A transmission-type high-power laser emission system

Abstract

This application discloses a transmission-type high-power laser emitting system, relating to the technical field of high-power laser systems. The system's laser incident end is connected to a high-power fiber laser for receiving the laser beam, and its laser emitting end is used to focus the laser beam to a target location. The system includes a laser emitting mirror group, an emitting mirror tube, a focusing motor, and a control circuit board. The laser emitting mirror group is disposed inside the emitting mirror tube and includes a laser emitting eyepiece group and a laser emitting objective lens group. The laser emitting eyepiece group is located at the incident end, and the laser emitting objective lens group is located at the laser emitting end. The focusing motor is used to move the laser emitting eyepiece group through a mechanical connector to achieve system focusing. The control circuit board is used to control the focusing motor to rotate and focus according to a focusing signal. The technical solution of this application has a simple system structure, relatively high temperature stability, and can achieve directional focusing of a high-power laser beam over a long distance.

Description

Technical Field

[0001] This application relates to the technical field of high-power laser systems, and more specifically, to a transmission-type high-power laser emitting system. Background Technology

[0002] High-energy laser systems, with their advantages of long transmission distance, high accuracy, fast turning speed, and high cost-effectiveness, combined with their ease of deployment on various platforms including sea, land, and air, have become the most promising new concept weapon for which both domestic and international companies are vying to develop them. The basic working principle of a high-energy laser system is to directly destroy the target using a high-power laser. The beam control emission system has become its core component. Typically, the emission system is required to both directionally emit the high-power laser and focus it onto the target in the far field to achieve destruction, and to track the target within a certain distance. However, fixed-focus optical systems cannot achieve continuous focusing, especially when tracking moving targets, where the beam density cannot reach the damage threshold, resulting in excessively long destruction times. Therefore, continuously focusing high-power laser emission optical systems, when applied to high-energy laser systems, not only achieve a higher average power density at the far-field target focus point but also maintain the stability of the focused beam power density during rapid target movement.

[0003] In recent years, various research institutions have conducted research on high-power laser emission systems. Existing research mainly analyzes and compares different optical systems applied to high-power laser technology. When the effective distance is long and energy concentration is required, a focusing emission system is generally used. Focusing emission systems can be divided into two structural types: transmission emission systems and reflection emission systems. Existing literature mainly focuses on reflection emission focusing systems. For example, Suzhou University used a primary and secondary off-axis dual-reflector structure to simulate the focusing effect on a target at 1km; Beijing Institute of Technology used a catadioptric two-stage beam expander optical system to achieve focusing within a range of 0.5~5km; the China Air-to-Air Missile Research Institute conducted a detailed analysis of the parameter design and focusing characteristics of the Cassegrain coaxial zoom emission system; Hefei University of Technology combined the Cassegrain system with a lens group, changing the distance between the Cassegrain system and the lens group to adjust the focus, so that the laser is focused on the moving target. Existing reflective systems have a large output aperture and no chromatic aberration, but they are very sensitive to thermal deformation of structural components during laser transmission and have low temperature stability. They cannot avoid the problem of excessive temperature rise during operation. When the system temperature rises too high, it is difficult to control the focusing accuracy, thus failing to meet the requirements for target destruction (such as UAVs) within a certain range. Summary of the Invention

[0004] The purpose of this application is to provide a transmission-type high-power laser emission system that solves the problems of low temperature stability and poor system reliability in the prior art.

[0005] The technical solution of this application is: a transmission-type high-power laser emission system is provided. The transmission-type high-power laser emission system includes a laser input end and a laser output end. The laser input end is connected to the output connector of a high-power fiber laser and is used to receive the laser beam emitted by the fiber laser. The laser output end is used to focus the laser beam to the target position.

[0006] The transmissive high-power laser emitting system includes a laser emitting mirror group, an emitting mirror tube, a focusing motor, and a control circuit board.

[0007] The laser emitting lens group is disposed inside the emitting lens tube. The laser emitting lens group includes a laser emitting eyepiece group and a laser emitting objective lens group. The laser emitting eyepiece group is located at the laser incident end, and the laser emitting objective lens group is located at the laser emitting end. The diameter of the laser emitting eyepiece group is smaller than the diameter of the laser emitting objective lens group.

