A large aperture multi-parameter testing device and method based on two-stage beam reduction

Abstract

The application discloses a large-aperture multi-parameter testing device and method based on double-stage beam narrowing, and relates to the technical field of laser parameter testing. The device comprises a box body and an optical system. The optical system comprises a first-stage beam narrowing device, a second-stage beam narrowing device and a light splitting testing assembly. The first-stage beam narrowing device is of an off-axis two-mirror structure. The second-stage beam narrowing device is of a transmission mirror tube structure and is used for performing secondary beam narrowing on the primary beam and prolonging the exit pupil distance to obtain a main light path beam. The light splitting testing assembly comprises a light splitting element and multiple testing branches. The light splitting element is used for synchronously splitting the main light path beam into the multiple testing branches. The multiple testing branches comprise a near-field light spot collecting branch, a beam pointing testing branch, a time characteristic measuring branch and a spectral characteristic collecting branch. The device is compact in structure, high in integration and high in measurement accuracy, and can realize efficient, accurate and integrated synchronous testing of multi-parameters of a large-aperture laser beam.

Description

Technical Field

[0001] This invention relates to the technical field of laser parameter testing, and in particular to a large-aperture multi-parameter testing device and method based on dual-stage beam contraction. Background Technology

[0002] High-energy laser systems have wide applications in industrial processing, scientific research, and other fields. Parameters such as the near-field spot size, far-field distribution, beam pointing, time waveform, and spectral characteristics of the laser beam are key indicators for evaluating the performance of a laser system. Accurate and comprehensive measurement of laser beam parameters is an indispensable and crucial step in laser research and development, production quality control, and optical system integration and debugging.

[0003] As application demands continue to deepen, the output aperture and power of laser systems are constantly increasing, posing new challenges to laser parameter testing technology. On the one hand, large-aperture beams cannot be directly matched with the limited aperture of conventional detectors, and must be adapted using high-fidelity beam-shrinking optical systems. This requires the beam-shrinking system itself to have extremely high image quality and stability to avoid introducing additional measurement errors. On the other hand, a complete evaluation of beam quality often requires the simultaneous acquisition of parameters in multiple dimensions. However, traditional testing schemes based on multiple separate devices have limitations in optical path integration, system calibration, and operational efficiency, making it difficult to meet the demands of high-efficiency and highly integrated modern testing.

[0004] Therefore, developing an integrated testing technology that can adapt to large-aperture beams, achieve synchronous high-precision measurement of multiple parameters, and possess good engineering practicality, environmental adaptability, and long-term operational reliability is of great significance for promoting the research and application of high-end laser equipment. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a large-aperture multi-parameter testing device and method based on dual-stage beam contraction. The device has a compact structure, high integration, and high measurement accuracy, and can achieve efficient, accurate, and integrated synchronous testing of multiple parameters of large-aperture laser beams.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a large-aperture multi-parameter testing device based on dual-stage beam shrinking, the device comprising a housing and an optomechanical system integrated in a sealed optical path environment within the housing; the optomechanical system comprising a first-stage beam shrinker, a second-stage beam shrinker, and a beam splitting testing component arranged sequentially along the optical path direction. The primary beam shrinker is an off-axis two-reflector structure, used for primary beam shrinking of incident large-aperture laser beams. The secondary beam shrinker is a transmission-type lens tube structure, used to perform secondary beam shrinking on the beam after primary beam shrinking and extend the exit pupil distance to obtain the main optical path beam. The beam splitting test assembly includes a beam splitting element and multiple test branches. The beam splitting element is used to synchronously split the main optical path beam into the multiple test branches. The multiple test branches include a near-field spot acquisition branch, a beam pointing test branch, a time characteristic measurement branch, and a spectral characteristic acquisition branch.

[0007] In one possible implementation, the primary beam reducer includes a primary mirror, a secondary mirror, and a support frame; The support frame is fixed inside the housing by a heat-dissipating connection module; the support frame is used to fix the position and angle of the primary mirror and the secondary mirror; the primary mirror is used to receive and converge the received large-aperture laser beam; the secondary mirror is located in the reflection optical path of the primary mirror and is used to reflect the beam converged by the primary mirror again and collimate it into a smaller diameter output beam.

[0008] In one possible implementation, the primary beam reducer further includes a six-dimensional adjustment mechanism, through which the secondary mirror is fixed to the support frame.

[0009] In one possible implementation, the secondary beam reducer includes a lens barrel and an optical lens group disposed within the lens barrel; the lens barrel is fixed inside the housing by a bracket, and the optical lens group is used to reduce the aperture of the parallel beam output from the primary beam reducer; Each lens in the optical lens group has an independent mechanical centering structure and is flexibly connected to the lens barrel by circumferential glue injection; the lens barrel is provided with ventilation holes.

