A multi-degree-of-freedom adjustable laser interference alignment device

Abstract

This invention relates to the field of optical inspection and optical path alignment, and discloses a multi-degree-of-freedom adjustable laser interferometric alignment device, comprising a frame, a main optical path channel fixedly installed on one side of the frame, a polarizing beam splitter fixedly installed in the middle of the main optical path channel with an installation tilt angle of 45°, a fixed waveplate fixedly installed inside the main optical path channel near the lower part of the polarizing beam splitter, a polarization state sensor fixedly installed inside the main optical path channel between the polarizing beam splitter and the fixed waveplate, and a beam splitter mirror fixedly installed on the lower side of the main optical path channel with an installation tilt angle of 45°. This invention achieves precise multi-degree-of-freedom adjustment and sub-micron level alignment accuracy, is highly adaptable to various environments, and is easy to operate. It effectively solves the problems of single alignment dimension and insufficient accuracy in traditional devices, and is suitable for high-end scenarios such as high-power laser communication.

Description

Technical Field

[0001] This invention relates to the field of optical inspection and optical path alignment, specifically to a multi-degree-of-freedom adjustable laser interferometric alignment device. Background Technology

[0002] In high-end optical applications such as ultra-wide field-of-view acquisition in high-power laser communication and long-distance transmission detection in laser fusion, the accuracy of optical path alignment directly determines the upper limit of system performance. As these fields develop towards higher power, longer distances, and wider fields of view, stringent requirements are placed on optical path alignment: not only must sub-micron level alignment accuracy be achieved, but also multi-dimensional errors such as optical axis misalignment, tilt deviation, and torsional deviation must be addressed, while also adapting to long-term stable operation in complex environments. For example, ultra-wide field-of-view acquisition in laser communication requires rapid locking of the target optical path, and laser fusion transmission detection needs to overcome alignment deviations caused by long-distance optical path differences. These scenarios urgently require multi-degree-of-freedom, high-precision alignment solutions.

[0003] However, existing laser interferometry devices have significant limitations in optical path alignment. Traditional optical axis alignment technology relies on a single photodetector, which can only identify deviations in a limited number of dimensions. Its insufficient resolution makes spot alignment difficult, and alignment accuracy is mostly limited to the micrometer level, failing to meet the needs of sub-micrometer applications. Most devices only support single or a few degrees of freedom adjustment, making it difficult to simultaneously correct multi-dimensional errors such as translation, pitch, and torsion, resulting in poor adaptability. Furthermore, existing devices are sensitive to environmental interference; humidity, dust, and temperature changes can easily cause performance drift of optical components, further reducing alignment stability. In addition, traditional devices rely on repeated manual fine-tuning, resulting in low alignment efficiency and a lack of visual alignment references, making them difficult for beginners to learn and unsuitable for high-speed testing or field applications.

[0004] With the widespread application of optical technology in aerospace, semiconductors, laser processing, and other fields, the shortcomings of existing alignment devices in terms of accuracy, degrees of freedom, environmental adaptability, and ease of operation have become increasingly prominent, becoming a bottleneck restricting technological upgrades in related fields. Therefore, developing a laser interferometric alignment device with multi-degree-of-freedom precise adjustment, high-precision sensing feedback, strong environmental adaptability, and convenient operation to solve the problems of low alignment accuracy, single dimension, and poor environmental adaptability in traditional technologies has become an urgent need for industry development. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-degree-of-freedom adjustable laser interferometric alignment device, which solves the problems of low alignment accuracy, insufficient multi-dimensional error correction capability, poor environmental adaptability, and cumbersome operation of traditional devices, and meets the high-precision multi-degree-of-freedom alignment requirements of high-power laser communication, laser nuclear fusion and other scenarios.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a multi-degree-of-freedom adjustable laser interferometric alignment device, comprising a frame, a main optical path channel fixedly installed on one side of the frame, a polarizing beam splitter fixedly installed in the middle of the main optical path channel with an installation tilt angle of 45°, a fixed waveplate fixedly installed inside the main optical path channel near the lower part of the polarizing beam splitter, a polarization state sensor fixedly installed inside the main optical path channel between the polarizing beam splitter and the fixed waveplate, a beam splitter mirror fixedly installed on the lower side of the main optical path channel with an installation tilt angle of 45°, a first beam splitter channel fixedly installed on the upper part of one side of the main optical path channel near the polarizing beam splitter, a non-polarizing beam splitter fixedly installed in the middle of the first beam splitter channel, a first cemented double lens group fixedly installed on the side of the first beam splitter channel away from the main optical path channel, and a first beam splitter fixedly installed at the top of the first beam splitter channel near the non-polarizing beam splitter. A first beam-splitting branch channel has a semi-reflective mirror assembly fixedly installed in its inner center at a 45° angle. A polarizer array is fixedly installed at the top inner edge of the first beam-splitting branch channel. A second beam-splitting branch channel is fixedly installed on one side of the first beam-splitting branch channel near the semi-reflective mirror assembly. A second cemented double lens assembly is fixedly installed in its inner center. A fixed polarizer array is located on the inner side of the second beam-splitting branch channel away from the first beam-splitting branch channel. A microlens array is installed. A second beam splitter is fixedly installed on the lower part of one side of the main optical path channel. A sealed chamber is fixedly installed on the inner bottom of the frame near the lower part of the main optical path channel. Three right hinge supports are fixedly installed on one end of the sealed chamber near the main optical path channel. Two electric cylinders are movably installed on the outer ends of each right hinge support. The ends of the electric cylinders on the corresponding sides are movably installed on one end of a left hinge support. The outer ends of each left hinge support are fixedly installed on one end of a fixing ring. A collimating lens group is fixedly installed in the middle of the fixing ring.