[0008] The laser emitting eyepiece group includes two concave lenses with their concave surfaces facing each other. The laser emitting eyepiece group is used to expand the incident laser beam to increase the divergence angle of the laser beam, so that the laser beam can be uniformly propagated to the laser emitting objective lens group.

[0009] The laser emitting objective lens group includes three convex lenses, with the convex surfaces of the three convex lenses facing the direction of laser emission. The laser emitting objective lens group is used to uniformly focus the expanded laser beam to the target position.

[0010] The focusing motor is located on the outside of the emitting lens barrel near the laser emitting eyepiece group, and is used to adjust the position of the laser emitting eyepiece group to achieve system focal length adjustment;

[0011] The control circuit board is used to receive the focusing input signal and control the focusing motor to perform focusing according to the focusing input signal.

[0012] Furthermore, the laser emitting eyepiece assembly includes, in sequence along the optical path, a first laser emitting eyepiece and a second laser emitting eyepiece;

[0013] The first laser emitting eyepiece has a convex side with a radius of curvature of 500.3 mm and a concave side with a radius of curvature of 77.9 mm.

[0014] The object side of the second laser emitting eyepiece is concave with a radius of curvature of -88.4 mm, while the mirror side of the second laser emitting eyepiece is flat.

[0015] Furthermore, the focal length of the first laser emitting eyepiece is -202mm, and the focal length of the second laser emitting eyepiece is -193mm;

[0016] The distance between the first laser emitting eyepiece and the second laser emitting eyepiece is 10mm.

[0017] Furthermore, the laser emitting objective lens group includes, in sequence along the optical path, a first laser emitting objective lens, a second laser emitting objective lens, and a third laser emitting objective lens;

[0018] The object side of the first laser emitting objective lens is concave with a radius of curvature of -500.3 mm, and the mirror side of the first laser emitting objective lens is convex with a radius of curvature of -380.9 mm.

[0019] The second laser emitting objective lens has a concave side surface with a radius of curvature of -859 mm, while the first laser emitting objective lens has a convex side surface with a radius of curvature of -423.8 mm.

[0020] The object side of the third laser emitting objective lens is flat, and the mirror side of the third laser emitting objective lens is convex with a radius of curvature of -621mm.

[0021] Furthermore, the focal length of the first laser emitting objective is 3292mm, the focal length of the second laser emitting objective is 1796mm, and the focal length of the third laser emitting objective is 1355mm.

[0022] The distance between the first laser emitting objective and the second laser emitting objective is 8.75 mm; the distance between the second laser emitting objective and the third laser emitting objective is 2 mm.

[0023] Furthermore, the distance between the laser emitting eyepiece group and the laser emitting objective lens group ranges from 470mm to 471.5mm, corresponding to a focusing position of the transmission-type high-power laser emitting system ranging from 2km to 0.3km. The greater the distance between the laser emitting eyepiece group and the laser emitting objective lens group, the closer the focusing position of the system; the smaller the distance between the laser emitting eyepiece group and the laser emitting objective lens group, the farther the focusing position of the system.

[0024] Furthermore, the focusing motor is connected to the laser emitting eyepiece group via a mechanical connector, and is used to move the laser emitting eyepiece group through the mechanical connector to change the relative position between the laser emitting eyepiece group and the laser emitting objective lens group, thereby realizing the system focal length adjustment; the control circuit board is disposed on the emitting lens barrel, and the control circuit board is electrically connected to the focusing motor.

[0025] Furthermore, an aperture stop is provided at the laser incident end, and the aperture stop is located on the side of the laser emitting eyepiece group closer to the fiber laser.

[0026] Furthermore, each lens in the laser emitting eyepiece group and the laser emitting objective group is made of the same high-purity fused silica material, the refractive index of which is between 1.45 and 1.46.

