first fiber collimator 4 and the second fiber collimator 6 can be placed at the center of the glass mounting base.

[0031] Preferably, the five-degree-of-freedom interferometer further includes a glass substrate 1, and all optical components in the interference signal generation unit are bonded to the glass substrate 1 with ultraviolet adhesive, which can enhance the robustness and integrity of the device.

[0032] Preferably, the five-degree-of-freedom solving unit obtains the displacement changes in two mutually perpendicular planes using the following formula: ; ; in, The axial displacement change of the first plane of the cube under test. The first and second planes represent the axial displacement of the second plane of the cube under test. The first and second planes are two mutually perpendicular faces of the cube under test. These are the measured phase signals detected by the first four-quadrant photodetector 14. These are the measured phase signals detected by the second-fourth quadrant photodetector 15. This is the reference phase signal detected by the single-quadrant photodetector 13. This is the center wavelength of the laser.

[0033] Preferably, the five-degree-of-freedom solving unit obtains the pitch angle and yaw angle changes of the two planes using the following formulas: ; ; ; ;in, These represent the changes in pitch and yaw angles of the first plane of the cube under test. These represent the pitch and yaw angle changes of the second plane of the cube under test, respectively. The first and second planes are two mutually perpendicular faces of the cube under test. These are the pitch and yaw angle differential sensing coefficients for the first and second sets of interferometric signals, respectively. Since the first and second planes are perpendicular, the pitch angle of the second plane... The change corresponds to the change in the roll angle of the first plane. The pitch angle of the first plane The change corresponds to the change in the roll angle of the second plane. And the yaw angle changes between the first plane and the second plane Same. Differential wavefront sensing coefficients Angle modulation experiments can be conducted using devices such as autocollimators for calibration.

[0034] Example In this embodiment, the glass base has dimensions of 200*200*10 mm, is made of K9 glass, and has a polished and flat surface for easy placement of optical components. The cube to be tested has dimensions of 80*80*80 mm, is made of aluminum alloy, and has a polished and flat surface to meet the requirements of laser reflection. The glass mounting base has dimensions of 10*10*10 mm, is made of K9 glass, and has a through-hole with a diameter of 3 mm at its center to facilitate adjustment of the fiber optic collimator's orientation and fix it to the glass mounting base as a whole. The fiber optic collimator is cylindrical, with a diameter of 3 mm, a length of 9 mm, a pigtail length of 1 m, and uses polarization-maintaining fiber with a design wavelength of 1064 nm. Its output beam waist is a fundamental mode Gaussian beam. The depolarizing beam splitter has dimensions of 10*10*10 mm, a reflectivity of 50:50, a design wavelength of 1064 nm, and is insensitive to polarization to avoid changes in the beam polarization causing changes in the splitting ratio. The single-quadrant photodetector has an effective detection area of ​​a circular region with a diameter of 3.6 mm, uses Si as the photoelectric material, has a detection wavelength of 350-1100 nm, and a detection bandwidth of 12 MHz, which meets the requirements for heterodyne detection. The four-quadrant photodetector 7 has an effective detection area of ​​a circular region with a diameter of 3 mm, uses InGaAs as the photoelectric material, has a detection wavelength of 1000-1700 nm, and a detection bandwidth of 150 kHz, which also meets the requirements for heterodyne detection.

[0035] The above optical components are then positioned and cured using UV adhesive, specifically including the following steps: Step 1: Place the fiber optic collimator at the center perforation of the glass mounting base. Using the optical platform as a reference, adjust the laser emitted from the fiber optic collimator to be parallel to the optical platform. Then, use UV adhesive to cure the two together to form a whole.

[0036] Step 2: Fix the glass substrate onto the optical platform, keeping it parallel to the platform. Then, place the entire assembly of the two glass mounts and the fiber collimator onto the glass substrate. The heterodyne frequency of the two laser beams emitted from the fiber collimator is 10 kHz. Adjust the two glass mounts so that the two laser beams are parallel to the optical platform, thus forming two heterodyne beams. Finally, solidify the two glass mounts to the glass substrate.

[0037] Step 3: Place the cube to be tested in the gap of the glass substrate and fix it on the optical platform. At this time, the two laser beams emitted from the fiber collimator need to be reflected back into the fiber collimator along the original path. A circulator can be used to monitor the optical power of the returned light to determine whether the laser beams reflected by the plane mirror return along the original path.

[0038] Step 4: Place the three depolarizing beam splitters at appropriate positions on the glass substrate according to the optical path design, serving to split and combine the two interfering laser beams. This will generate an interference signal. Adjust the position and orientation of the three depolarizing beam splitters to maximize the contrast of the interference beams. Then, sequentially solidify the three beam splitters onto the glass substrate. The contrast of the interference beams can be monitored using a single-quadrant photodetector.

[0039] Step 5: Place the remaining three depolarizing beam splitters at appropriate positions on the glass substrate according to the optical path design, serving to split and combine the two interfering laser beams. This will generate two sets of interference signals. Measure two faces of the cube respectively. Adjust the position and orientation of the three depolarizing beam splitters to maximize the contrast of the interference beams. Then, solidify the three beam splitters and the glass substrate sequentially. The contrast of the interference beams can be monitored using a four-quadrant photodetector.