[0010] In one possible implementation, the spectral testing assembly includes a first spectral splitter, a second spectral splitter, a third spectral splitter, a first camera, a far-field imaging lens, a second camera, a high-speed photodetector, and a fiber optic spectrometer. The first beam splitter is disposed at the output end of the secondary beam reducer and is used to split the main optical beam. The second beam splitter is disposed in the transmission optical path of the first beam splitter, and the third beam splitter is disposed in the reflection optical path of the first beam splitter. The first camera is positioned on the reflected light path of the third beam splitter, and together with the reflected light path of the first beam splitter and the reflected light path of the third beam splitter, they form the near-field spot acquisition branch. The far-field imaging lens is disposed on the transmission light path of the second beam splitter, and the second camera is connected to the far-field imaging lens, forming the beam pointing test branch together with the transmission light path of the first beam splitter and the transmission light path of the second beam splitter. The high-speed photodetector is disposed on the reflected light path of the second beam splitter, and together with the transmitted light path of the first beam splitter and the reflected light path of the second beam splitter, it forms the time characteristic measurement branch. The fiber optic spectrometer is positioned on the transmission optical path of the third beam splitter, and together with the reflection optical path of the first beam splitter and the transmission optical path of the third beam splitter, it forms the spectral characteristic acquisition branch.

[0011] In one possible implementation, the working surfaces of the first beam splitter, the second beam splitter, and the third beam splitter are all provided with wedge angles; The near-field spot acquisition branch, the beam pointing test branch, the time characteristic measurement branch, and the spectral characteristic acquisition branch are all equipped with attenuation mirror groups.

[0012] In one possible implementation, the attenuation lens assembly includes an attenuation plate that is mounted at an angle of 3 to 5 degrees to the optical axis.

[0013] In one possible implementation, the enclosure is equipped with a heat insulation board and a stray light shielding cylinder; The stray light shielding tube is disposed around the optical path of the secondary beam shrinker; The heat insulation plate is disposed on the outer periphery of the first camera, the second camera, and the fiber optic spectrometer, and together with the stray light shielding cylinder, forms a physical isolation zone for the heat source.

[0014] In one possible implementation, the enclosure includes a base plate and side plates disposed on the outer periphery of the base plate; the enclosure is also provided with a partition for dividing the enclosure into a main optical path cavity and an electrical compartment, and the heat control equipment of the test device is located in the electrical compartment; The base plate is made of titanium alloy, and the side plates and the partition are made of aluminum alloy. The side panel integrates a cooling fan and an aviation plug panel.

[0015] Secondly, the present invention provides a large-aperture multi-parameter testing method based on dual-stage beam contraction, applied to the large-aperture multi-parameter testing device based on dual-stage beam contraction described in any of the above claims, the method comprising: A large-aperture laser beam to be tested is introduced into the large-aperture multi-parameter testing device based on dual-stage beam contraction. The large-aperture laser beam under test is processed sequentially by a first-stage beam shrinker, a second-stage beam shrinker, and a beam splitting test component. Simultaneously, the near-field spot image of the near-field spot acquisition branch, the beam pointing angle of the beam pointing test branch, the time pulse waveform of the time characteristic measurement branch, and the spectral data of the spectral characteristic acquisition branch are acquired. The synchronously acquired near-field spot image, beam pointing angle, time pulse waveform, and spectral data are processed, and the multi-parameter measurement results are displayed.

[0016] The large-aperture multi-parameter testing device based on dual-stage beam shrinking provided in this invention integrates a dual-stage beam shrinking optical system with four functional testing branches for near-field spot, beam pointing, time characteristics, and spectral characteristics into a single enclosure. This achieves one-stop synchronous measurement of multiple parameters of large-aperture lasers, avoiding the errors and operational complexities introduced by connecting multiple measurement devices when performing multi-parameter testing on laser beams. This invention employs an off-axis two-mirror structure as the first-stage beam shrinker, effectively reducing aberrations in the optical system. It uses a transmission-type lens barrel structure as the second-stage beam shrinker, extending the exit pupil distance while simultaneously shrinking the beam, facilitating the integration of beam-splitting elements and multiple testing branches in subsequent beam-splitting testing components. Therefore, the testing device of this invention features a compact structure, high integration, and high measurement accuracy, enabling efficient, accurate, and integrated synchronous testing of multiple parameters of large-aperture laser beams. Attached Figure Description

[0017] Figure 1 A top view of a large-aperture multi-parameter testing device based on a dual-stage beam contraction provided in an embodiment of the present invention; Figure 2 A cross-sectional view of a large-aperture multi-parameter testing device based on a dual-stage beam contraction provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a six-dimensional adjustment mechanism for a large-aperture multi-parameter testing device based on a dual-stage beam contraction, provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of an aero-mounted panel of a large-aperture multi-parameter testing device based on a dual-stage beam contraction, provided in an embodiment of the present invention. Figure 5 The flowchart illustrates the steps of a large-aperture multi-parameter testing method based on dual-stage beam contraction, as provided in this embodiment of the invention.

[0018] Figure labels and descriptions: 1. Cabinet; 11. Base plate; 12. Side plate; 13. Partition; 14. Heat insulation plate; 15. Stray light shielding cylinder; 16. Cooling fan; 17. Aviation connector panel; 1701. Main power switch; 1702. Camera power switch; 1703. Fan switch; 1704. Main power socket; 1705. Network interface; 2. First-stage beam shortener; 21. Primary lens; 22. Secondary lens; 23. Support frame; 24. Heat dissipation connection module; 25. Six-dimensional adjustment mechanism; 251. Arc-shaped slot; 252. Gasket assembly; 253. First adjustment... 1. Main plate; 254. Second adjustment plate; 3. Secondary beam shrinker; 31. Lens tube; 32. Optical lens group; 33. Support; 34. Ventilation hole; 4. Beam splitter; 41. First beam splitter; 42. Second beam splitter; 43. Third beam splitter; 5. Near-field spot acquisition branch; 51. First camera; 6. Beam pointing test branch; 61. Far-field imaging lens; 62. Second camera; 7. Time characteristic measurement branch; 71. High-speed photodetector; 8. Spectral characteristic acquisition branch; 81. Fiber optic spectrometer; 9. Attenuator. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only 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.

