Modular off-axis optical probing system and method

Abstract

The application discloses a modular off-axis optical detection system and method, relates to the technical field of optical detection and measurement, and can solve the technical problems of difficult assembly and adjustment, poor environmental adaptability and inconvenient maintenance of a traditional off-axis optical system. The system comprises a system base plate, an off-axis main expansion module, a beam splitter group, a measurement mirror group module and an imaging mirror group module. The off-axis main expansion module is used as a front common light path of the optical detection system and is used for receiving and shrinking a incident light beam. The optical axis of the off-axis main expansion module is the only assembly and adjustment reference axis of the system. The beam splitter group is arranged in the exit light path of the off-axis main expansion module, is used for splitting the exit light beam of the off-axis main expansion module into a first light beam and a second light beam, and is used for guiding the first light beam and the second light beam to the measurement mirror group module and the imaging mirror group module respectively. The measurement mirror group module is used for performing optical parameter measurement on the first light beam. The imaging mirror group module is used for receiving the second light beam and performing high-resolution imaging and information extraction on a target.

Description

Technical Field

[0001] This application relates to the field of optical detection and measurement technology, and in particular to a modular off-axis optical detection system and method. Background Technology

[0002] High-precision optical detection systems are core equipment in modern remote sensing, astronomical observation, laser communication, and precision industrial measurement. To achieve higher image resolution, better contrast, and a larger usable aperture, and to avoid the impact of central obstruction on image quality, advanced optical detection systems commonly employ off-axis optical system designs. Off-axis optical systems, by offsetting the beam or optical elements outside the system's mechanical axis of symmetry, effectively eliminate the central obstruction problem caused by secondary mirrors and their support structures in traditional coaxial reflective systems, thereby enabling the acquisition of high-quality beams and images with near-diffraction-limit-free degradation.

[0003] However, while off-axis optical systems offer performance advantages, their inherent asymmetry also introduces a series of severe technical challenges. First, the assembly and adjustment process is extremely complex and difficult. Due to the asymmetry of the optical path, the spatial orientation tolerances of each optical element are extremely stringent, and there is a strong coupling relationship between them. Traditional assembly and adjustment methods heavily rely on the operator's experience, achieving optical path alignment and aberration correction through repeated trial and error and manual fine-tuning. This is not only time-consuming and labor-intensive, but also inefficient, and makes it difficult to guarantee the consistency and reliability of product performance. Second, the system has poor environmental adaptability, especially temperature adaptability. Off-axis optical systems are extremely sensitive to structural stability. When operating over a wide temperature range, the different materials used in the system will experience uneven thermal deformation due to differences in their coefficients of thermal expansion. This deformation is directly transmitted to the optical elements, causing surface distortion and relative position drift, resulting in significant degradation of optical performance. Third, the system lacks maintainability and upgradeability. Traditional off-axis systems are mostly integrated or quasi-integrated designs, with tightly coupled optical path components lacking clear physical and functional interfaces. If a component in the system fails or needs performance upgrades, it often requires a large-scale disassembly and reassembly of the entire system, resulting in high maintenance costs and a long cycle.

[0004] In summary, existing off-axis optical detection systems face significant contradictions and bottlenecks in three key dimensions: assembly and adjustment accuracy and efficiency, stability in wide-temperature environments, and modular maintenance and upgrades. Therefore, there is a pressing need for a modular off-axis optical detection system with a reasonable structure, convenient assembly and adjustment, and strong environmental adaptability, along with a corresponding high-precision, repeatable assembly and adjustment method. Summary of the Invention

[0005] This application provides a modular off-axis optical detection system and method, which can solve the technical problems of difficult assembly and adjustment, poor environmental adaptability and inconvenient maintenance of traditional off-axis optical systems.

[0006] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides a modular off-axis optical detection system, the system comprising: a system base plate, and an off-axis main expansion module, a beam splitter group, a measurement lens group module, and an imaging lens group module mounted on the system base plate; The off-axis main expansion module serves as the front common optical path of the optical detection system, used to receive and narrow the incident beam. The optical axis of the off-axis main expansion module is the only assembly reference axis of the system. The beam splitter group is disposed in the output optical path of the off-axis main expansion module, and is used to split the output beam of the off-axis main expansion module into a first beam and a second beam, and then guide the first beam and the second beam to the measuring mirror group module and the imaging mirror group module respectively. The measuring mirror module is used to measure the optical parameters of the first beam; The imaging lens module is used to receive the second beam and perform high-resolution imaging and information extraction on the target.

[0007] This application establishes the optical axis of the off-axis master expansion module as the sole assembly and adjustment reference axis for the entire system, thus realizing a paradigm shift from "multi-reference collaboration" to "single-reference traceability" in assembly and adjustment. Each functional module is designed and assembled with this single reference axis as a reference, fundamentally eliminating the reference deviation coupling problem between optical paths. This allows the assembly and adjustment of each module to be performed independently, and ultimately, system integration can be completed by simply connecting the optical paths with this reference axis as a reference, significantly improving assembly and adjustment efficiency and consistency.

