Intermediate infrared laser fiber coupling method and system based on visible light reverse guidance
By employing a visible light reverse guidance method and a strategy of calibration followed by regression, the problem of initial alignment difficulties in mid-infrared laser fiber coupling was solved, enabling rapid, accurate, and visualized alignment and coupling of mid-infrared lasers, thereby improving coupling efficiency and system stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-04-07
AI Technical Summary
In existing mid-infrared laser fiber-space coupling technology, the invisibility of mid-infrared lasers makes initial alignment difficult, the multi-axis adjustment range is limited, and it is difficult to accurately control the laser beam waist position, which affects coupling efficiency and system stability.
A mid-infrared laser fiber coupling method based on visible light reverse guidance is adopted. By setting up a mid-infrared laser, a beam guiding module, a beam collimation evaluation module and a reflective collimator, the target fiber is disconnected and connected using a visible laser source. The initial reference optical path and the spatial reference optical path are first calibrated, and then the position and attitude of the reflector and aperture are adjusted to make the mid-infrared laser and the visible beam completely coincide, so as to achieve visual alignment and coupling.
It enables rapid, precise, and visual alignment and coupling of mid-infrared lasers, improving operational intuitiveness and accuracy, and providing a fast and reliable laser transmission solution.
Smart Images
Figure CN121806307A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of mid-infrared laser fiber-space coupling technology, specifically to a mid-infrared laser fiber coupling method and system based on visible light reverse guidance. Background Technology
[0002] Precise online diagnostics of thermochemical reaction flows (such as combustion processes) are crucial for understanding reaction mechanisms, optimizing system design, and controlling pollutant formation. Mid-infrared laser absorption spectroscopy, with its high sensitivity, high resolution, and ability to directly measure various key molecules (such as H₂O, CO, CO₂, NOx, and CH₄), has become a powerful diagnostic tool in this field. The development of mid-infrared laser sources, such as quantum cascade lasers, has further promoted its application in harsh and complex environments.
[0003] However, in actual experimental setups such as burners, engines, or reactors, there are often spatial constraints and complex geometric layouts between the laser and the measurement point. Using optical fibers to flexibly transmit mid-infrared laser light to the measurement point is the best solution.
[0004] Currently, there are relatively limited fiber-space coupling technology solutions for mid-infrared lasers. For coupling of mid-infrared lasers, existing technologies mainly adopt two approaches: one is to use the lens-type fiber collimator scheme and use mid-infrared light-transmitting materials to make the lens; the other is to use reflective optical elements such as off-axis parabolic mirrors to avoid the dispersion and absorption loss of transmission elements.
[0005] However, both approaches have significant drawbacks: the lens-type approach is limited by the cost and processing difficulty of mid-infrared materials, and also suffers from chromatic aberration and thermal lensing effects; the reflective approach, while free from dispersion problems, is extremely sensitive to assembly and adjustment errors and is complex to debug. In addition, the invisibility of infrared lasers makes initial alignment difficult, and the limited displacement range of the multi-axis adjustment frame makes it difficult to accurately control the laser beam waist position, which severely restricts coupling efficiency and system stability. Summary of the Invention
[0006] The purpose of this invention is to provide a method and system for fiber coupling of mid-infrared laser based on visible light reverse guidance, so as to solve the technical problems of difficulty in initial alignment, limited displacement range of multi-axis adjustment frame, and difficulty in accurately controlling the laser beam waist position caused by the invisibility of mid-infrared laser in the prior art.
[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A mid-infrared laser fiber coupling system based on visible light reverse guidance, comprising: A mid-infrared laser, a beam guiding module, a beam collimation evaluation module, and a reflective collimator are arranged sequentially along the main optical path. The reflective collimator is connected to a visible laser source via a target optical fiber, and the visible laser source is detachably connected to the far end of the target optical fiber. The mid-infrared laser and the beam guiding module form an initial reference optical path, and the visible laser source, the reflective collimator, the beam collimation evaluation module, and the beam guiding module form a spatial reference optical path; Optical path coupling is performed between the initial reference optical path and the spatial reference optical path until the beam of the mid-infrared laser completely overlaps with the initial reference optical path and the spatial reference optical path.