[0020] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, the use of "based on" or "according to" implies openness and inclusiveness, because processes, steps, calculations, or other actions "based on" or "according to" one or more of the stated conditions or values ​​may in practice be based on additional conditions or beyond the stated values.

[0021] To overcome the shortcomings of existing technologies, this invention provides a large-aperture multi-parameter testing device and method based on dual-stage beam contraction. The device has a compact structure, high integration, and high measurement accuracy, and can achieve efficient, accurate, and integrated synchronous testing of multiple parameters of large-aperture laser beams.

[0022] like Figure 1 , Figure 2As shown, this embodiment of the invention provides a large-aperture multi-parameter testing device based on dual-stage beam contraction. The device includes a housing 1 and an optomechanical system integrated into a sealed optical path environment within the housing 1.

[0023] Specifically, the optomechanical system includes a first-stage beam shrinker 2, a second-stage beam shrinker 3, and a beam splitting test assembly arranged sequentially along the optical path.

[0024] The first-stage beam shrinker 2 is an off-axis two-reflector structure used for primary beam shrinking of incident large-aperture laser beams.

[0025] Among them, the first-stage beam reducer 2 of the off-axis two-reflector structure is composed of two off-axis aspherical mirrors. The light is refracted between the mirrors and there are no transmission elements. It has the advantages of no chromatic aberration, no central obstruction, high power handling and compact structure.

[0026] The secondary beam shortener 3 is a transmission-type lens tube structure, used to perform secondary beam shortening on the beam after primary beam shortening and extend the exit pupil distance to obtain the main optical path beam.

[0027] Among them, the secondary beam shrinker 3 of the transmission-type lens tube structure is realized by encapsulating a lens group inside a cylindrical lens tube, which has the advantages of low cost, mature assembly and adjustment technology, excellent image quality, good environmental adaptability, and continuously adjustable beam shrinkage ratio. The lens group can be Galilean type (positive and negative lens combination) or Keplerian type (double positive lens plus intermediate focal plane).

[0028] In this invention, the off-axis two-reflector structure primary beam shrinker 2 and the transmission-type lens tube structure secondary beam shrinker 3 work together to form a two-stage beam shrinking system. This system has the characteristics of being able to achieve large-aperture, unobstructed beam compression, excellent wide spectral range and chromatic aberration-free characteristics, aberration complementarity and controllable total system aberration, more reasonable beam shrinking ratio distribution, simpler assembly and adjustment, and the ability to suppress stray light and make subsequent optical path layout more flexible.

[0029] Specifically, the spectroscopic test assembly includes a spectroscopic element 4 and multiple test branches.

[0030] Beam splitter 4 is used to simultaneously split the main optical beam into multiple test branches.

[0031] Among them, multiple test branches include a near-field spot acquisition branch 5, a beam pointing test branch 6, a time characteristic measurement branch 7, and a spectral characteristic acquisition branch 8, which are used to realize the functional testing of the near-field spot, beam pointing, time characteristics, and spectral characteristics of the laser beam, respectively.

[0032] The large-aperture multi-parameter testing device based on dual-stage beam shrinking provided in this invention integrates a dual-stage beam shrinking optical system with four functional testing branches—near-field spot, beam pointing, time characteristics, and spectral characteristics—within a single housing 1. This achieves one-stop synchronous measurement of multiple parameters of large-aperture lasers, avoiding the errors and operational complexities introduced by connecting multiple measurement devices when performing multi-parameter testing on laser beams. This invention employs an off-axis two-mirror structure as the first-stage beam shrinker 2, effectively reducing optical system aberrations. It uses a transmission-type lens barrel structure as the second-stage beam shrinker 3, which extends the exit pupil distance while simultaneously shrinking the beam, facilitating the integrated layout of the beam splitter 4 and multiple testing branches in the subsequent beam splitting testing assembly. Therefore, the testing device of this invention features a compact structure, high integration, and high measurement accuracy, enabling efficient, accurate, and integrated synchronous testing of multiple parameters of large-aperture laser beams.

[0033] Furthermore, the primary beam reducer 2 includes a primary mirror 21, a secondary mirror 22, and a support frame 23.

[0034] The support frame 23 is fixed inside the housing 1 by the heat dissipation connection module 24; the support frame 23 is used to fix the position and angle of the primary mirror 21 and the secondary mirror 22; the primary mirror 21 is used to receive and converge the received large-aperture laser beam; the secondary mirror 22 is located in the reflection optical path of the primary mirror 21 and is used to reflect the beam converged by the primary mirror 21 again and collimate it into a smaller diameter output beam.

[0035] Among them, the heat-dissipating connection module 24 is a flexible mechanical structure specifically designed to solve the problem of thermal expansion and contraction. The heat-dissipating connection module 24 can ensure that the optical axis of the first-stage beam reducer 2 will not deviate due to the thermal expansion and contraction of the housing 1. The heat-dissipating connection module 24 can also absorb the deformation caused by the difference in thermal expansion coefficients between the first-stage beam reducer 2 and the housing 1, and avoid excessive internal stress at the connection between the two, which could lead to structural deformation or optical distortion.