[0008] In one embodiment, the off-axis primary expansion module includes: an off-axis primary expansion base plate, and an off-axis primary expansion objective lens, an off-axis primary expansion folding mirror, an off-axis primary expansion reflecting mirror, and an off-axis primary expansion secondary mirror mounted on the off-axis primary expansion base plate; The off-axis master base plate is made of Invar steel. Invar steel has an extremely low coefficient of thermal expansion, which can suppress the disturbance of temperature fluctuations on the position and orientation of the reference axis to the greatest extent, ensuring that the reference axis maintains high accuracy and high repeatability across the entire operating temperature range, and providing a stable optomechanical reference for the entire system.

[0009] In one embodiment, the system base plate is made of aluminum alloy. The system base plate is connected to the off-axis main expansion base plate via an elastic connector, which isolates the transfer of thermal deformation between the system base plate and the off-axis main expansion base plate. This elastic connector employs a flexible hinge structure, absorbing the relative displacement caused by the difference in thermal expansion coefficients between the system base plate and the off-axis main expansion base plate through its controllable elastic micro-deformation, thus physically cutting off the transmission path of thermal deformation to the core reference optical path. This solution is a passive, heatless design, requiring no additional power consumption or active control, and features zero response latency and high reliability.

[0010] In one embodiment, a centering structure is provided inside the barrel of both the measuring mirror module and the imaging mirror module. The centering structure includes a centering frame and a lens; The lens is fixed to the centering frame by a pressure ring and glue injection. A replaceable trimming ring is provided between the centering frame and the lens barrel for adjusting the axial spacing of the lens.

[0011] In one embodiment, the image plane position of the imaging lens module is equipped with a temperature-compensated detector, which has an electrically controlled shift focusing function to compensate for image plane drift caused by temperature changes. This temperature-compensated detector, through a focusing mechanism integrated at the rear of the lens barrel, constitutes an active thermal compensation subsystem. When changes in ambient temperature cause image plane position drift in the optical system, the detector is driven to move slightly along the optical axis, allowing its photosensitive surface to precisely align with the drifted image plane, thereby restoring image sharpness in real time. This active thermal compensation works synergistically with the aforementioned passive anechoic structure; the passive structure suppresses most thermally induced deformation, and the active detector corrects residual image plane drift, jointly ensuring that the system maintains near-diffraction-limited imaging quality over a wide temperature range.

[0012] In one embodiment, both the measuring mirror module and the imaging mirror module are provided with attenuation mirrors in their optical paths; The attenuation mirror assembly includes multiple attenuators arranged at a preset angle to the optical axis, and these attenuators are arranged in a non-coplanar Z-shaped configuration in the optical path to suppress stray light. This configuration causes incident stray light to deviate from the main optical path after multiple reflections between the attenuators, preventing it from reaching the detector, while the main beam is transmitted along the designed path. This achieves efficient suppression of stray light within the system, significantly improving the signal-to-noise ratio of measurement and imaging.

[0013] In one embodiment, the system base plate is provided with multiple adjustable feet; The adjustable foot includes a foot base, a first screw, a second screw, and a third screw; The second screw has a reverse thread. Rotating the second screw can cause the first screw and the third screw to move synchronously toward or away from each other to adjust the system height.

[0014] A second aspect of this application provides a method for assembling and adjusting a modular off-axis optical detection system. This method is used to assemble and adjust the modular off-axis optical detection system described in the first aspect of this application. The method includes: The optical axis of the off-axis main expansion module is used as the assembly and adjustment reference axis for the entire system. After internal optical path adjustments to the off-axis main expansion module, measuring mirror group module, and imaging mirror group module respectively, the off-axis main expansion module, beam splitter group, measuring mirror group module, and imaging mirror group module are installed on the system base plate. Based on the assembly reference axis, adjust the positions and orientations of the beam splitter group, the measurement lens group module, and the imaging lens group module to complete the optical path docking and system calibration.

[0015] In one embodiment, internal optical path adjustment of the off-axis main expansion module includes: The interferometer is placed at the focal point of the off-axis main expansion objective, and a plane mirror is placed at the light outlet of the off-axis main expansion module. The attitude of the plane mirror is adjusted to collimate the light beam emitted from the off-axis main expansion module and establish an initial coarse adjustment reference. Keeping the interferometer in its current position, the first theodolite is used to aim at the collimated beam emitted from the interferometer, and the optical axis of the collimated beam is extracted as the reference optical axis for subsequent assembly and adjustment. A second theodolite is set at a predetermined position in the direction of the outgoing light of the off-axis primary expander mirror. The two theodolites are aimed at each other to establish the outgoing light angle reference required for the installation of the off-axis primary expander mirror and the off-axis primary expander mirror. The off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror are installed in sequence. The attitude of the off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror is adjusted so that the collimated beam emitted by the first theodolite is reflected by the off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror in sequence and then enters the second theodolite, and the autocollimated image coincides with the crosshairs of the theodolite eyepiece. Remove the first and second theodolites, install an off-axis primary and secondary mirror, place an interferometer at a predetermined position on the light-emitting side of the off-axis primary and secondary mirror, so that the reflected beam of the plane mirror interferes with the emitted beam of the interferometer; using the system wave aberration as the evaluation function, adjust the attitude of the off-axis primary and secondary mirror until the root mean square value and peak-valley value of the wave aberration simultaneously reach the preset optical design index.