[0007] An adjustable focus beam expander is installed on the upper side of the main optical path channel, and a focusing objective lens group is fixedly installed inside the main optical path channel near the lower part of the adjustable focus beam expander.

[0008] An adjustable focus lens is fixedly installed inside the first beam splitting channel on the side near the main beam path channel, and an electrically rotating waveplate is fixedly installed inside the first beam splitting channel on the side near the adjustable focus lens.

[0009] A ground glass plate is fixedly installed inside the second beam splitting channel. An alignment imaging lens group is fixedly installed inside the second beam splitting channel at a position away from the main beam path channel. A cross-shaped reticle is fixedly installed inside the second beam splitting channel at a position between the ground glass plate and the alignment imaging lens group. A marker dot is provided at the center of one end of the ground glass plate near the main beam path channel.

[0010] A laser emitting group is fixedly installed on one side of the top wall of the rack near the upper position of the main optical path channel. A first high-speed CMOS imaging target is fixedly installed on the other side of the top wall of the rack near the upper position of the first beam splitting branch channel. A second high-speed CMOS imaging target is fixedly installed on one end of the inner side wall of the rack near the end of the second beam splitting channel. A second CCD imaging target is fixedly installed on the other end of the inner side wall of the rack near the end of the first beam splitting channel. A first CCD imaging target is fixedly installed on the other end of the inner side wall of the rack near the end of the second beam splitting branch channel.

[0011] A narrowband filter lens is fixedly installed inside the sealed chamber on the side closest to the main optical path channel, and a plane wedge mirror is fixedly installed inside the sealed chamber on the side closest to the narrowband filter lens.

[0012] An adjusting cylinder is fixedly installed at one end of the sealed chamber away from the main optical path channel. The driving end of the adjusting cylinder extends into the interior of the sealed chamber and is fixedly installed on a placement platform. An auxiliary reflector is fixedly installed on the top of the placement platform near the adjusting cylinder.

[0013] A nitrogen inlet pipe is fixedly installed on one side of the sealed chamber, and a nitrogen outlet pipe is fixedly installed on the other side of the sealed chamber. A door is hinged to the front end of the sealed chamber.

[0014] This invention provides a multi-degree-of-freedom adjustable laser interferometric alignment device. It has the following advantages:

[0015] 1. This invention employs a combination structure of three sets of electric cylinders, hinged supports, and fixed rings to drive the collimating lens group to achieve multi-degree-of-freedom adjustment of translation and rotation. This can accurately correct multi-dimensional errors such as optical axis offset and tilt angle deviation, achieving alignment accuracy at the sub-micron level. It solves the pain points of traditional devices such as "difficulty in aligning light spots and insufficient resolution". The polarization state sensor and the electric rotating waveplate form a closed-loop feedback to correct laser polarization state drift in real time. Combined with narrow-band filter lenses to filter ambient light interference, the signal-to-noise ratio of interference fringes is improved by more than 3 times, further ensuring the stability of alignment accuracy.

[0016] 2. In the second beam splitting channel of this invention, the cross-shaped reticle and the marker mark on the ground glass plate work together to form a visual alignment reference on the second high-speed CMOS imaging target surface. The operator can intuitively judge the spot overlap state, greatly shortening the alignment preparation time. The coordinated feedback of multiple imaging target surfaces and sensor data can be linked with the electric adjustment component to achieve automatic alignment without repeated manual fine-tuning. The single alignment time is compressed from minutes to seconds, which is suitable for high-frequency testing requirements.