[0036] The support frame 23 adopts a truss-type support frame.

[0037] The support frame 23, the frame of the primary mirror 21, and the frame of the secondary mirror 22 are all made of Invar alloy with an ultra-low coefficient of thermal expansion. The fixing structure with an ultra-low coefficient of thermal expansion can lock the relative position of the primary mirror 21 and the secondary mirror 22 over a wide temperature range, thereby effectively suppressing the thermal deformation of the first-stage beam reducer 2.

[0038] Furthermore, the primary beam reducer 2 also includes a six-dimensional adjustment mechanism 25, through which the secondary mirror 22 is fixed to the support frame 23.

[0039] Among them, the six-dimensional adjustment mechanism 25 is used to make precise adjustments to the secondary mirror 22 of the primary beam reducer 2 in all six degrees of freedom, including position adjustment and angle adjustment.

[0040] Specifically, such as Figure 3 As shown, in this embodiment, the six-dimensional adjustment mechanism 25 includes a translation adjustment mechanism and an angle adjustment mechanism.

[0041] The translation adjustment mechanism includes a second adjustment plate 254 and a first adjustment plate 253 stacked on the outer cylindrical surface of the secondary mirror frame. The second adjustment plate 254 has a horizontally elongated groove on the side near the outer cylindrical surface of the secondary mirror frame, and is slidably connected to the outer cylindrical surface of the secondary mirror frame via this groove. The first adjustment plate 253 has a vertically elongated groove on the side near the second adjustment plate 254, and is slidably connected to the second adjustment plate 254 via this groove. By sliding the first adjustment plate 253 and the second adjustment plate 254 and locking their positions, the translation amount of the secondary mirror 22 can be adjusted in multiple dimensions.

[0042] The angle adjustment mechanism includes multiple arc-shaped slots 251 on the secondary mirror frame flange. Screws pass through the arc-shaped slots 251 to fix the secondary mirror frame flange to the side of the first adjustment plate 253 away from the second adjustment plate 254. Different sizes of shim sets 252 can be placed between the arc-shaped slots 251 and the first adjustment plate 253. The pitch and roll angles of the secondary mirror 22 can be adjusted by adjusting the thickness and setting position of the shim sets 252 at different positions.

[0043] In this embodiment, the core of assembling and adjusting the secondary mirror 22 of the primary beam reducer is to use the wavefront aberration of the interferometer detection system as a feedback signal to precisely guide the operation of the six-dimensional adjustment mechanism 25 (angle adjustment mechanism and translation adjustment mechanism) to form a closed-loop process.

[0044] Specifically, in step 101, with the position of the primary mirror 21 as a reference, the secondary mirror 22 is initially installed on the support frame 23 through the arc-shaped slot 251 on the secondary mirror frame flange, and a shim set 252 of initial thickness is inserted between the arc-shaped slot 251 and the first adjustment plate 253, and then the screws are pre-tightened.

[0045] Step 102: Input a standard collimated beam into the testing device, and use an interferometer to detect the outgoing wavefront after passing through the first-stage beam shrinker 2 to obtain the wavefront aberration map of the optomechanical system.

[0046] Step 103: Calculate the required pitch and roll angle corrections for the secondary mirror 22 based on the wavefront aberration diagram, and achieve fine-tuning of the angle of the secondary mirror 22 by changing the thickness of the corresponding shims in the shim set 252.

[0047] Specifically, the aberration components (such as coma and astigmatism) of the wavefront aberration map have a clear correspondence with the angular deviation of the secondary mirror 22. Based on the calculated angular correction amount, it can be determined which arc-shaped slot 251 on the secondary mirror frame flange should be replaced with a gasket and the thickness of the gasket to be replaced. After replacing with a more precise gasket set 252, the screw at the arc-shaped slot 251 is tightened, and wavefront detection is performed again.

[0048] After the angle error meets the preset error threshold requirement, the residual wavefront aberration may still originate from the eccentricity or defocus of the secondary mirror 22. At this time, the translation adjustment mechanism is operated, and wavefront detection is performed again.

[0049] Step 104: Based on the wavefront detection results, determine and adjust the positions of the first adjustment plate 253 and the second adjustment plate 254 fitted outside the frame of the secondary mirror 22 to correct the translational deviation of the secondary mirror 22 in multiple dimensions.

[0050] Step 105: Repeat steps 102 to 104 to perform multiple tests and adjustments until the wavefront aberration of the optomechanical system meets the preset tolerance. Finally, completely tighten all the fasteners of the adjustment mechanisms.

[0051] Fasteners for all adjustment mechanisms include screws for securing the arc-shaped slot 251, and fastening screws for locking the positions of the first adjustment plate 253 and the second adjustment plate 254.

[0052] The adjustment of the positions of the first adjustment plate 253 and the second adjustment plate 254 is achieved by first loosening the fastening screws of the corresponding adjustment plates, then using a micrometer or dial indicator to push the adjustment plates to the target positions, and finally tightening the fastening screws again.

[0053] This assembly and adjustment method converts the mechanical displacement, which is difficult to measure directly, into an optical wavefront signal that can be precisely quantified for control, thereby improving the assembly and adjustment accuracy, repeatability, and efficiency.