[0016] In one embodiment, internal optical path adjustment of the measuring mirror module and the imaging mirror module includes: A through-hole fixture is installed on the barrels of the measuring lens module and the imaging lens module respectively. The reference optical axes of the measuring lens module and the imaging lens module are led out through a theodolite. The through-hole fixture is used to establish a transferable correspondence between the mechanical axis of the lens barrel and the optical reference. Adjust the positions of the barrels of the measuring mirror module and the imaging mirror module respectively, so that the crosshairs of the through-hole fixture coincide with the crosshairs of the corresponding theodolite eyepiece; Remove the through-hole fixture and install the measuring lens module and the optical lens groups inside the imaging lens module in sequence.

[0017] The beneficial effects of the technical solutions provided in this application include at least the following: This application provides a modular off-axis optical detection system, comprising: a system base plate, and an off-axis main expansion module, a beam splitter group, a measurement lens group module, and an imaging lens group module mounted on the system base plate; the optical axis of the off-axis main expansion module is the sole assembly and adjustment reference axis of the system. Compared with existing integrated off-axis optical systems, the modular off-axis optical detection system provided by this application adopts a "one-axis, multiple-path" modular architecture, decomposing the complex system into functionally independent modules with clearly defined interfaces, supporting parallel development, independent assembly and testing, and greatly improving production efficiency, maintainability, and system upgrade flexibility. Furthermore, this application combines passive thermal compensation using an "Invar main expansion module + flexible connector" with an active thermal compensation subsystem for the imaging surface "electrically focused detector," forming a complete systemic thermal solution that ensures the system's extreme stability over a wide temperature range. This application also employs an integrated centering structure of "centering lens frame + circumferential glue injection + trimming ring," fundamentally ensuring lens coaxiality, and using the trimming ring to achieve precise control of lens spacing and system aberrations, reducing assembly and adjustment difficulty. Furthermore, this application employs a non-coplanar Z-shaped attenuation mirror group, which effectively suppresses stray light within the system through the physical mechanism of multiple reflections causing stray light to be off-axis, thus significantly improving the signal-to-noise ratio of measurement and imaging. Attached Figure Description

[0018] Figure 1 A schematic diagram of the optical path principle of a modular off-axis optical detection system provided in this application embodiment; Figure 2 A schematic diagram of a modular off-axis optical detection system structure provided in this application embodiment. Figure 1 ; Figure 3 A schematic diagram of a modular off-axis optical detection system structure provided in this application embodiment. Figure 2 ; Figure 4 A three-dimensional structural schematic diagram of an elastic connector provided in an embodiment of this application; Figure 5 This is a schematic diagram of a centering structure in an imaging lens module provided in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of a foot base provided in an embodiment of this application; Figure 7 A flowchart illustrating the assembly and adjustment method of a modular off-axis optical detection system provided in this application embodiment.

[0019] Figure label: 1-Off-axis main expansion module; 2-Beam splitter group; 3-Measuring mirror group module; 4-Imaging mirror group module; 5-System base plate; 6-Elastic connector; 7-Centering structure; 8-Adjustable feet; 9-Interferometer; 10-Plane mirror; 101 - Off-axis primary expander base plate; 102 - Off-axis primary expander objective lens; 103 - Off-axis primary expander folding mirror; 104 - Off-axis primary expander reflecting mirror; 105 - Off-axis primary expander secondary mirror; 71-Centering frame; 72-Lens; 73-Pressure ring; 74-Trimming ring; 801-Base; 802-First screw; 803-Second screw; 804-Third screw; 805-Limiting block. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] 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.

[0022] High-precision optical detection systems are core equipment in modern remote sensing, astronomical observation, laser communication, and precision industrial measurement. To achieve higher image resolution, better contrast, and a larger usable aperture, and to avoid the impact of central obstruction on image quality, advanced optical detection systems generally employ off-axis optical system designs. These systems, by offsetting the beam or optical elements outside the system's mechanical axis of symmetry, effectively eliminate the central obstruction problem caused by secondary mirrors and their support structures in traditional coaxial reflective systems, thereby enabling the acquisition of high-quality beams and images with near-diffraction-limit-free degradation.

[0023] However, while off-axis optical systems offer performance advantages, their inherent asymmetric characteristics also introduce a series of severe technical challenges, mainly in the following aspects: First, the system assembly and adjustment process is extremely complex and difficult. Due to the asymmetry of the optical path, the spatial pose (including three-dimensional coordinates and two-dimensional angles) tolerances of each optical component (such as off-axis objectives, off-axis mirrors, and folding mirrors) are extremely stringent, and there are strong coupling relationships between them. Traditional assembly and adjustment methods rely heavily on the operator's personal experience and "feel," requiring repeated trial and error and manual fine-tuning to achieve optical path alignment and aberration correction. This process is not only time-consuming and labor-intensive, resulting in low production efficiency, but also makes it difficult to guarantee the consistency and reliability of product performance, severely restricting the large-scale production and application of off-axis optical systems.