[0017] 3. The sealed chamber of this invention is filled with inert gas through a nitrogen inlet / outlet pipe to isolate it from humid, dusty, and corrosive environments, preventing condensation or contamination of components. It is suitable for complex environments such as marine laser communication and industrial sites. The combination design of the adjustable beam expander and adjustable lens allows for flexible adjustment of beam parameters according to the test field of view and component aperture. Without replacing core components, it can adapt to various scenarios such as ultra-wide field of view acquisition and long-distance transmission detection. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention;

[0019] Figure 2 This is a schematic diagram of the main optical path channel in this invention;

[0020] Figure 3 This is a schematic diagram of the sealed chamber structure in this invention;

[0021] Figure 4 This is a schematic diagram of the internal structure of the sealed chamber in this invention;

[0022] Figure 5 This is a front view of the present invention.

[0023] The components include: 1. Frame; 2. Main optical path channel; 3. Adjustable focus beam expander; 4. Focusing objective lens group; 5. Polarizing beam splitter prism; 6. Polarization state sensor; 7. Fixed waveplate; 8. Beam splitter mirror; 9. First beam splitter channel; 10. Adjustable focus lens; 11. Motorized rotating waveplate; 12. Unpolarizing beam splitter prism; 13. First cemented double lens group; 14. First beam splitter branch channel; 15. Semi-reflective semi-transparent lens group; 16. Polarizer array; 17. Second beam splitter branch channel; 18. Second cemented double lens group; 19. Microlens array; 20. Second beam splitter channel; 21. Ground glass. 21. Imaging lens group; 22. Cross-shaped reticle lens; 23. Laser emission group; 24. First high-speed CMOS imaging target surface; 25. Second high-speed CMOS imaging target surface; 26. First CCD imaging target surface; 27. Second CCD imaging target surface; 28. Sealed chamber; 29. ​​Right hinge support; 30. Electric cylinder; 31. Left hinge support; 32. Fixing ring; 33. Collimating lens group; 34. Narrow band filter lens; 35. Plane wedge mirror; 36. Adjusting cylinder; 37. Placement stage; 38. Auxiliary reflector; 49. Nitrogen inlet pipe; 40. Nitrogen outlet pipe; 41. Chamber door. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example:

[0026] Please see the appendix Figure 1 -Appendix Figure 5 This invention provides a multi-degree-of-freedom adjustable laser interferometric alignment device, such as... Figure 1As shown, the system includes a frame 1 constructed from 40×40mm industrial aluminum profiles, with overall dimensions of 800mm (length) × 500mm (width) × 600mm (height). Corner braces are added to the frame nodes for reinforcement. The resonant frequency is ≥50Hz, and the surface is anodized for corrosion resistance. Multiple standardized mounting holes are provided for easy component expansion. A main optical path channel 2 is fixedly installed on one side of the frame 1. This main optical path channel 2 is made of seamless stainless steel tubing with an inner diameter of 80mm and a wall thickness of 5mm. The inner wall is precision polished to a roughness Ra≤0.8μm to ensure no additional scattering of the beam. A polarizing beam splitter 5 is fixedly installed in the center of the main optical path channel 2 at a 45° tilt angle. The polarizing beam splitter 5 has a Φ50mm aperture, a strictly controlled splitting ratio of 1:1, and a surface accuracy PV≤λ / 20, enabling precise polarization separation. A fixed... Waveplate 7, the fixed waveplate 7 is adapted to the 632.8nm laser wavelength, with a phase delay accuracy of λ / 100, is made of quartz crystal, and has a light-transmitting aperture of Φ45mm. It can stably correct the laser polarization direction and ensure the stability of subsequent interference signals. A polarization state sensor 6 is fixedly installed inside the main optical path channel 2, located between the polarization beam splitter prism 5 and the fixed waveplate 7. The polarization state sensor 6 has a detection accuracy of ±0.1°, a response time of ≤1ms, and a sampling frequency of 1000Hz. It can capture laser polarization state drift data in real time and feed it back to the control system. A beam splitter mirror 8 is fixedly installed on the lower side inside the main optical path channel 2, and the installation tilt angle of the beam splitter mirror 8 is 45°. The light-transmitting mirror 8 has a light-transmitting aperture of Φ50mm, a reflectivity of ≥49.9%, a surface shape accuracy of PV≤λ / 20, a 632.8nm high-reflectivity coating on the reflective surface, and an anti-reflection coating on the rear surface, with a transmittance of ≥49.9%. It can achieve efficient beam splitting with light loss ≤0.01%.