[0008] As a preferred embodiment of the present invention, the beam guiding module includes a first reflector and a second reflector, both of which are mounted on a three-dimensional adjustment frame; In the initial reference optical path formed, the first reflector is used to receive the beam from the mid-infrared laser, and the propagation direction of the beam from the mid-infrared laser in a two-dimensional plane is controlled by adjusting the orientation of the first reflector.
[0009] As a preferred embodiment of the present invention, the beam guiding module includes a first aperture and a second aperture. In the formed spatial reference optical path, by adjusting the position and orientation of the second reflector, the first aperture, and the second aperture, the visible beam of the visible laser source passes precisely and backward through the center of the apertures of the second aperture and the first aperture in sequence, and the visible beam is precisely coaxial with the mechanical axis defined by the center of the apertures of the second aperture and the first aperture, until the visible beam is at the center of the effective reflection area of the second reflector.
[0010] As a preferred embodiment of the present invention, the reflective collimator is further connected to an output collimator via a target optical fiber. The output collimator is detachably connected to the far-end output port of the target optical fiber, and the mid-wave infrared camera is aligned with the light output direction of the output collimator. The mid-infrared laser is activated, and its output spot is directly observed, captured, and analyzed using a mid-wave infrared camera.
[0011] As a preferred embodiment of the present invention, the aperture of the first aperture and the second aperture is 1mm-5mm, and the distance between the first aperture and the second aperture is 10cm-50cm.
[0012] As a preferred embodiment of the present invention, the reflective collimator includes a fiber-coupled 90° off-axis parabolic mirror. The output collimator is a lens-type or reflective collimator.
[0013] In addition, the present invention also provides a mid-infrared laser fiber coupling method based on visible light reverse guidance, comprising the following steps: Calibrate the initial reference optical path: Turn on the mid-infrared laser, place the infrared colorimetric card in front of the first reflector, and adjust the pitch and deflection angles of the first reflector to ensure that the mid-infrared laser spot is stably located in the center of the effective reflection area of the first reflector itself. Calibrate the reverse-guided spatial reference optical path: turn off the mid-infrared laser and turn on the visible laser source. Adjust the position and orientation of the first aperture, the second aperture, and the second reflector so that the visible light, after being collimated by the reflective collimator, passes precisely through the center of the holes of the first aperture and the second aperture in sequence, and the spot of the visible light is located at the center of the effective reflection area of the second reflector. Couple the dual-phase optical path: Turn off the visible laser source again and turn on the mid-infrared laser. Adjust the attitude of the first and second reflectors so that the mid-infrared laser completely coincides with the calibrated initial reference optical path and the reverse-guided spatial reference optical path. Verification of optical path coupling effect: The output spot of the mid-infrared laser is directly observed, captured and analyzed by a mid-wave infrared camera. The coupling effect is qualitatively and intuitively verified by analyzing the image of the spot.
[0014] As a preferred embodiment of the present invention, when coupling the dual-phase optical path, the attitude of the first reflector is first adjusted so that the mid-infrared laser can reach the center of the effective reflection area of the second reflector, and then the attitude of the second reflector is adjusted so that the mid-infrared laser passes through the center of the holes of the first aperture and the second aperture in sequence. By repeatedly adjusting the attitudes of the first and second reflectors, the mid-infrared laser is made to completely overlap with the calibrated initial reference optical path and the reverse-guided spatial reference optical path.
[0015] As a preferred embodiment of the present invention, when calibrating the reverse guidance space reference optical path, a visible laser source is turned on, the visible laser is transmitted through the target optical fiber, and the visible laser is injected from the first port of the reflective collimator and collimated, and then a parallel visible beam is output from the second port of the reflective collimator. Adjust the position and orientation of the second reflector to ensure that the visible laser spot is stably located at the center of the effective reflection area of the second reflector; The positions and orientations of the first and second apertures are then adjusted to ensure that the visible laser beam passes precisely through the centers of the holes of the second and first apertures in sequence, so as to establish a spatial reference optical path from the reflective collimator to the second mirror.