[0054] Furthermore, the secondary beam reducer 3 includes a lens barrel 31 and an optical lens group 32 disposed within the lens barrel 31; the lens barrel 31 is fixed inside the housing 1 by a bracket 33, and the optical lens group 32 is used to reduce the aperture of the parallel beam output from the primary beam reducer 2.

[0055] Each lens in the optical lens group 32 has an independent mechanical centering structure and is flexibly connected to the lens barrel 31 by circumferential glue injection. The lens barrel 31 is provided with a ventilation hole 34.

[0056] Specifically, each lens has an independent mechanical centering structure, which can individually calibrate the optical axis of each lens with the mechanical axis of the lens barrel 31, ensuring high coaxiality. This effectively avoids the cumulative assembly error of the optical lens group 32, thereby reducing aberrations and energy loss after beam contraction and improving the uniformity and quality of the contracted beam spot. The independent mechanical centering structure also allows for the repositioning or fine-tuning of individual lenses within the optical lens group 32, reducing assembly and adjustment difficulty.

[0057] Compared with rigid connection methods, the present invention uses circumferential glue injection to achieve flexible connection between the lens and the lens barrel 31. The glue layer can compensate for the difference in the coefficient of linear expansion between the lens material (glass or crystal) and the metal material of the lens barrel 31, avoiding internal stress or lens deformation when the temperature changes. The glue layer can also absorb external mechanical vibration or impact, reduce the risk of lens displacement or breakage, and improve the reliability of the overall device in environments such as transportation and platform vibration. Circumferential glue injection can also make the lens circumference uniformly stressed, avoiding optical surface distortion caused by local stress concentration.

[0058] Ventilation holes 34 are provided on the lens barrel 31 to keep the internal cavity in balance with the external air pressure, prevent the internal gas from expanding / contracting and generating positive and negative pressure due to temperature changes (such as the lens barrel 31 heating up when laser is emitted), and avoid the lens or the coating layer from bearing additional pressure.

[0059] In this embodiment, the lens barrel 31 of the secondary beam reducer 3 is connected to the housing 1 structure through a bracket 33 with a straight groove, and the overall sway angle of the secondary beam reducer 3 can be finely adjusted by replacing the shims of different thicknesses.

[0060] Furthermore, the spectroscopic testing assembly includes a first spectroscopic element 41, a second spectroscopic element 42, a third spectroscopic element 43, a first camera 51, a far-field imaging lens 61, a second camera 62, a high-speed photodetector 71, and a fiber optic spectrometer 81.

[0061] The first beam splitter 41 is disposed at the output end of the secondary beam reducer 3 and is used to split the main optical beam. The second beam splitter 42 is disposed in the transmission optical path of the first beam splitter 41, and the third beam splitter 43 is disposed in the reflection optical path of the first beam splitter 41.

[0062] The first camera 51 is set on the reflected light path of the third beam splitter 43, and together with the reflected light path of the first beam splitter 41 and the reflected light path of the third beam splitter 43, it forms a near-field spot acquisition branch 5.

[0063] The far-field imaging lens 61 is set in the transmission light path of the second beam splitter 42. The second camera 62 is connected to the far-field imaging lens 61, and together with the transmission light path of the first beam splitter 41 and the transmission light path of the second beam splitter 42, they form a beam pointing test branch 6.

[0064] The high-speed photodetector 71 is set in the reflected light path of the second beam splitter 42, and together with the transmitted light path of the first beam splitter 41 and the reflected light path of the second beam splitter 42, it forms a time characteristic measurement branch 7.

[0065] The fiber optic spectrometer 81 is set on the transmission optical path of the third beam splitter 43, and together with the reflection optical path of the first beam splitter 41 and the transmission optical path of the third beam splitter 43, it forms a spectral characteristic acquisition branch 8.

[0066] Specifically, this invention utilizes the transmission and reflection optical paths of the first beam splitter 41, the second beam splitter 42, and the third beam splitter 43 to divide the main optical beam into four independent branches. This allows for the simultaneous acquisition of the laser beam's near-field spot, beam direction, time waveform, and spectral characteristics without the need for switching optical paths or repeating experiments, significantly improving the measurement efficiency and data consistency of the laser parameter testing device. Furthermore, each test branch is relatively independent, allowing for the individual replacement or upgrading of its test components (such as the first camera 51, the second camera 62, the high-speed photodetector 71, and the fiber optic spectrometer 81) without affecting the optical path collimation of other branches, thus enhancing the flexibility and maintainability of the testing device.

[0067] The first beam splitter 41 divides the main optical beam into transmission and reflection paths. Then, the second and third beam splitters 42 and 43 further subdivide the transmission and reflection paths after beam splitting by the first beam splitter 41. Each test branch receives only the required light intensity, avoiding energy waste. Furthermore, the test branches are spatially separated, and the use of combinations of transmission or reflection paths from different beam splitters 4 effectively prevents crosstalk between different measurement functions, ensuring the independence of each test branch's measurement. Through this cascaded beam splitting method, four measurement functions are integrated within the limited space of the housing 1, eliminating the need for multiple independent optical probes or complex beam switching mechanisms, effectively reducing the size and cost of the testing device.