[0027] In this embodiment, a first beam-splitting channel 9 is fixedly installed on the upper part of one side of the main optical path channel 2, near the polarizing beam-splitting prism 5. The first beam-splitting channel 9 is made of aluminum alloy tube with an inner diameter of 60mm and a wall thickness of 4mm. It is rigidly connected to the main optical path channel 2 via a flange, with a coaxiality deviation ≤0.02mm. A non-polarizing beam-splitting prism 12 is fixedly installed in the middle of the first beam-splitting channel 9. The non-polarizing beam-splitting prism 12 has a light transmission aperture of Φ40mm, is polarization-independent, has a P-light and S-light splitting ratio of 1:1, a light transmittance ≥99.5%, and a surface shape accuracy PV≤λ / 15, enabling uniform beam splitting. A first cemented double lens group 13 is fixedly installed on the side of the first beam-splitting channel 9 away from the main optical path channel 2. The first cemented double lens group 13 is integrally cemented together from two quartz lenses with different curvatures, with a focal length of 100mm. With a numerical aperture of 0.15, a double telecentric design, no air gap, light loss ≤0.5%, and surface accuracy PV≤λ / 15, it can achieve high-precision focusing imaging with a small range. A first beam splitting branch channel 14 is fixedly installed at the top of the first beam splitting channel 9 near the position of the non-polarizing beam splitter prism 12. The first beam splitting branch channel 14 is made of aluminum alloy tube with an inner diameter of 50mm and a wall thickness of 3mm. It is perpendicularly welded to the first beam splitting channel 9 with a perpendicularity deviation ≤0.01mm. A semi-reflective mirror group 15 is fixedly installed in the middle of the first beam splitting branch channel 14 with an installation tilt angle of 45°. The semi-reflective mirror group 15 has a light transmission diameter of Φ40mm, a reflectivity of 50%±2%, a transmittance of 50%±2%, and a surface accuracy PV≤λ / 20. It is coated with a neutral density film to achieve unbiased beam splitting.

[0028] Furthermore, a polarizer array 16 is fixedly installed on the inner top of the first beam-splitting branch channel 14. The polarizer array 16 includes four uniformly distributed polarization directions: 0°, 45°, 90°, and 135°. It has a light-transmitting aperture of Φ30mm, an extinction ratio ≥1000:1, and a transmittance ≥98%, and can simultaneously acquire interference images of different polarization states. A second beam-splitting branch channel 17 is fixedly installed on one side of the first beam-splitting branch channel 14 near the semi-reflective mirror group 15. The second beam-splitting branch channel 17 is made of aluminum alloy tubing with an inner diameter of 50mm and a wall thickness of 3mm. It is fixed to the first beam-splitting branch channel 14 via a quick-locking mechanism, with a repeatability deviation ≤0.0. A second cemented double lens group 18 is fixedly installed in the middle of the second beam splitting branch channel 17. The second cemented double lens group 18 has a focal length of 80mm, a numerical aperture of 0.2, a double telecentric design, a surface accuracy PV≤λ / 15, and a light transmission diameter of Φ40mm. It can adapt to the focusing requirements of large-range beams. A microlens array 19 is fixedly installed on the side of the second beam splitting branch channel 17 away from the first beam splitting branch channel 14. The microlens array 19 is a 50×50 array distribution, with a single lens diameter of Φ2mm, a focal length of 15mm, a fill factor ≥95%, and is made of optical glass. It can convert interference beams into array light spots, improving the resolution of large-range tests.

[0029] Furthermore, a second beam splitting channel 20 is fixedly installed on the lower side of one side of the main optical path channel 2. The second beam splitting channel 20 is made of aluminum alloy tube with an inner diameter of 60mm and a wall thickness of 4mm. It is fixed at a 30° angle with the main optical path channel 2, ensuring a smooth and unobstructed light path. A sealed chamber 29 is fixedly installed on the inner bottom of the frame 1 near the lower part of the main optical path channel 2. The sealed chamber 29 is made of stainless steel, with a length of 300mm × width of 200mm × height of 200mm and a sealing rating of IP65, effectively isolating external dust and moisture interference. Three right hinge supports 30 are fixedly installed on one end of the sealed chamber 29 near the main optical path channel 2. The right hinge supports 30 are made of aviation aluminum with a strength ≥300MPa, arranged in an equilateral triangle with a spacing of 120mm. Two electric cylinders 31 are movably installed on the outer ends of each right hinge support 30. The electric cylinders 31 have a stroke of 50mm. The positioning accuracy is ±0.1μm, the maximum thrust is 100N, the response frequency is 100Hz, and the ball screw drive is used. The operation is smooth and vibration-free. The ends of the electric cylinders 31 on the corresponding sides are movably installed at one end of the left hinge support 32. The left hinge support 32 and the right hinge support 30 have the same structure and material to ensure the symmetry of force transmission. The outer ends of the left hinge support 32 are fixedly installed at one end of the fixing ring 33. The fixing ring 33 is made of titanium alloy, with an inner diameter of 60mm and a coaxiality of ≤0.01mm. It is fixed to the left hinge support 32 by welding, which is rigid and deformation-free. The middle of the fixing ring 33 is fixedly installed with a collimating lens group 34. The collimating lens group 34 has a light transmission diameter of Φ60mm, a focal length of 200mm, a collimation accuracy of ≤0.1mrad, and a surface accuracy of PV≤λ / 20. It can convert divergent beams into parallel beams and provide a stable light source for interferometric testing.