[0016] As a preferred embodiment of the present invention When the output spot of the mid-infrared laser captured by the mid-wave infrared camera is a circular, uniformly distributed, and stable near-Gaussian spot, it indicates high beam quality and good coupling.
[0017] Compared with the prior art, the present invention has the following advantages: This invention first establishes an initial reference optical path from the laser to the first reflecting mirror, and then establishes a spatial reference optical path from the reflective collimator to the second reflecting mirror (by first calibrating the reference optical path). Next, mid-infrared laser coupling is performed (followed by optical path coupling regression), forming a coupling mechanism of "first establishing an absolute reference" and "then completing relative calibration," achieving rapid, accurate, and visual alignment and coupling of the mid-infrared laser. This method is intuitive to operate and highly accurate, providing a fast and reliable laser transmission solution for the diagnosis of thermochemical reaction flows. Attached Figure Description
[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of a mid-infrared laser fiber coupling system connected to a visible laser source according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the coupling effect verification system when connecting a mid-wave infrared camera according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of the infrared laser fiber coupling method in an embodiment of the present invention; The labels in the diagram represent the following: 1. Mid-infrared laser, 2. First reflector, 3. Second reflector, 4. First aperture, 5. Second aperture and 6. Reflective collimator, 7. Target optical fiber, 8. Visible laser source, 9. Output collimator, 10. Mid-wave infrared camera. Detailed Implementation
[0020] 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.
[0021] like Figure 1As shown, the present invention provides a mid-infrared laser fiber coupling system based on visible light reverse guidance, including a mid-infrared laser 1, a beam guiding module, a beam collimation evaluation module and a reflective collimator 6 arranged sequentially along the main optical path.
[0022] Among them, the reflective collimator 6 is connected to the visible laser source 8 through the target optical fiber 7, and the visible laser source 8 is detachably connected to the far end of the target optical fiber 7.
[0023] The mid-infrared laser 1 and the beam guiding module form the initial reference optical path, while the visible laser source 8, the reflective collimator 6, the beam collimation evaluation module and the beam guiding module form the spatial reference optical path.
[0024] Optical path coupling is performed between the initial reference optical path and the spatial reference optical path until the beam of the mid-infrared laser 1 completely overlaps with the initial reference optical path and the spatial reference optical path.
[0025] This implementation first establishes an initial reference optical path from the laser to the first reflector, and then establishes a spatial reference optical path from the reflective collimator to the second reflector (first completing the reference optical path calibration). Then, mid-infrared laser coupling is performed (after completing the optical path coupling regression). Therefore, the core of this implementation lies in the visible light reverse guidance formed by the reflective collimator to the second reflector, and the system of "visual reference optical path anchoring" formed by first calibrating the reference optical path (initial reference optical path and spatial reference optical path) and then coupling the two initial reference optical paths and the spatial reference optical path back to form a "visual reference optical path anchoring". This forms a coupling mechanism of "first establishing an absolute reference" and "then completing relative correction".
[0026] The beam guiding module includes a first reflector 2 and a second reflector 3. Both the first reflector 2 and the second reflector 3 are mounted on a three-dimensional adjustment frame. In the initial reference optical path, the first reflector 2 is used to receive the beam from the mid-infrared laser 1. By adjusting the attitude of the first reflector 2, the propagation direction of the beam from the mid-infrared laser 1 in the two-dimensional plane can be controlled.
[0027] By finely adjusting the pitch and deflection angles of the first reflecting mirror 2, the beam of the mid-infrared laser 1 is ensured to be stably located at the center of the effective reflection area of the first reflecting mirror 2. The core purpose of this step is to establish an initial and reliable spatial reference point using the center of the mirror surface of the first reflecting mirror 2, thereby initially establishing the optical path direction from the mid-infrared laser 1 to the first reflecting mirror 2.