[0024] Secondly, environmental adaptability, especially temperature adaptability, is poor. Off-axis optical systems are extremely sensitive to structural stability. When operating over a wide temperature range (e.g., -40°C to +60°C), the different material components of the system (e.g., metal structural parts and glass optical elements) will experience uneven thermal deformation due to differences in their coefficients of thermal expansion. This deformation is directly transmitted to the precisely assembled optical elements, causing surface distortion and relative position drift, thus introducing non-negligible wavefront aberrations and image plane defocus, resulting in a significant degradation of the system's optical performance. Traditional integrated or rigid connection designs cannot fundamentally isolate and compensate for this thermally induced deformation, making it difficult for the system to operate stably in environments with drastic temperature changes, such as in the field or space.

[0025] Furthermore, the system lacks maintainability and upgradeability. Traditional off-axis systems are mostly integrated or quasi-integrated designs, with tightly coupled optical components and a lack of clear physical and functional interfaces. Once a component in the system fails or requires performance upgrades (such as replacing the detector), it often necessitates a large-scale disassembly and reassembly of the entire system, resulting in high maintenance costs, lengthy cycles, and the risk of performance degradation due to secondary reassembly. This cannot meet the demands of modern high-end equipment for high reliability, long lifespan, and rapid response to technological iterations.

[0026] In summary, existing off-axis optical detection systems face significant contradictions and bottlenecks in three key dimensions: assembly and adjustment accuracy and efficiency, stability in wide-temperature environments, and modular maintenance and upgrades. Therefore, there is an urgent need in this field for an innovative system architecture and engineering methodology that can systematically solve the aforementioned problems while maintaining the high-performance advantages of off-axis optics, designing a structurally sound, conveniently assembled and adjusted, environmentally adaptable, and easily maintained off-axis optical detection system, along with a corresponding high-precision, repeatable assembly and adjustment method.

[0027] To address the aforementioned problems, this application provides a modular off-axis optical detection system, such as... Figures 1-3 As shown, the system includes: a system base plate 5, and an off-axis main expansion module 1, a beam splitter group 2, a measurement lens group module 3, and an imaging lens group module 4 mounted on the system base plate 5; The off-axis main expansion module 1 serves as the front common optical path of the optical detection system, used to receive and narrow the incident beam. The optical axis of the off-axis main expansion module 1 is the only assembly reference axis of the system. The beam splitter group 2 is disposed in the output optical path of the off-axis main expansion module 1, and is used to split the output beam of the off-axis main expansion module 1 into a first beam and a second beam, and then guide the first beam and the second beam to the measuring mirror group module 3 and the imaging mirror group module 4 respectively. The measuring mirror module 3 is used to measure the optical parameters of the first beam; The imaging lens module 4 is used to receive the second beam and perform high-resolution imaging and information extraction on the target.

[0028] The off-axis main expansion module 1, beam splitter group 2, measurement lens group 3, and imaging lens group 4 can be independently mounted on the system base plate 5 via adjustable support structures. Measurement lens group 3 specifically measures optical parameters such as far-field distribution, pupil characteristics, and directivity of the first beam. Furthermore, imaging lens group 4 performs high-resolution imaging and information extraction on the second beam. Combined with dual-band imaging channels (first imaging channel and second imaging channel), it can simultaneously perform high-resolution imaging and information extraction on targets with different spectral characteristics, making it suitable for applications such as multispectral remote sensing, environmental monitoring, and special target identification.

[0029] The optical axis of the off-axis main expansion module 1 is defined as the sole assembly reference axis for the entire system. Furthermore, each module mounting position on the system base plate 5 is equipped with a precision mechanical positioning interface for rapid and repeatable positioning and installation of the modules. The measuring lens module 3 and the imaging lens module 4 are connected to the system base plate 5 via the precision mechanical positioning interface, achieving optomechanical docking with the reference axis as a reference. Further, the mounting bases of the off-axis main expansion folding mirror 103 and the off-axis main expansion reflecting mirror 104 are designed with arc-shaped grooves and / or straight grooves, which, in conjunction with adjusting shims, are used to achieve multi-dimensional attitude adjustment and locking of the lenses.

[0030] The modular off-axis optical detection system provided in this application establishes the optical axis of the off-axis main expansion module 1 as the sole assembly and adjustment reference axis for the entire system, realizing a paradigm shift from "multi-reference collaboration" to "single-reference traceability" in assembly and adjustment. This fundamentally eliminates the reference deviation coupling problem between optical paths, significantly improving assembly and adjustment efficiency and consistency. Furthermore, the physical boundaries of each functional module in this application are clear, and the interfaces are well-defined, allowing for independent completion of internal optical path assembly and performance testing at different workstations. This provides complete parallel operation capability and significantly shortens the system manufacturing cycle. Moreover, each module in this application achieves repeatable physical and optical positioning connections with the system base plate 5 through precision mechanical interfaces. If any module fails or requires performance upgrades, it can be directly and quickly replaced without requiring reassembly and adjustment of the entire system, greatly reducing the overall lifecycle maintenance cost.

[0031] Optionally, the off-axis main expansion module 1 includes: an off-axis main expansion base plate 101, and an off-axis main expansion objective lens 102, an off-axis main expansion folding mirror 103, an off-axis main expansion reflecting mirror 104, and an off-axis main expansion secondary mirror 105 mounted on the off-axis main expansion base plate 101; wherein, the off-axis main expansion base plate 101 is made of Invar steel.