[0030] Furthermore, an adjustable focus beam expander 3 is installed on the upper side of the main optical path channel 2. The adjustable focus beam expander 3 has an adjustable beam expansion ratio of 1:2 to 1:3, a light-transmitting aperture of Φ40mm, a transmittance of ≥99.8%, and an adjustment accuracy of ±0.01mm. It can flexibly adjust the beam aperture according to the test field requirements, adapting to ultra-wide field-of-view capture and small field-of-view high-precision test scenarios. A focusing objective lens group 4 is fixedly installed inside the main optical path channel 2 near the lower position of the adjustable focus beam expander 3. The focusing objective lens group 4 has a focal length of 50mm, a numerical aperture of 0.25, a surface shape accuracy of PV≤λ / 15, and a focused spot diameter of ≤10μm. It can focus the beam output by the laser emission group 24 into a standard spherical wave, laying the foundation for subsequent interferometric testing.

[0031] Furthermore, an adjustable focus lens 10 is fixedly installed inside the first beam splitting channel 9 on the side near the main beam channel 2. The adjustable focus lens 10 has a focal length adjustment range of 50~100mm, a light-transmitting aperture of Φ40mm, a transmittance of ≥99.5%, and an adjustment accuracy of ±0.01mm. It can limit stray light interference by changing the focal length and adapt to the testing requirements of test components with different apertures. An electric rotating waveplate 11 is fixedly installed inside the first beam splitting channel 9 on the side near the adjustable focus lens 10. The electric rotating waveplate 11 is adapted to a wavelength of 632.8nm, has a rotation angle range of 0~360°, a positioning accuracy of ±0.01°, and a response time of ≤5ms. It can correct the beam polarization state in real time according to the feedback of the polarization state sensor 6 to ensure the clarity of the interference fringes.

[0032] Furthermore, a frosted glass plate 21 is fixedly installed inside the second beam-splitting channel 20. The frosted glass plate 21 has a light-transmitting aperture of Φ40mm, a haze of 50%, a transmittance of ≥85%, and is made of borosilicate glass with a uniformly frosted surface, enabling the beam to form a uniformly diffused light spot. A marker point is provided at the center of one end of the frosted glass plate 21 near the main beam-splitting channel 2. The marker point has a diameter of 0.1mm and a positioning accuracy of ±0.01mm, providing a clear reference point for alignment. An alignment imaging lens group 22 is fixedly installed inside the second beam-splitting channel 20 at a position away from the main beam-splitting channel 2. The focal length of the alignment imaging lens group 22 is... With a magnification of 120mm, a magnification of 5x, a resolution of ≤1μm, and a light transmission aperture of Φ40mm, it can clearly image the light spot on the ground glass plate 21 onto the second high-speed CMOS imaging target surface 26. Inside the second beam splitting channel 20, a cross-shaped reticle 23 is fixedly installed at a position between the ground glass plate 21 and the alignment imaging lens group 22. The cross-shaped reticle 23 has a light transmission aperture of Φ40mm, a reticle line width of 0.01mm, a center positioning accuracy of ±0.005mm, a transmittance of ≥99.5%, and uses a quartz glass substrate. It can provide a visual alignment reference, making it easy for operators to intuitively judge the light spot overlap status.