[0028] The beam guiding module includes a first aperture 4 and a second aperture 5. In the formed spatial reference optical path, by adjusting the position and orientation of the second reflector 3, the first aperture 4 and the second aperture 5, the visible beam of the visible laser source 8 is made to pass through the center of the aperture of the second aperture 5 and the first aperture 4 in a precise reverse direction in sequence. The visible beam is precisely coaxial with the mechanical axis defined by the center of the aperture of the second aperture 5 and the first aperture 4 until the visible beam is at the center of the effective reflection area of the second reflector 3. The aperture of the first aperture 4 and the second aperture 5 is 1mm-5mm, and the distance between the first aperture 4 and the second aperture 5 is 10cm-50cm.
[0029] Turn on the visible laser source 8, so that the visible laser is transmitted through the target optical fiber 7, injected from the first port of the reflective collimator 6 and collimated, and then output as a parallel visible beam from its second port. First, adjust the position and orientation of the second reflector 3 to ensure that the visible light spot is stably located in the center of the effective reflection area of the second reflector 3; Then adjust the position and orientation of the first aperture 4 and the second aperture 5 to ensure that the visible light beam passes precisely through the center of the holes of the second aperture 5 and the first aperture 4 in sequence; When the center of the beam and the center of the aperture are exactly coincident, it indicates that the optical axis of the reflective collimator 6 has been precisely calibrated, and the spatial reference optical path from the reflective collimator 6 to the second reflector 3 has been successfully established. When directly adjusting the mid-infrared optical path, the operator is essentially groping in the dark because the laser is invisible. Each mirror and aperture has multiple degrees of freedom, and adjusting any component will unknowingly affect the subsequent optical path. This results in a multivariable, strongly coupled, and non-real-time feedback "blind adjustment" system, which is extremely inefficient and difficult to converge to the optimal state.
[0030] When this embodiment uses visible light to guide the formation of a spatial reference optical path, it can accurately determine whether the beam passes through the center of the aperture. The operator can directly observe with the naked eye whether the visible light spot accurately passes through the center of the two apertures, realizing real-time and continuous visual feedback adjustment. The operation is intuitive. At the same time, the visible light used for calibration and the mid-infrared laser used for final operation use the same set of optical elements (the same reflecting mirror and the same aperture). This eliminates the error caused by the inconsistency of the reference due to the change of observation tools or different detection wavelengths, and ensures that the calibration reference and the working optical path are highly consistent in geometry.
[0031] The reflective collimator 6 is also connected to the output collimator 9 via the target optical fiber 7. The output collimator 9 is detachably connected to the far end of the target optical fiber 7, and the mid-wave infrared camera 10 is aligned with the light output direction of the output collimator 9.
[0032] The mid-infrared laser is activated, and the output spot of the mid-infrared laser is directly observed, captured, and analyzed using a mid-wave infrared camera 10.
[0033] After activating the mid-infrared laser 1, the output spot of the mid-infrared laser was directly observed, captured, and analyzed using a mid-wave infrared camera 10. A circular, uniformly distributed, and stable near-Gaussian spot indicates high beam quality and good coupling. By analyzing the image of the spot, the coupling effect can be qualitatively and intuitively verified, confirming that the beam has been successfully coupled into the optical fiber in a high-quality mode and output successfully.
[0034] In this embodiment, the reflective collimator 6 contains a fiber-coupled 90° off-axis parabolic mirror; the output collimator 9 is a lens-type or reflective collimator.
[0035] In one embodiment of this method, the mid-infrared laser 1 is a quantum cascade laser with an output wavelength of 4.6 μm; the first reflector 2 and the second reflector 3 are both gold-plated high-reflectivity mirrors, mounted on a three-dimensional precision adjustment frame; the first aperture 4 and the second aperture 5 have apertures of 2 mm and a distance of 30 cm between them; the reflective collimator 6 includes a 90° off-axis parabolic mirror with a focal length of 33 mm and a light-transmitting aperture of 16.5 mm; the target fiber 7 is a fluoride glass fiber with a length of 2 m, a core diameter of 100 μm, and a numerical aperture of 0.20; the visible laser source 8 is a semiconductor laser pointer with a wavelength of 650 nm; the output collimator 9 is a lens collimator; and the response band of the mid-wave infrared camera 10 is 3-5 μm.