[0032] Among them, the off-axis main expansion module 1 is the front core unit of the optical detection system of this application, and its specific composition includes: an off-axis main expansion base plate 101: which serves as the support base of the module and is made of Invar steel; an off-axis main expansion objective lens 102: used to receive and initially compress the incident beam; an off-axis main expansion folding mirror 103 and an off-axis main expansion reflecting mirror 104: used to change the direction of light path propagation to realize off-axis layout; and an off-axis main expansion secondary mirror 105: which works with the off-axis main expansion objective lens 102 to complete beam compression and aberration correction.

[0033] The aforementioned off-axis master base plate 101, made of Invar steel, can minimize the impact of temperature fluctuations on the position and orientation of the reference axis, ensuring that the reference axis maintains high precision and high reproducibility. Furthermore, the low expansion characteristics of Invar steel make it insensitive to temperature changes, effectively suppressing thermal deformation without additional power consumption or active control, making it a core means of achieving passive, calorimetric design in optical systems.

[0034] Optionally, the system base plate 5 is made of aluminum alloy; the system base plate 5 is connected to the off-axis main expansion base plate 101 through an elastic connector, and the elastic connector is used to isolate thermal deformation between the system base plate 5 and the off-axis main expansion base plate 101.

[0035] Among them, the elastic connector 6 is a flexible hinge structure, such as Figure 4This is a three-dimensional structural diagram of the elastic connector 6. It is understandable that there is a significant difference in the coefficient of thermal expansion between the system base plate 5 (aluminum alloy) and the off-axis main expansion base plate 101 (Invar). The elastic connector, through its controllable elastic micro-deformation, absorbs the relative displacement caused by temperature changes between the two, physically cutting off the transmission path of thermal deformation to the core reference optical path, requiring no power consumption, no control, and zero response delay.

[0036] Optionally, the measuring lens module 3 includes: a measuring base plate, and a measuring objective lens group, a measuring rotating mirror group 1, a measuring rotating mirror group 2, a measuring dichroic prism group 1, a measuring beam-shrinking eyepiece group, a measuring dichroic prism group 2, a measuring rotating mirror group 3, a measuring rotating mirror group 4, a first far-field measuring optical path detector and a second far-field measuring optical path detector mounted on the measuring base plate. The first far-field measurement optical path, consisting of the measuring objective lens group, the first measuring folding mirror group, the second measuring folding mirror group, the first measuring dichroic prism group, and the first far-field measurement optical path detector, is used for the transmission, reflection, and focusing of the laser beam. The second far-field measurement optical path, consisting of the measuring objective lens group, the first measuring folding mirror group, the second measuring folding mirror group, the first measuring dichroic prism group, the first measuring beam-shrinking eyepiece group, the second measuring dichroic prism group, the third measuring folding mirror group, the fourth measuring folding mirror group, and the second far-field measurement optical path detector, is located at the rear end of the beam measurement system and is used to receive the final emitted light. The far-field measurement optical path is used to collect the diffuse spot after the laser beam is focused, and the distribution of the diffuse spot is analyzed by software to obtain the far-field light intensity distribution of the beam, thereby monitoring the optical axis position of the system under test.

[0037] Furthermore, the measuring mirror module 3 can also integrate a high dynamic range detector, possessing excellent dynamic response characteristics. This high dynamic range detector adopts a multi-level gain architecture and is equipped with an adaptive exposure control circuit, enabling accurate measurement of drastically changing light intensity signals without saturation. The internal optical path of the measuring mirror module 3 is further optimized, integrating a first far-field measurement optical path and a second far-field measurement optical path, which can simultaneously complete optical axis pointing monitoring, multi-parameter far-field distribution measurement, and beam pupil characteristic analysis, meeting the comprehensive testing needs in complex optoelectronic environments.

[0038] Optionally, the imaging lens module 4 includes: an imaging base plate, and an imaging dichroic lens group, an imaging first lens group, an imaging folding lens group, an imaging second lens group, a first imaging optical path detector, and a second imaging optical path detector mounted on the imaging base plate. The imaging dichroic mirror group, the imaging first mirror group, and the first imaging optical path detector constitute the first imaging detection system; the imaging dichroic mirror group, the imaging folding mirror group, the imaging second mirror group, and the second imaging optical path detector constitute the second imaging detection system.

[0039] Optionally, the imaging lens module 4 can also integrate a dual-band imaging channel, including a first imaging channel and a second imaging channel. The two channels share a front imaging objective lens, achieve spectral separation through a dichroic separator, and are each equipped with a high-sensitivity detector for the corresponding spectral band. This design enables the system to simultaneously perform high-resolution imaging and information extraction on targets with different spectral characteristics, making it suitable for applications such as multispectral remote sensing, environmental monitoring, and special target identification.

[0040] Optionally, a centering structure 7 is provided inside the barrel of both the measuring mirror module 3 and the imaging mirror module 4, such as... Figure 5 The diagram shows a centering structure 7 in the imaging lens module 4. The centering structure 7 includes a centering frame 71 and a lens 72; the lens 72 is fixed in the centering frame 71 by a pressure ring 73 and glue injection; a replaceable trimming ring 74 is provided between the centering frame 71 and the lens barrel for adjusting the axial spacing of the lens 72.