[0033] Furthermore, a laser emitting group 24 is fixedly installed on one side of the top wall of the rack 1 near the upper part of the main optical path channel 2. The laser emitting group 24 is a 632.8nm helium-neon laser with an output power of 5mW, a linewidth ≤1kHz, a frequency stability ≤±1MHz / h, a divergence angle of 0.5mrad, and a beam quality M²≤1.1, capable of outputting stable monochromatic laser. On the other side of the top wall of the rack 1, near the upper part of the first beam splitting branch channel 14, a first high-speed CMOS imaging target surface 25 is fixedly installed. The first high-speed CMOS imaging target surface 25 has 1024 pixels × 1024 pixels, a frame rate of 100fps, a quantum efficiency ≥95%, a readout noise ≤1e⁻, and a dynamic range of 65dB, capable of rapidly acquiring polarization state correlation interference images. On one end of the inner side wall of the rack 1, near the end of the second beam splitting channel 20, a second high-speed CMOS imaging target surface 26 is fixedly installed. The second high-speed CMOS imaging target surface 26 has 1024 pixels × 1024 pixels. The device features 1024 pixels, a frame rate of 150fps, quantum efficiency ≥90%, readout noise ≤2e⁻, and a dynamic range of 60dB. It can display the real-time alignment of the beam spot with the center of the crosshair. A second CCD imaging target surface 28 is fixedly mounted at the other end of the inner wall of the frame 1, near the end of the first beam splitting channel 9. This second CCD imaging target surface 28 has 1024 pixels × 1024 pixels, a dynamic range of 60dB, and dark current ≤0.01e⁻ / p. With a readout speed of 10MHz, it can achieve high-precision surface shape detection and imaging with a small range. The first CCD imaging target 27 is fixedly installed at the other end of the inner sidewall of the frame 1 near the end of the second beam splitting branch channel 17. The first CCD imaging target 27 has 1024 pixels × 1024 pixels, a dynamic range of 65dB, a dark current ≤0.005e⁻ / pixel / s, and a readout speed of 15MHz. It can acquire large-range array spot interference images.

[0034] Furthermore, a narrowband filter 35 is fixedly installed inside the sealed chamber 29 on the side near the main optical path channel 2. The narrowband filter 35 has a center wavelength of 632.8nm, a bandwidth of ≤10nm, a transmittance of ≥98%, and a cutoff depth of OD6. It can effectively filter external ambient light interference and improve the signal-to-noise ratio of interference fringes. A planar wedge mirror 36 is fixedly installed inside the sealed chamber 29 on the side near the narrowband filter 35. The planar wedge mirror 36 has a light-transmitting aperture of Φ200mm, a wedge angle of 6 minutes ±10″, a first surface being the wedge angle surface coated with a 632.8nm anti-reflection film, and a transmittance of >99.88%. The second surface is a standard reference plane, perpendicular to the optical axis of the collimating lens group 34, with a surface accuracy PV≤30nm. It cooperates with the auxiliary reflector 39 to form a standard interference test cavity.

[0035] Furthermore, an adjusting cylinder 37 is fixedly installed at the end of the sealed chamber 29 away from the main optical path channel 2. The adjusting cylinder 37 has a stroke of 0~200mm, a positioning accuracy of ±0.1μm, a working pressure of 0.4~0.8MPa, and adopts pneumatic servo control, ensuring smooth and shock-free operation. The drive end of the adjusting cylinder 37 extends into the interior of the sealed chamber 29 and is fixedly installed on a placement stage 38. The placement stage 38 is made of aluminum alloy, with dimensions of 150mm×150mm×20mm, a levelness of ≤0.02mm / m, and an anodized surface treatment, enabling stable placement of test components of different sizes. An auxiliary reflector 39 is fixedly installed on the top of the placement stage 38 near the adjusting cylinder 37. The auxiliary reflector 39 has a light-transmitting aperture of Φ100mm, a reflective reference surface shape accuracy of PV≤50nm, a reflectivity of ≥99.9%, is perpendicular to the optical axis of the collimating lens group 34, and forms an interference cavity with the standard reference plane of the planar wedge mirror 36, adapting to the testing requirements of test components of different thicknesses.

[0036] Furthermore, a nitrogen inlet pipe 40 is fixedly installed on one side of the sealed chamber 29. The nitrogen inlet pipe 40 is made of stainless steel, with a diameter of Φ10mm, a wall thickness of 2mm, and a G1 / 4 threaded interface. It can be connected to a nitrogen source to fill the chamber with dry inert gas. A nitrogen outlet pipe 41 is fixedly installed on the other side of the sealed chamber 29. The nitrogen outlet pipe 41 has the same structure as the nitrogen inlet pipe 40 and can discharge humid air or pollutants from the chamber, maintaining a dry and clean environment inside the chamber. A chamber door 42 is hinged to the front end of the sealed chamber 29. The chamber door 42 is made of stainless steel, equipped with a fluororubber sealing ring, a sealing pressure ≥0.1MPa, and a side-opening type. It is equipped with a door lock device to facilitate the loading, unloading, and maintenance of the components under test, while ensuring the sealing performance of the chamber.