[0036] This embodiment addresses the challenges and time-consuming processes associated with docking mid-infrared lasers with reflective collimators due to their invisibility. It innovatively employs a visible light guidance principle, utilizing a progressive "calibrate first, then return" strategy to achieve rapid, accurate, and visualized alignment and coupling of mid-infrared lasers. This method is intuitive and highly precise, providing a fast and reliable laser transmission solution for thermochemical reaction flow diagnosis.
[0037] Furthermore, based on the aforementioned mid-infrared laser coupling system guided by visible light reverse guidance, this invention also discloses a mid-infrared laser fiber coupling method guided by visible light reverse guidance, comprising the following steps: Calibrate the initial reference optical path: Turn on the mid-infrared laser, place the infrared colorimetric card in front of the first reflector, and adjust the pitch and deflection angles of the first reflector to ensure that the mid-infrared laser spot is stably located in the center of the effective reflection area of the first reflector itself.
[0038] The effective reflection area of the first reflector is a high reflectivity area, and the reflection loss at the center is the lowest. This ensures that the mid-infrared laser can hit the effective area of the first reflector from the beginning, avoids the laser from deviating from the system's optical path, and establishes a reliable incident reference point.
[0039] Calibrate the reverse-guided spatial reference optical path: Turn off the mid-infrared laser and turn on the visible laser source. Adjust the position and orientation of the first aperture, the second aperture, and the second reflector so that the visible light, after being collimated by the reflective collimator, passes precisely through the center of the holes of the first and second apertures in sequence, and the spot of the visible light is located at the center of the effective reflection area of the second reflector.
[0040] The effective reflection area of the second mirror is a high reflectivity region, and the reflection loss is lowest at the center. The second mirror is used as the end point of the visible light reference optical path to ensure that the light emitted from the reflective collimator accurately hits the center of the mirror, thereby establishing the spatial orientation of the entire optical path.
[0041] When calibrating the reverse-guided space reference optical path, the visible laser source is turned on. The visible laser is transmitted through the target optical fiber. The visible laser is injected from the first port of the reflective collimator and collimated, and then output as a parallel visible beam from the second port of the reflective collimator. Adjust the position and orientation of the second reflector to ensure that the visible laser spot is stably located at the center of the effective reflection area of the second reflector; The positions and orientations of the first and second apertures are then adjusted to ensure that the visible laser beam passes precisely through the centers of the holes in the second and first apertures in sequence, thus establishing a spatial reference optical path from the reflective collimator to the second mirror.
[0042] Couple the dual-phase optical path: Turn off the visible laser source again and turn on the mid-infrared laser. Adjust the attitude of the first and second reflectors so that the mid-infrared laser completely coincides with the calibrated initial reference optical path and the reverse-guided spatial reference optical path.
[0043] During the coupling phase, fine-tuning of the first reflector is permitted to allow the mid-infrared laser to "return" to the reference optical path. After adjustment, the beam spot may deviate slightly from the physical center of the first reflector, but this does not affect the system performance at all. This is because the core function of the first reflector in this scheme is to change the beam direction. As long as its reflecting surface remains clean and within the effective area, and the adjustment allows the beam to accurately reach the next target (the calibration area of the second reflector), its task is accomplished.
[0044] When coupling the dual-phase optical path, first adjust the orientation of the first reflector so that the mid-infrared laser can reach the center of the effective reflection area of the second reflector. Then adjust the orientation of the second reflector so that the mid-infrared laser passes through the center of the holes of the first and second apertures in sequence. By repeatedly adjusting the attitudes of the first and second reflectors, the mid-infrared laser is made to completely overlap with the calibrated initial reference optical path and the reverse-guided spatial reference optical path.