[0068] The near-field spot acquisition branch 5 can independently adjust the reflection splitting ratio to avoid damage to the first camera 51 from strong light; the beam pointing test branch 6 uses a far-field imaging lens 61 in conjunction with a second camera 62 to amplify angular deviations and improve pointing accuracy; the high-speed photodetector 71 is placed on the reflected light path of the second beam splitter 42, enabling rapid response to time waveforms; the fiber optic spectrometer 81 is placed on the transmitted light path of the third beam splitter 43, enabling stable spectral acquisition. The near-field spot acquisition branch 5 and the beam pointing test branch 6 can jointly analyze beam quality, while the time characteristic measurement branch 7 and the spectral characteristic acquisition branch 8 can simultaneously monitor the time-frequency characteristics of pulsed lasers, providing complete parameters for laser debugging or application.

[0069] Furthermore, the working surfaces of the first beam splitter 41, the second beam splitter 42, and the third beam splitter 43 are all provided with wedge angles to suppress optical feedback and stray light, thereby improving the test signal-to-noise ratio of each test branch.

[0070] In addition, all the transmissive optical elements in the spectrophotometer are coated with a broadband antireflection film with extremely low reflectivity in the laser operating band to suppress stray light at the source.

[0071] Attenuation mirror groups are provided in the near-field spot acquisition branch 5, the beam pointing test branch 6, the time characteristic measurement branch 7, and the spectral characteristic acquisition branch 8.

[0072] Specifically, the attenuation mirror group is used to finely control the light intensity to adapt to different test elements. A reasonable setting of the attenuation amount of the attenuation mirror group can maximize the measurement dynamic range, accuracy and repeatability of each test branch while protecting the test elements.

[0073] Furthermore, the attenuation lens assembly includes a quick-replacement attenuation element 9. The attenuation element 9 is installed at an angle of 3~5° to the optical axis and is installed in the lens frame of the attenuation lens assembly by means of a pressure ring and circumferential glue injection.

[0074] Specifically, an attenuator installation angle of 3-5° effectively eliminates interference and avoids backlighting while having minimal impact on beam quality, making engineering implementation simpler.

[0075] Meanwhile, the target surface of the high-speed photodetector 71 can be adjusted to a slightly defocused state to diffuse residual uniform background noise.

[0076] Furthermore, the housing 1 is equipped with a heat insulation plate 14 and a stray light shielding cylinder 15.

[0077] The stray light shielding tube 15 is located outside the optical path of the secondary beam shrinker 3.

[0078] Specifically, a stray light shielding tube 15 is set between the optical lens groups 32 of the secondary beam reducer 3. This can systematically eliminate non-imaging stray light generated inside the secondary beam reducer 3 by combining geometric interception and surface absorption, thereby ensuring the purity of the output beam and the system imaging quality.

[0079] The heat insulation plate 14 is disposed around the first camera 51, the second camera 62 and the fiber optic spectrometer 81, and together with the stray light shielding cylinder 15, forms a physical isolation zone for the heat source.

[0080] Furthermore, the enclosure 1 includes a base plate 11 and side plates 12 disposed on the outer periphery of the base plate 11; the enclosure 1 is also provided with a partition 13 for dividing the enclosure 1 into the main optical path cavity and the electrical compartment, and the heat control equipment of the test device is located in the electrical compartment.

[0081] The heat control equipment includes the power supply of the testing device, the industrial computer, and the camera driver.

[0082] The base plate 11 is made of titanium alloy, while the side plates 12 and partitions 13 are made of aluminum alloy.

[0083] The side panel 12 integrates a cooling fan 16 and an aviation connector panel 17. Specifically, as shown... Figure 4 As shown, the flight plug panel 17 is equipped with a main power switch 1701, a camera power switch 1702, a fan switch 1703, a main power socket 1704, and a network interface 1705.

[0084] In this embodiment, the enclosure 1 provides rigid mechanical support and a stable, sealed optical path environment for the testing device. The base plate 11 of the enclosure 1 is made of titanium alloy with high specific stiffness and moderate thermal conductivity, serving as the mounting reference and heat sink for the entire optomechanical system. The side plates 12 and internal partitions 13 of the enclosure 1 are made of lightweight aluminum alloy. The interior of the enclosure 1 is divided into a main optical path cavity and an electrical compartment by the partitions 13. The power supply, industrial computer, camera driver, and other heat-generating control equipment of the testing device are all located in the electrical compartment. Furthermore, the test data from each test branch is collected via cables and synchronously processed and displayed in the industrial computer. A heat insulation plate 14 and a stray light shielding cylinder 15 are installed inside the main optical path cavity. The heat insulation plate 14 is positioned between the heat-generating element area of ​​the test element in the spectrophotometer and the optical path. The stray light shielding cylinder 15 is formed by covering the outer periphery of the optical path of the secondary beam reducer 3 with an inner wall coated with black anodized or high-absorption coating. The heat insulation plate 14 and the stray light shielding cylinder 15 together constitute a physical isolation zone for the heat source, physically blocking the influence of heat radiation and air convection on the optical path. Multiple cooling fans 16 installed on the side plate 12 of the enclosure 1 constitute an active heat dissipation zone, which forces air cooling onto the side wall of the enclosure 1 to remove heat from inside the enclosure 1.