[0027] The technical solution of this application also provides an application of a transmission-type high-power laser emission system in achieving target destruction, which includes the following steps:

[0028] S1: Determine the target location that needs to be damaged, and align the laser output end of the system with the target location;

[0029] S2: Based on the distance to the target location and the predetermined maximum spot size, determine the range of the system's focusing position. Based on the range of the focusing position, calculate the system's equivalent focal length range that can damage the target. This includes the following steps:

[0030] Use the target location as the nearest focal point. According to the predetermined maximum spot size and most recently focused position Calculate the farthest focal position :

[0031]

[0032] In the formula, Given the width of the laser beam emitted by the system, the range of the system's focusing position is obtained. According to the range of the focus position The equivalent focal length range of the calculation system is given by the following formula:

[0033]

[0034] In the formula, D is the equivalent focal length of the system, and F is the focusing position of the laser beam. , and For equivalent focal length in The coefficients for intervals, , and For equivalent focal length in Coefficients for intervals;

[0035] Based on the relationship between equivalent focal length and focal position, the range of focal position is obtained. The corresponding equivalent focal length range;

[0036] S3: Based on the calculated focal length range, the position of the laser emitting eyepiece group is adjusted using a focusing motor so that the focal length value of the system is within the focal length range.

[0037] S4: Use a fiber laser to emit a laser beam, and focus the emitted laser beam to the target position to damage the target.

[0038] The beneficial effects of this application are:

[0039] First, the technical solution in this application employs a transmission-type laser emission system to achieve far-field focusing of the emitted light from a fiber laser. The main working elements are the lenses within the laser emission eyepiece group and the laser emission objective lens group. The eyepiece group includes two concave lenses with opposing concave surfaces, and the objective lens group includes three convex lenses with convex surfaces facing the light emission direction. The width of the eyepiece group is smaller than that of the objective lens group. The two concave lenses increase the beam divergence angle, allowing the beam to propagate uniformly to the objective lens group. The three convex lenses uniformly converge the expanded beam to the target position. This design of first expanding the beam and then focusing improves the far-field quality of the laser beam while avoiding beam divergence. The internal focusing of the laser tube solves the problem of excessive system temperature rise caused by concentrated laser energy, reduces the impact of high temperature on each lens, and improves system stability. In addition, the materials used for each lens are pure fused silica, which has excellent optical performance, giving the laser emission system better thermal stability. The distance between the eyepiece group and the objective lens group in this application ranges from 470mm to 471.5mm, corresponding to a system focusing position range of 2km to 0.3km. The technical solution in this application can achieve the directional focusing function of high-power laser beams at long distances, and can damage distant targets when the average focusing power density reaches the damage threshold.

[0040] In existing reflective laser emission systems, a focal point forms inside the lens barrel during laser transmission, leading to excessively high system temperature due to concentrated laser energy. This reflective laser emission system is highly sensitive to thermal deformation of structural components during laser transmission, exhibiting low temperature stability. When the system temperature rises excessively, it becomes difficult to control focusing accuracy and maintain a continuous and stable focused spot power density at the target location, thus failing to adequately meet the requirements for target destruction within a certain range. In contrast, the technical solution in this application uses a lens to achieve far-field laser focusing. There is no focal point inside the lens barrel during laser transmission, avoiding the problem of excessively high system temperature caused by concentrated laser energy. Furthermore, it maintains a continuous and stable focused spot power density, exhibiting relatively high temperature stability even in harsh environments, and thus possessing significant practical application value.

[0041] Secondly, the laser emission system in this application uses a five-element lens, which has a relatively simple system structure and takes into account factors such as aberration correction and lens axial distance adjustment. The five-element lens reduces manufacturing costs and avoids the problems of scattered light spots and poor light focusing effect. It minimizes the drop in light intensity across the entire field of view and has high overall brightness of the light spot image, which can achieve target damage. The lens material uses the same fused silica material, which improves the stability and transmittance of the system and makes it easy to use. Attached Figure Description

[0042] The advantages of the above and / or additional aspects of this application will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0043] Figure 1 This is a schematic diagram of the overall structure of a transmission-type high-power laser emitting system according to an embodiment of this application;

[0044] Figure 2 This is a schematic diagram of the structure of a laser emitting mirror assembly according to an embodiment of this application;

[0045] Figure 3 This refers to the divergence angle of a transmission-type high-power laser emitting system according to an embodiment of this application;

[0046] Figure 4 This is a wavefront diagram of a transmission high-power laser emitting system according to an embodiment of this application;

[0047] Figure 5 This is a diagram illustrating the effect of physical optics tracing a high-power laser beam focused at a position of 0.3 km according to an embodiment of this application;

[0048] Figure 6 This is a diagram illustrating the effect of physical optics tracing a high-power laser beam focused at a position of 2km, according to an embodiment of this application.