[0045] Fine-tuning the orientation of the second reflector compensates for the subtle differences in wavelength and beam quality between visible and mid-infrared light, ensuring that the mid-infrared laser beam not only "hits" the reflector but also originates from that point and is precisely emitted along the reference optical axis (i.e., passing through the centers of the two aperture stops) to the reflective collimator. This fine-tuning is an angular adjustment around the calibrated "reflection point" and does not change the spatial position of that "reflection point" (because the physical position of the reflector itself remains unchanged). Therefore, it is a precise correction of the beam's exit direction without disrupting the established geometric position of the reference point, perfectly aligning it with the axis defined by the aperture stops. Thus, this adjustment does not negate the significance of calibration but rather represents the final, precise closed loop based on calibration, ensuring the highest degree of coaxial alignment between the invisible working laser and the reference established by the visible light.
[0046] Verification of optical path coupling effect: The output spot of the mid-infrared laser is directly observed, captured and analyzed by a mid-wave infrared camera. The coupling effect is qualitatively and intuitively verified by analyzing the image of the spot.
[0047] When the output spot of the mid-infrared laser captured by the mid-wave infrared camera is a circular, uniformly distributed, and stable near-Gaussian spot, it indicates that the beam quality is high and the coupling state is good.
[0048] The advantages of this implementation method using the "calibrate first, then regress" strategy are: visual operation, reducing reliance on specialized equipment; reducing adjustment variables, improving alignment efficiency and success rate; suitable for complex experimental environments, supporting rapid deployment and repeated setup, strong repeatability, and once the reference optical path is established, subsequent repeated coupling or optical path reconstruction is very rapid.
[0049] Therefore, this embodiment addresses the problem of difficult and time-consuming docking with reflective collimators caused by the invisibility of mid-infrared lasers. It innovatively employs a visible light guidance principle, using a progressive strategy of "calibration first, then regression" to achieve rapid, accurate, and visual alignment and coupling of mid-infrared lasers. This method is intuitive and highly accurate, providing a fast and reliable laser transmission solution for the diagnosis of thermochemical reaction flows.
[0050] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.
Claims
1. A mid-infrared laser fiber coupling system based on visible light reverse guidance, characterized in that, include: A mid-infrared laser (1), a beam guiding module, a beam collimation evaluation module, and a reflective collimator (6) are arranged sequentially along the main optical path. The reflective collimator (6) is connected to a visible laser source (8) via a target optical fiber (7), and the visible laser source (8) is detachably connected to the far end of the target optical fiber (7). The mid-infrared laser (1) and the beam guiding module form an initial reference optical path, and the visible laser source (8), the reflective collimator (6), the beam collimation evaluation module and the beam guiding module form a spatial reference optical path; The initial reference optical path and the spatial reference optical path are optically coupled until the beam of the mid-infrared laser (1) completely overlaps with the initial reference optical path and the spatial reference optical path.
2. The mid-infrared laser fiber coupling system based on visible light reverse guidance according to claim 1, characterized in that, The beam guiding module includes a first reflector (2) and a second reflector (3), both of which are mounted on a three-dimensional adjustment frame; In the initial reference optical path formed, the first reflector (2) is used to receive the beam from the mid-infrared laser (1), and the propagation direction of the beam from the mid-infrared laser (1) in the two-dimensional plane is controlled by adjusting the orientation of the first reflector (2).
3. The mid-infrared laser fiber coupling system based on visible light reverse guidance according to claim 2, characterized in that, The beam guiding module includes a first aperture (4) and a second aperture (5). In the formed spatial reference optical path, by adjusting the position and orientation of the second reflector (3), the first aperture (4) and the second aperture (5), the visible beam of the visible laser source (8) passes precisely in the opposite direction through the center of the holes of the second aperture (5) and the first aperture (4), and the visible beam is precisely coaxial with the mechanical axis defined by the center of the holes of the second aperture (5) and the first aperture (4), until the visible beam is at the center of the effective reflection area of the second reflector (3).