[0085] The structural design of the housing 1 of this invention, and the installation structure of the primary beam reducer 2 and the secondary beam reducer 3, have high rigidity and vibration resistance characteristics, making them suitable for various working conditions such as laboratories and the field. Furthermore, the modular attenuation lens group and the centralized control panel 17 design make it easier for users to operate, maintain, and expand the functions.

[0086] Furthermore, the main structure of the testing device of this invention adopts a lightweight frame design using aluminum alloy, resulting in a smaller overall device size and greatly improving the mobility and deployment flexibility of the testing device.

[0087] In this invention, firstly, the heat insulation plate 14 and the stray light shielding cylinder 15 work together to form a physical isolation zone for the heat source, thereby significantly reducing the parasitic heat load at the source.

[0088] Secondly, the Invar alloy support frame 23, the lens frame of the primary mirror 21, and the lens frame of the secondary mirror 22, the flexible fixation structure of the optical lens group 32 of the secondary beam reducer 3 and the lens barrel 31, and the heat-dissipating connection module 24 constitute a low-thermal-deformation support area for the optical elements. In other words, for unavoidable residual heat and environmental changes, the Invar alloy support frame 23 of the primary beam reducer 2 acts as a "thermal bridge" with high thermal conductivity and low thermal deformation, efficiently and uniformly conducting heat or environmental temperature changes to the entire frame of the test device, causing the optical lens group (primary mirror 21 and secondary mirror 22) to tend to an isothermal state, thereby fundamentally suppressing surface distortion caused by temperature gradients; and the support frame 23 and the base plate 11 of the housing 1 are connected by the heat-dissipating connection module 24 as a flexible connection hotspot, which decouples the deformation of the base plate 11 while transferring heat.

[0089] Finally, the cooling fan 16 and the heat dissipation bracket 33 of the high-speed photodetector 71 constitute an active heat dissipation zone. In other words, the titanium alloy base plate 11 serves as the "heat sink" of the entire test device, and the cooling fan 16 installed on the side plate 12 establishes a uniform low-temperature boundary environment by cooling the side plate 12 of the chamber, continuously and gently removing heat through the thermal path to maintain the dynamic thermal balance of the system.

[0090] The combination of the heat source physical isolation area, the optical element low thermal deformation support area, and the active heat dissipation area constitutes the full-link thermal management structure of the test device of this invention, thereby significantly suppressing the sensitivity of thermal deformation to ambient temperature and effectively ensuring the stability and accuracy of optical measurements.

[0091] In other words, the present invention employs a thermal management strategy that combines thermal isolation and active heat dissipation inside the housing 1 to ensure that the testing device can operate stably over a wide temperature range.

[0092] like Figure 5 As shown, in a second aspect, embodiments of the present invention also provide a large-aperture multi-parameter testing method based on dual-stage beam contraction, characterized in that the method, applied to any of the above-mentioned large-aperture multi-parameter testing devices based on dual-stage beam contraction, includes: Step 501: Introduce the large-aperture laser beam to be tested into the large-aperture multi-parameter testing device based on dual-stage beam contraction.

[0093] Step 502: The large-aperture laser beam to be tested is processed sequentially by the first-stage beam shrinker 2, the second-stage beam shrinker 3, and the beam splitting test component. Simultaneously, the near-field spot image of the near-field spot acquisition branch 5, the beam pointing angle of the beam pointing test branch 6, the time pulse waveform of the time characteristic measurement branch 7, and the spectral data of the spectral characteristic acquisition branch 8 are acquired.

[0094] Step 503: Process the synchronously acquired near-field spot image, beam pointing angle, time pulse waveform and spectral data, and display the multi-parameter measurement results.

[0095] In this embodiment, an inlet is provided on the side plate 12 of the housing 1 at the position corresponding to the primary mirror 21 of the first-stage beam shrinker 2. During actual testing, the testing device is placed on a stable platform, and its inlet is roughly aligned with the outlet of the laser device. Then, the main power supply of the testing device is turned on; the low-power guide light of the laser device is turned on, and the position of the testing device is finely adjusted so that the guide light passes completely through the center of the dual-stage beam shrinking system composed of the first-stage beam shrinker 2 and the second-stage beam shrinker 3; the test parameters are configured in conjunction with the control software, and the attenuation mirror group of each test branch is configured according to the laser power in the test parameters set in the control software. The laser is triggered to emit the large-aperture laser beam (test light) to be tested, and at the same time, the control software triggers the data acquisition function of all test branches.

[0096] The industrial control computer processes the synchronously acquired near-field spot images, beam pointing angle, time pulse waveforms, and spectral data. Specifically, this includes spot analysis, stability parameter calculation, pulse waveform feature extraction, and wavelength and spectral width analysis. All processing results (multi-parameter measurement results) are displayed in real time on a comprehensive interface.