[0037] Working principle:

[0038] Step 1: Laser Emission and Initial Optical Path Calibration

[0039] The laser emitted by the laser emitting group 24 first enters the main optical path channel 2. After being expanded by the adjustable focus beam expander 3, it is focused by the focusing objective lens group 4 to form a standard spherical wave. The adjustable focus beam expander 3 can adjust the beam aperture according to the test field requirements. The spherical wave passes through the polarization state separation of the polarization beam splitter 5, the real-time monitoring of the laser polarization state change by the polarization state sensor 6, and the correction of the polarization direction by the fixed wave plate 7, and finally shines on the beam splitter mirror 8 installed at a 45° angle.

[0040] Step 2: Optical Path Splitting: Signal Distribution Between the Main Optical Path and the Two Splitting Paths

[0041] The beam splitter 8 splits the incident light into two paths. One path is reflected to the second beam splitter channel 20 for alignment monitoring, while the other path is transmitted and continues to propagate along the main beam channel 2, eventually entering the sealed chamber 29 for interference testing. At the same time, the polarizing beam splitter 5 guides part of the reflected light into the first beam splitter channel 9. This beam passes through the adjustable focus lens 10 to adjust the beam convergence and suppress stray light. The electric rotating waveplate 11 corrects the polarization state in real time based on feedback from the polarization state sensor. After reaching the non-polarizing beam splitter 12, it is split into two branches again.

[0042] Step 3: Alignment and Adjustment: Visual Positioning and Precise Multi-DOF Correction

[0043] Within the second beam splitting channel 20, the beam first illuminates the ground glass plate 21. The marker dot on the front end of the ground glass plate 21 serves as a positioning reference. Then, the crosshair reticle 23 provides a visual alignment reference. The beam is then imaged onto the second high-speed CMOS imaging target surface 26 by the alignment imaging lens group 22. The operator or automatic alignment algorithm determines the beam alignment deviation by observing the "coincidence degree between the focused spot of the marker dot and the center of the crosshair reticle". This drives the three sets of electric cylinders 31 outside the sealed chamber 29 to move the collimating lens group 34 to achieve multi-degree-of-freedom adjustment, including translation in the horizontal and vertical directions, as well as pitch angle adjustment, torsion angle adjustment and roll angle adjustment by coordinating the telescopic control of the collimating lens group 34, until the spot completely coincides with the center of the crosshair, completing the initial alignment.

[0044] Step 4: Interference Testing: Dual-Range Imaging and Accuracy Verification

[0045] Inside the sealed chamber 29, the main optical beam, after being filtered by a narrow-band filter 35 to remove ambient light interference and by a planar wedge mirror 36 providing a standard reference plane, forms an interference signal with the reflected light from the component under test placed on the stage 38. The interference signal returns along the original optical path to the two branches of the first beam splitting channel 9. The position can be adjusted by adjusting the cylinder 37 to accommodate components of different thicknesses. The transmitted light from the non-polarizing beam splitter 12 of the first branch is focused by the first cemented double lens group 13 and imaged onto the second CCD imaging target surface 28, achieving high-precision surface shape detection. The reflected light from the non-polarizing beam splitter 12 of the second branch enters the first beam splitting branch channel 14. After passing through the semi-reflective lens group 15, one branch is imaged onto the first high-speed CMOS imaging target surface 25 through the polarizer array 16, and the other branch is imaged onto the first CCD imaging target surface 27 through the second cemented double lens group 18 and the microlens array 19 of the second beam splitting branch channel 17, achieving wide-range interference signal acquisition.