4. The mid-infrared laser fiber coupling system based on visible light reverse guidance according to claim 1, characterized in that, The reflective collimator (6) is also connected to an output collimator (9) via a target optical fiber (7). The output collimator (9) is detachably connected to the far end of the target optical fiber (7). The mid-wave infrared camera (10) is aligned with the light output direction of the output collimator (9). The mid-infrared laser is turned on, and the output spot of the mid-infrared laser is directly observed, captured and analyzed by a mid-wave infrared camera (10).
5. A mid-infrared laser fiber coupling system based on visible light reverse guidance according to claim 2, characterized in that, The aperture of the first aperture (4) and the second aperture (5) is 1mm-5mm, and the distance between the first aperture (4) and the second aperture (5) is 10cm-50cm.
6. A mid-infrared laser fiber coupling system based on visible light reverse guidance according to claim 4, characterized in that, The reflective collimator (6) contains a fiber-coupled 90° off-axis parabolic mirror; The output collimator (9) is a lens-type or reflective collimator.
7. A method for fiber coupling of mid-infrared laser based on visible light reverse guidance, characterized in that, A mid-infrared laser fiber coupling system based on visible light reverse guidance as described in any one of claims 1-6 includes the following steps: Calibrate the initial reference optical path: Turn on the mid-infrared laser, place the infrared colorimetric card in front of the first reflector, and adjust the pitch and deflection angles of the first reflector to ensure that the mid-infrared laser spot is stably located in the center of the effective reflection area of the first reflector itself. Calibrate the reverse-guided spatial reference optical path: turn off the mid-infrared laser and turn on the visible laser source. Adjust the position and orientation of the first aperture, the second aperture, and the second reflector so that the visible light, after being collimated by the reflective collimator, passes precisely through the center of the holes of the first aperture and the second aperture in sequence, and the spot of the visible light is located at the center of the effective reflection area of the second reflector. Couple the dual-phase optical path: Turn off the visible laser source again and turn on the mid-infrared laser. Adjust the attitude of the first and second reflectors so that the mid-infrared laser completely coincides with the calibrated initial reference optical path and the reverse-guided spatial reference optical path. Verification of optical path coupling effect: The output spot of the mid-infrared laser is directly observed, captured and analyzed by a mid-wave infrared camera. The coupling effect is qualitatively and intuitively verified by analyzing the image of the spot.
8. The method for fiber coupling of mid-infrared laser based on visible light reverse guidance according to claim 7, characterized in that, When coupling the dual-phase optical path, first adjust the orientation of the first reflector so that the mid-infrared laser can reach the center of the effective reflection area of the second reflector, and then adjust the orientation of the second reflector so that the mid-infrared laser passes through the center of the holes of the first and second apertures in sequence. By repeatedly adjusting the attitudes of the first and second reflectors, the mid-infrared laser is made to completely overlap with the calibrated initial reference optical path and the reverse-guided spatial reference optical path.
9. A method for fiber coupling of mid-infrared laser based on visible light reverse guidance according to claim 7, characterized in that, When calibrating the reverse-guided space reference optical path, a visible laser source is turned on. The visible laser is transmitted through the target optical fiber. The visible laser is injected from the first port of the reflective collimator and collimated, and then a parallel visible beam is output from the second port of the reflective collimator. Adjust the position and orientation of the second reflector to ensure that the visible laser spot is stably located at the center of the effective reflection area of the second reflector; The positions and orientations of the first and second apertures are then adjusted to ensure that the visible laser beam passes precisely through the centers of the holes of the second and first apertures in sequence, so as to establish a spatial reference optical path from the reflective collimator to the second mirror.
10. A method for fiber coupling of mid-infrared laser based on visible light reverse guidance according to claim 7, characterized in that, When the output spot of the mid-infrared laser captured by the mid-wave infrared camera is a circular, uniformly distributed, and stable near-Gaussian spot, it indicates that the beam quality is high and the coupling state is good.