[0041] Specifically, the axial spacing of the lens 72 is precisely adjusted by grinding or replacing trimming rings 74 of different thicknesses to compensate for machining and assembly tolerances and control system aberrations.

[0042] Optionally, the image plane position of the imaging lens module 4 is equipped with a temperature compensation detector, which has an electronically controlled moving focus function to compensate for image plane drift caused by temperature changes.

[0043] The temperature-compensated detector with electronically controlled moving focus function is implemented through an integrated focusing mechanism at the rear end of the imaging lens module 4; the focusing mechanism includes a precision linear guide, a drive motor and a position feedback unit, which constitute an active thermal compensation subsystem.

[0044] In its implementation, the temperature-compensated detector is integrated into the detector assembly at the image plane position of the imaging lens module 4, possessing an electrically controlled axial movement focusing function. When changes in ambient temperature cause the image plane position of the optical system to drift, the detector is driven to move slightly along the optical axis, allowing its photosensitive surface to precisely align with the drifted image plane, thereby restoring image sharpness in real time. Passive anechoic structures can suppress most thermally induced deformations, but cannot completely eliminate residual image plane drift. The temperature-compensated detector, through closed-loop active correction, performs secondary correction on the residual errors after passive compensation, enabling the system to maintain near-diffraction-limited imaging quality over a wide temperature range.

[0045] The temperature-compensated detector and the elastic connector together constitute an active-passive coordinated thermal compensation system, wherein the elastic connector is used to suppress thermally induced structural deformation, and the temperature-compensated detector is used to correct residual image plane drift.

[0046] Optionally, both the measuring mirror module 3 and the imaging mirror module 4 are provided with attenuation mirrors in the optical path; The attenuation mirror assembly includes multiple attenuation plates arranged at a preset angle to the optical axis, and the multiple attenuation plates are arranged in a non-coplanar Z-shaped layout in the optical path, so that stray light deviates from the main optical path after multiple reflections, thereby suppressing stray light in the system.

[0047] Optionally, the system base plate 5 is provided with multiple adjustable feet 8; each adjustable foot 8 includes a foot base 801, a first screw 802, a second screw 803, a third screw 804, and a limiting block 805; the second screw 803 has a reverse thread, and rotating the second screw 803 can cause the first screw 802 and the third screw 804 to move synchronously towards or away from each other, and simultaneously move closer or further apart, so as to quickly adjust the system height. Figure 6 The diagram shown is a structural schematic of the base 801.

[0048] This application provides a modular off-axis optical detection system. Compared with existing integrated off-axis optical systems, it adopts a "one-axis, multiple-path" modular architecture, decomposing the complex system into modules with independent functions and clear interfaces. It supports parallel development, independent assembly and testing, and greatly improves production efficiency, maintainability and system upgrade flexibility.

[0049] Furthermore, this application adopts a composite thermal management strategy, which combines the passive thermal compensation of the "Ingersoll main expansion module + elastic connector 6" with the active thermal compensation subsystem of the "electro-focusing detector" of the imaging surface to form a complete system thermal solution, ensuring the extreme stability of the system over a wide temperature range.

[0050] Secondly, this application adopts an integrated centering structure 7 consisting of "centering frame 71 + circumferential glue injection + trimming ring 74", which fundamentally ensures the coaxiality of lens 72 and achieves precise control of lens 72 spacing and system aberration through trimming ring 74, reducing the difficulty of assembly and adjustment and ensuring high performance.

[0051] Furthermore, this application employs a non-coplanar Z-shaped attenuation mirror group, which effectively suppresses stray light within the system through the physical mechanism of multiple reflections causing stray light to be off-axis, thus significantly improving the signal-to-noise ratio of measurement and imaging.

[0052] Based on the modular off-axis optical detection system provided in the embodiments of this application, the embodiments of this application also provide an assembly and adjustment method for the modular off-axis optical detection system described in this application, such as... Figure 7 As shown, the method includes the following steps: Step 101: Use the optical axis of the off-axis main expansion module 1 as the assembly and adjustment reference axis of the entire system; Step 102: After adjusting the internal optical path of the off-axis main expansion module 1, the measuring mirror group module 3 and the imaging mirror group module 4 respectively, install the off-axis main expansion module 1, the beam splitter group 2, the measuring mirror group module 3 and the imaging mirror group module 4 on the system base plate 5. Step 103: Based on the assembly reference axis, adjust the pose of the beam splitter group 2, the measurement lens group module 3, and the imaging lens group module 4 to complete the optical path docking and system calibration.