[0040] The displacement measurement sensitivity of a single-chip high-precision five-degree-of-freedom interferometer is as follows: Figure 3 As shown, in the frequency band above 1Hz, the displacement measurement sensitivity is better than It reaches the picometer level. The angle measurement sensitivity of a single-chip high-precision five-degree-of-freedom interferometer is as follows: Figure 4 As shown, in the frequency band above 1Hz, the angle measurement sensitivity is better than It reaches the sub-nanometer level.

[0041] In this application, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0042] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0043] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0044] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0045] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0046] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0047] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0048] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A quasi-monolithic high-precision five-degree-of-freedom interferometer, characterized in that, It includes a laser emitting unit, an interference signal generating unit, and a five-degree-of-freedom solution unit arranged sequentially; The interference signal generation unit is communicatively connected to the five-degree-of-freedom solution unit and includes: a first fiber collimator (4), a second fiber collimator (6), a first depolarization beam splitter to a sixth depolarization beam splitter (7,8,9,10,11,12), a single-quadrant photodetector (13), a first four-quadrant photodetector (14), and a second four-quadrant photodetector (15). When the quasi-monolithic high-precision five-degree-of-freedom interferometer is working, the first laser beam emitted by the laser emitting unit is collimated by the first fiber collimator (4), and one path is transmitted through the first depolarization beam splitter (7) to form the first transmitted light, and the other path is reflected by the first depolarization beam splitter (7) to form the first reflected light; among them, when the first transmitted light passes through the second depolarization beam splitter (8), one path is transmitted by it and reflected at the first plane of the cube to be measured (2). The reflected laser carries the displacement information of the reflecting surface and is reflected by the second depolarization beam splitter (8) to form the first measurement light. The other path is reflected by it and then reflected by the sixth depolarization beam splitter (12) and transmitted by the third depolarization beam splitter (10) to form the second reference light. The first reflected light is transmitted through the fifth depolarization beam splitter (11) to form the third measurement light. After the second laser beam emitted by the laser emitting unit is collimated by the second fiber collimator (6), one path is transmitted through the third depolarizing beam splitter (9) to form the second transmitted light, and the other path is reflected by the third depolarizing beam splitter (9) to form the second reflected light. Among them, when the second transmitted light passes through the fourth depolarizing beam splitter (10), one path is transmitted by it and reflected at the second plane of the cube to be measured (2). The reflected laser carries the displacement information of the reflecting surface and is reflected by the fourth depolarizing beam splitter (10) to form the second measurement light. The other path is reflected by it and then reflected by the sixth depolarizing beam splitter (12) and transmitted by the second depolarizing beam splitter (8) to form the first reference light. The second reflected light is reflected by the fifth depolarizing beam splitter (11) to form the third reference light. The first plane and the second plane are perpendicular to each other. The first measuring light and the first reference light form a first set of interference signals on the first four-quadrant photodetector (14), the second measuring light and the second reference light form a second set of interference signals on the second four-quadrant photodetector (15), and the third measuring light and the third reference light form a third set of interference signals on the single-quadrant photodetector (13). The five-degree-of-freedom solution unit is used to obtain the displacement changes of the two planes of the cube under test (2) by phase calculation and noise suppression based on the first set of interference signals, the second set of interference signals and the third set of interference signals; and to obtain the pitch angle change, yaw angle change and roll angle change of the two planes of the cube under test (2) by phase calculation and differential wavefront sensing calibration based on the first set of interference signals and the second set of interference signals.

2. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, The third set of interference signals is a reference interference signal used to monitor measurement noise caused by external factors; the first and second sets of interference signals are measurement interference signals, which are interference signals reflected by the two planes of the cube under test and contain three degrees of freedom information of each plane.

3. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, The laser emitting unit is a narrow linewidth laser used to emit laser beams to the first fiber collimator and the second fiber collimator.

4. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, It also includes a first glass mounting base (3) and a second glass mounting base (5), wherein the glass mounting base has a central perforation to ensure that the first fiber collimator (4) and the second fiber collimator (6) can be placed at the center of the glass mounting base.

5. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, It also includes a glass substrate (1), and all optical components in the interference signal generation unit are bonded to the glass substrate (1) with UV adhesive.

6. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, The quasi-monolithic high-precision five-degree-of-freedom interferometer has a symmetrical L-shaped configuration.

7. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, The displacement changes of the two planes are obtained using the following formula for the five-degree-of-freedom solution element: ； ； in, This represents the axial displacement change of the first plane. This represents the axial displacement change in the second plane. These are the measured phase signals detected by the photodetector in the first and fourth quadrants, respectively. These are the measured phase signals detected by the photodetector in the second and fourth quadrants, respectively. This is the reference phase signal detected by a single-quadrant photodetector. The wavelength is the center wavelength of the laser.

8. The quasi-monolithic high-precision five-degree-of-freedom interferometer as described in claim 1, characterized in that, The five-degree-of-freedom solving element obtains the pitch angle, yaw angle, and roll angle changes in the two planes using the following formulas: ； ； ； ； in, These represent the changes in pitch angle, yaw angle, and roll angle in the first plane, respectively. These represent the changes in pitch angle, yaw angle, and roll angle in the second plane, respectively. These are the measured phase signals detected by the photodetector in the first and fourth quadrants, respectively. These are the measured phase signals detected by the photodetector in the second and fourth quadrants, respectively. These are the pitch and yaw angle differential sensing coefficients of the first and second sets of interference signals, respectively.

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