[0046] Step 5: Environment Adaptation and Closed-Loop Optimization

[0047] The sealed chamber 29 is filled with inert gas through the nitrogen inlet pipe 40 and the nitrogen outlet pipe 41 to avoid the influence of humid, dusty or corrosive environments on optical components and ensure the stability of interference signals. The chamber door 42 facilitates the loading, unloading and maintenance of the components under test. The real-time data of the polarization state sensor 6 and each imaging target surface are fed back to the control system. Combined with the dynamic adjustment of the electric rotating waveplate 11 and the adjustable focusing lens 10, a "alignment-detection-compensation" closed loop is formed to ensure the alignment accuracy during long-term operation.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-degree-of-freedom adjustable laser interferometric alignment device, comprising a frame (1), characterized in that, A main optical path channel (2) is fixedly installed on one side of the frame (1). A polarizing beam splitter (5) is fixedly installed in the middle of the main optical path channel (2), and the installation tilt angle of the polarizing beam splitter (5) is 45°. A fixed waveplate (7) is fixedly installed inside the main optical path channel (2) near the lower part of the polarizing beam splitter (5). A polarization state sensor (6) is fixedly installed inside the main optical path channel (2) at the position between the polarizing beam splitter (5) and the fixed waveplate (7). A beam splitter mirror (8) is fixedly installed on the lower side of the main optical path channel (2), and the installation tilt angle of the beam splitter mirror (8) is 45°. At an angle of 45°, a first beam-splitting channel (9) is fixedly installed on the upper part of one side of the main optical path channel (2) near the polarizing beam-splitting prism (5). A non-polarizing beam-splitting prism (12) is fixedly installed in the middle of the first beam-splitting channel (9). A first cemented double lens group (13) is fixedly installed on the side of the first beam-splitting channel (9) away from the main optical path channel (2). A first beam-splitting branch channel (14) is fixedly installed at the top of the first beam-splitting channel (9) near the non-polarizing beam-splitting prism (12). A semi-reflective semi-transparent lens group (15) is fixedly installed in the middle of the first beam-splitting branch channel (14). The installation tilt angle of the semi-reflective mirror group (15) is 45°. A polarizer array (16) is fixedly installed on the inner top of the first beam splitter branch channel (14). A second beam splitter branch channel (17) is fixedly installed on one side of the first beam splitter branch channel (14) near the semi-reflective mirror group (15). A second cemented double lens group (18) is fixedly installed in the middle of the second beam splitter branch channel (17). A microlens array (19) is fixedly installed on the side of the second beam splitter branch channel (17) away from the first beam splitter branch channel (14). The lower part of one side of the main optical path channel (2) A second beam splitter channel (20) is fixedly installed. A sealed chamber (29) is fixedly installed at the bottom of the frame (1) near the main beam channel (2). Three right hinge supports (30) are fixedly installed at one end of the sealed chamber (29) near the main beam channel (2). Two electric cylinders (31) are movably installed on the outer ends of the right hinge supports (30). The ends of the electric cylinders (31) on the corresponding sides are movably installed on one end of the left hinge support (32). The outer ends of the left hinge support (32) are fixedly installed on one end of the fixing ring (33). A collimating lens group (34) is fixedly installed in the middle of the fixing ring (33).

2. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, An adjustable focus beam expander (3) is installed on the upper side inside the main optical path channel (2), and a focusing objective lens group (4) is fixedly installed inside the main optical path channel (2) near the lower position of the adjustable focus beam expander (3).

3. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, An adjustable focus lens (10) is fixedly installed inside the first beam splitting channel (9) on the side near the main beam channel (2), and an electric rotating waveplate (11) is fixedly installed inside the first beam splitting channel (9) on the side near the adjustable focus lens (10).

4. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, A ground glass plate (21) is fixedly installed inside the second beam splitting channel (20). An alignment imaging lens group (22) is fixedly installed inside the second beam splitting channel (20) at a position away from the main beam channel (2). A cross-shaped reticle (23) is fixedly installed inside the second beam splitting channel (20) at a position between the ground glass plate (21) and the alignment imaging lens group (22). A marker mark is provided at the middle of one end of the ground glass plate (21) near the main beam channel (2).

5. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, A laser emission group (24) is fixedly installed on one side of the top wall of the rack (1) near the upper position of the main optical path channel (2). A first high-speed CMOS imaging target (25) is fixedly installed on the other side of the top wall of the rack (1) near the upper position of the first beam splitting branch channel (14). A second high-speed CMOS imaging target (26) is fixedly installed on one end of the inner wall of the rack (1) near the end of the second beam splitting channel (20). A second CCD imaging target (28) is fixedly installed on the other end of the inner wall of the rack (1) near the end of the first beam splitting channel (9). A first CCD imaging target (27) is fixedly installed on the other end of the inner wall of the rack (1) near the end of the second beam splitting branch channel (17).

6. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, A narrow-band filter (35) is fixedly installed inside the sealed chamber (29) on the side near the main optical path channel (2), and a plane wedge mirror (36) is fixedly installed inside the sealed chamber (29) on the side near the narrow-band filter (35).

7. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, An adjusting cylinder (37) is fixedly installed at one end of the sealed chamber (29) away from the main optical path channel (2). The driving end of the adjusting cylinder (37) extends into the interior of the sealed chamber (29) and is fixedly installed on a placement platform (38). An auxiliary reflector (39) is fixedly installed on the top of the placement platform (38) near the adjusting cylinder (37).

8. The multi-degree-of-freedom adjustable laser interferometric alignment device according to claim 1, characterized in that, A nitrogen inlet pipe (40) is fixedly installed on one side of the sealed chamber (29), and a nitrogen outlet pipe (41) is fixedly installed on the other side of the sealed chamber (29). A chamber door (42) is hinged to the front end of the sealed chamber (29).

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