[0053] Optionally, step 102 above involves internal optical path adjustment of the off-axis main expansion module 1, including: The interferometer is placed at the focal point of the off-axis main expansion objective 102, and a plane mirror 10 is placed at the light outlet of the off-axis main expansion module 1. The attitude of the plane mirror 10 is adjusted to collimate the light beam emitted from the off-axis main expansion module 1 and establish an initial coarse adjustment reference. Keeping the position of the interferometer 9 unchanged, the collimated beam emitted from the interferometer 9 is aimed at by the first theodolite, and the optical axis of the collimated beam is extracted as the reference optical axis for subsequent assembly and adjustment; A second theodolite is set at a predetermined position in the direction of the emitted light of the off-axis primary expander mirror 104. The two theodolites are aimed at each other to establish the required emitted light angle reference for the installation of the off-axis primary expander mirror 103 and the off-axis primary expander mirror 104. The off-axis main expanding and folding mirror 103 and the off-axis main expanding and reflecting mirror 104 are installed in sequence. The attitudes of the off-axis main expanding and folding mirror 103 and the off-axis main expanding and reflecting mirror 104 are adjusted so that the collimated beam emitted by the first theodolite is reflected by the off-axis main expanding and folding mirror 103 and the off-axis main expanding and reflecting mirror 104 in sequence and then enters the second theodolite, and the autocollimated image coincides with the crosshairs of the theodolite eyepiece. Remove the first and second theodolites, install the off-axis primary and secondary magnifiers 105, place an interferometer at a predetermined position on the light-emitting side of the off-axis primary and secondary magnifiers 105, so that the reflected beam of the plane mirror 10 interferes with the emitted beam of the interferometer 9; using the system wavefront aberration as the evaluation function, adjust the attitude of the off-axis primary and secondary magnifiers 105 until the root mean square value and peak-valley value of the wavefront aberration simultaneously reach the preset optical design index.

[0054] Optionally, step 102 above involves internal optical path adjustment of the measuring mirror module 3 and the imaging mirror module 4, including: A through-hole fixture is installed on the barrel of the measuring mirror module 3 and the barrel of the imaging mirror module 4 respectively. The reference optical axes of the measuring mirror module 3 and the imaging mirror module 4 are led out through a theodolite. The through-hole fixture is used to establish a transferable correspondence between the mechanical axis of the barrel and the optical reference. Adjust the positions of the barrels of the measuring mirror module 3 and the imaging mirror module 4 respectively, so that the crosshairs of the through-hole fixture coincide with the crosshairs of the corresponding theodolite eyepiece. Remove the through-hole fixture and install the optical mirror groups inside the measuring mirror module 3 and the imaging mirror module 4 in sequence.

[0055] Optionally, the docking of the measuring mirror module 3 with the off-axis main expansion module 1 includes the following steps: The main optical axis of the off-axis main expansion module 1 is led out using a theodolite and used as a reference incident beam. A target with a crosshair reticle is temporarily set at the image detector installation position of the measuring mirror module 3. Adjust the position and orientation of the measuring mirror module 3 until the parallelism error between its outgoing beam and the reference incident beam meets the preset tolerance range, and complete the docking and installation of the measuring mirror module 3.

[0056] Optionally, the docking of the imaging lens module 4 with the off-axis main expansion module 1 includes the following steps: The main optical axis of the off-axis main expansion module 1 is led out using a theodolite and used as the system reference axis; An interferometer is mounted on the image side of the imaging mirror module 4 and guided by a theodolite to achieve initial alignment between the outgoing optical axis of the interferometer and the reference axis of the system. The interferometer is activated to collect wavelet aberrations of the entire system. The position and orientation of the imaging lens module 4 are iteratively adjusted based on the fact that the root mean square (RMS) and peak-to-valley (PV) values ​​of the wavelet aberrations simultaneously meet the design specifications, until the requirements are met, and the docking and installation of the imaging lens module 4 is completed.

[0057] Traditional off-axis optical systems employ a sequential assembly and adjustment mode, requiring subsequent modules to be assembled and adjusted only after the preceding optical path is fully in place. This results in strong coupling between the preceding and following processes, with rework at any stage causing overall system downtime. The modular off-axis optical detection system assembly and adjustment method provided in this application establishes the optical axis of the off-axis main expansion module 1 as the sole assembly and adjustment reference axis for the entire system. This allows the measurement lens module 3 and the imaging lens module 4 to independently complete precise assembly and performance testing of their internal optical paths at different workstations, completely detached from the final assembly area. The final system assembly only requires optical path interconnection between modules, significantly reducing the system assembly and adjustment cycle.

[0058] In addition, this application introduces an optomechanical reference transfer method of "through-the-center tooling + theodolite self-collimation" for the measuring mirror module 3 and the imaging mirror module 4, and specifies quantitative docking standards based on target parallelism criteria and interferometer wave aberration criteria for the system integration link, thereby improving the assembly and adjustment qualification rate.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A modular off-axis optical detection system, characterized in that, The system includes: a system base plate, and an off-axis main expansion module, a beam splitter group, a measurement lens group module and an imaging lens group module mounted on the system base plate; The off-axis main expansion module serves as the front common optical path of the optical detection system, used to receive and narrow the incident beam. The optical axis of the off-axis main expansion module is the only assembly reference axis of the system. The beam splitter group is disposed in the output optical path of the off-axis main expansion module, and is used to split the output beam of the off-axis main expansion module into a first beam and a second beam, and then guide the first beam and the second beam to the measuring mirror group module and the imaging mirror group module respectively. The measuring mirror module is used to measure the optical parameters of the first beam; The imaging lens module is used to receive the second beam and perform high-resolution imaging and information extraction on the target.