[0097] After the test is completed, turn off the laser and the testing device.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A large-aperture multi-parameter testing device based on dual-stage beam contraction, characterized in that, The system includes a housing and an optomechanical system integrated within the housing in a sealed optical path environment; the optomechanical system includes a first-stage beam shortener, a second-stage beam shortener, and a beam splitting test assembly arranged sequentially along the optical path direction. The primary beam shrinker is an off-axis two-reflector structure, used for primary beam shrinking of incident large-aperture laser beams. The secondary beam shrinker is a transmission-type lens tube structure, used to perform secondary beam shrinking on the beam after primary beam shrinking and extend the exit pupil distance to obtain the main optical path beam. The beam splitting test assembly includes a beam splitting element and multiple test branches. The beam splitting element is used to synchronously split the main optical path beam into the multiple test branches. The multiple test branches include a near-field spot acquisition branch, a beam pointing test branch, a time characteristic measurement branch, and a spectral characteristic acquisition branch. The primary beam reducer includes a primary mirror, a secondary mirror, and a support frame. The support frame is fixed inside the housing via a heat-dissipating connection module. The secondary beam reducer includes a lens barrel and an optical lens group disposed within the lens barrel. The support frame, the lens frame of the primary mirror, and the lens frame of the secondary mirror are made of Invar alloy. The flexible fixation structure of the optical lens group and the lens barrel in the secondary beam reducer, along with the heat-dissipating connection module, constitute a low-thermal-deformation support area for the optical elements. The support frame is used to fix the position and angle of the primary mirror and the secondary mirror; the primary mirror is used to receive and converge the received large-aperture laser beam; the secondary mirror is located in the reflection optical path of the primary mirror and is used to reflect the beam converged by the primary mirror again and collimate it into a smaller diameter output beam. The primary beam shrinker also includes a six-dimensional adjustment mechanism, and the secondary mirror is fixed to the support frame through the six-dimensional adjustment mechanism. The lens barrel is fixed inside the housing by a bracket, and the optical lens group is used to reduce the aperture of the parallel beam output from the first-stage beam reducer. Each lens in the optical lens group has an independent mechanical centering structure and is flexibly connected to the lens barrel by circumferential glue injection; the lens barrel is provided with ventilation holes.

2. The large-aperture multi-parameter testing device based on dual-stage beam contraction according to claim 1, characterized in that, The spectral testing assembly includes a first spectral element, a second spectral element, a third spectral element, a first camera, a far-field imaging lens, a second camera, a high-speed photodetector, and a fiber optic spectrometer. The first beam splitter is disposed at the output end of the secondary beam reducer and is used to split the main optical beam. The second beam splitter is disposed in the transmission optical path of the first beam splitter, and the third beam splitter is disposed in the reflection optical path of the first beam splitter. The first camera is positioned on the reflected light path of the third beam splitter, and together with the reflected light path of the first beam splitter and the reflected light path of the third beam splitter, they form the near-field spot acquisition branch. The far-field imaging lens is disposed on the transmission light path of the second beam splitter, and the second camera is connected to the far-field imaging lens, forming the beam pointing test branch together with the transmission light path of the first beam splitter and the transmission light path of the second beam splitter. The high-speed photodetector is disposed on the reflected light path of the second beam splitter, and together with the transmitted light path of the first beam splitter and the reflected light path of the second beam splitter, it forms the time characteristic measurement branch. The fiber optic spectrometer is positioned on the transmission optical path of the third beam splitter, and together with the reflection optical path of the first beam splitter and the transmission optical path of the third beam splitter, it forms the spectral characteristic acquisition branch.

3. The large-aperture multi-parameter testing device based on dual-stage beam contraction according to claim 2, characterized in that, The working surfaces of the first beam splitter, the second beam splitter, and the third beam splitter are all provided with wedge angles; The near-field spot acquisition branch, the beam pointing test branch, the time characteristic measurement branch, and the spectral characteristic acquisition branch are all equipped with attenuation mirror groups.

4. The large-aperture multi-parameter testing device based on dual-stage beam contraction according to claim 3, characterized in that, The attenuation lens assembly includes an attenuation plate, which is installed at an angle of 3 to 5 degrees to the optical axis.

5. The large-aperture multi-parameter testing device based on dual-stage beam contraction according to claim 2, characterized in that, The box is equipped with a heat insulation board and a stray light shielding cylinder; The stray light shielding tube is disposed around the optical path of the secondary beam shrinker; The heat insulation plate is disposed on the outer periphery of the first camera, the second camera, and the fiber optic spectrometer, and together with the stray light shielding cylinder, forms a physical isolation zone for the heat source.

6. The large-aperture multi-parameter testing device based on dual-stage beam contraction according to claim 5, characterized in that, The enclosure includes a base plate and side plates disposed on the outer periphery of the base plate; the enclosure is also provided with a partition for dividing the enclosure into a main optical path cavity and an electrical compartment, and the heat control equipment of the test device is located in the electrical compartment; The base plate is made of titanium alloy, and the side plates and the partition are made of aluminum alloy. The side panel integrates a cooling fan and an aviation plug panel.

7. A large-aperture multi-parameter testing method based on dual-stage beam contraction, characterized in that, The method, applied to any one of the claims 1 to 6, for a large-aperture multi-parameter testing device based on dual-stage beam contraction, comprises: A large-aperture laser beam to be tested is introduced into the large-aperture multi-parameter testing device based on dual-stage beam contraction. The large-aperture laser beam under test is processed sequentially by a first-stage beam shrinker, a second-stage beam shrinker, and a beam splitting test component. Simultaneously, the near-field spot image of the near-field spot acquisition branch, the beam pointing angle of the beam pointing test branch, the time pulse waveform of the time characteristic measurement branch, and the spectral data of the spectral characteristic acquisition branch are acquired. The synchronously acquired near-field spot image, beam pointing angle, time pulse waveform, and spectral data are processed, and the multi-parameter measurement results are displayed.

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