2. The system according to claim 1, characterized in that, The off-axis main expansion module includes: an off-axis main expansion base plate, and an off-axis main expansion objective lens, an off-axis main expansion folding mirror, an off-axis main expansion reflecting mirror, and an off-axis main expansion secondary mirror mounted on the off-axis main expansion base plate; The off-axis main expansion base plate is made of Invar steel.

3. The system according to claim 2, characterized in that, The system base plate is made of aluminum alloy. The system base plate is connected to the off-axis main expansion base plate via an elastic connector. The elastic connector absorbs the thermal deformation displacement between the system base plate and the off-axis main expansion base plate through elastic deformation, thereby isolating the thermal deformation from being transmitted to the off-axis main expansion module.

4. The system according to claim 1, characterized in that, Both the measuring mirror module and the imaging mirror module have a centering structure inside their respective barrels. The centering structure includes a centering frame and a lens; The lens is fixed to the centering frame by a pressure ring and glue injection. A replaceable trimming ring is provided between the centering frame and the lens barrel for adjusting the axial spacing of the lens.

5. The system according to claim 3, characterized in that, The imaging lens module is equipped with a temperature compensation detector at the image plane position. The temperature compensation detector has an electronically controlled moving focus function to compensate for image plane drift caused by temperature changes. The temperature-compensated detector and the elastic connector together constitute an active-passive coordinated thermal compensation system, wherein the elastic connector is used to suppress thermally induced structural deformation, and the temperature-compensated detector is used to correct residual image plane drift.

6. The system according to claim 1, characterized in that, Both the measuring mirror module and the imaging mirror module are equipped with attenuation mirrors in their optical paths. The attenuation mirror assembly includes multiple attenuation plates arranged at a preset angle to the optical axis, and the multiple attenuation plates are arranged in a non-coplanar Z-shaped layout in the optical path to suppress stray light.

7. The system according to claim 1, characterized in that, The system base plate is equipped with multiple adjustable feet; The adjustable foot includes a foot base, a first screw, a second screw, and a third screw; The second screw has a reverse thread. Rotating the second screw can cause the first screw and the third screw to move synchronously toward or away from each other to adjust the system height.

8. A method for assembling and adjusting a modular off-axis optical detection system, characterized in that, The method for assembling and adjusting the modular off-axis optical detection system according to any one of claims 1-7 includes: The optical axis of the off-axis main expansion module is used as the assembly and adjustment reference axis for the entire system. After internal optical path adjustments are made to the off-axis main expansion module, the measuring mirror group module, and the imaging mirror group module respectively, the off-axis main expansion module, the beam splitter group, the measuring mirror group module, and the imaging mirror group module are installed on the system base plate. Based on the assembly reference axis, adjust the positions and orientations of the beam splitter group, the measurement lens group module, and the imaging lens group module to complete the optical path docking and system calibration.

9. The method according to claim 8, characterized in that, Internal optical path adjustment of the off-axis main expansion module includes: The interferometer is placed at the focal point of the off-axis main expansion objective, and a plane mirror is placed at the light outlet of the off-axis main expansion module. The attitude of the plane mirror is adjusted to collimate the light beam emitted from the off-axis main expansion module and establish an initial coarse adjustment reference. Keeping the interferometer in its current position, the first theodolite is used to aim at the collimated beam emitted from the interferometer, and the optical axis of the collimated beam is extracted as the reference optical axis for subsequent assembly and adjustment. A second theodolite is set at a predetermined position in the direction of the outgoing light of the off-axis primary expander mirror. The two theodolites are aimed at each other to establish the outgoing light angle reference required for the installation of the off-axis primary expander mirror and the off-axis primary expander mirror. The off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror are installed in sequence. The attitude of the off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror is adjusted so that the collimated beam emitted by the first theodolite is reflected by the off-axis main expanding and folding mirror and the off-axis main expanding and reflecting mirror in sequence and then enters the second theodolite, and the autocollimated image coincides with the crosshairs of the theodolite eyepiece. Remove the first and second theodolites, install an off-axis primary and secondary mirror, place an interferometer at a predetermined position on the light-emitting side of the off-axis primary and secondary mirror, so that the reflected beam of the plane mirror interferes with the emitted beam of the interferometer; using the system wave aberration as the evaluation function, adjust the attitude of the off-axis primary and secondary mirror until the root mean square value and peak-valley value of the wave aberration simultaneously reach the preset optical design index.

10. The method according to claim 8, characterized in that, The internal optical path of the measuring mirror module and the imaging mirror module is adjusted, including: A through-hole fixture is installed on the barrels of the measuring lens module and the imaging lens module respectively. The reference optical axes of the measuring lens module and the imaging lens module are led out through a theodolite. The through-hole fixture is used to establish a transferable correspondence between the mechanical axis of the lens barrel and the optical reference. Adjust the positions of the barrels of the measuring mirror module and the imaging mirror module respectively, so that the crosshairs of the through-hole fixture coincide with the crosshairs of the corresponding theodolite eyepiece; Remove the through-hole fixture and install the measuring lens module and the optical lens groups inside the imaging lens module in sequence.

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