[0049] Among them, 1-laser emitting lens group, 11-laser emitting eyepiece group, 111-first laser emitting eyepiece, 112-second laser emitting eyepiece, 12-laser emitting objective lens group, 121-first laser emitting objective lens, 122-second laser emitting objective lens, 123-third laser emitting objective lens, 2-emitting lens tube, 3-focusing motor, 4-control circuit board. Detailed Implementation

[0050] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0051] In the following description, many specific details are set forth in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0052] like Figures 1 to 2As shown, this embodiment provides a transmissive high-power laser emission system, which includes a laser input end and a laser output end. The laser input end is connected to the output connector of a high-power fiber laser and is used to receive the laser beam emitted by the fiber laser. The laser output end is used to focus the laser beam emitted by the fiber laser to the target position.

[0053] In this embodiment, the end of the transmission-type high-power laser emitting system used to receive the laser is taken as its laser incident end, i.e. Figure 1 The right end of the laser emission system is used to connect to the fiber optic output interface of the fiber laser; the end used to emit laser light in the transmission-type high-power laser emission system is used as its laser emission end. Figure 1 The left end of the laser beam is used to focus the laser beam to a preset target position.

[0054] The transmission-type high-power laser emission system consists of a laser emitting mirror group 1, an emitting mirror tube 2, a focusing motor 3, and a matching control circuit board 4.

[0055] The laser emitting lens group 1 is located inside the emitting lens tube 2. The laser emitting lens group 1 includes a laser emitting eyepiece group 11 and a laser emitting objective lens group 12. The laser emitting eyepiece group 11 is located at the laser incident end inside the emitting lens tube 2, and the laser emitting objective lens group 12 is located at the laser emitting end inside the emitting lens tube 2.

[0056] The laser emitting eyepiece group 11 is used to expand the incident laser beam to increase the divergence angle of the laser beam, so that the laser beam propagates uniformly to the laser emitting objective lens group 12. The laser emitting objective lens group 12 is used to uniformly focus the expanded laser beam to the target position. The diameter of each lens in the laser emitting eyepiece group 11 is smaller than the diameter of each lens in the laser emitting objective lens group 12. The optical path of the laser beam in each lens of the laser emitting objective lens group 1 is as follows: Figure 2 As shown, the laser emitting eyepiece group 11 diffuses the incident laser, increasing the divergence angle of the laser beam and propagating it uniformly to the location of the laser emitting objective lens group 12. The laser emitting objective lens group 12 then uniformly converges the expanded laser beam to the target location.

[0057] The laser emitting eyepiece group 11 consists of a first laser emitting eyepiece 111 and a second laser emitting eyepiece 112, wherein both the first laser emitting eyepiece 111 and the second laser emitting eyepiece 112 are concave lenses, and the concave surfaces of the two concave lenses are arranged adjacent to each other.

[0058] Specifically, the first laser emitting eyepiece 111 and the second laser emitting eyepiece 112 are arranged sequentially according to the optical path direction (the optical path direction is the direction of the laser beam from the incident end to the emitting end). The object side (the side closest to the fiber laser) of the first laser emitting eyepiece 111 is convex, and the image side (the side away from the fiber laser) is concave. That is, the side with the smaller radius of curvature in the first laser emitting eyepiece 111 faces the laser emitting end of the emitting lens tube 2. The object side of the second laser emitting eyepiece 112 is concave, and the image side is flat. That is, the side with the smaller radius of curvature in the second laser emitting eyepiece 112 faces the laser incident end of the emitting lens tube 2.

[0059] The laser emitting objective lens group 12 consists of a first laser emitting objective lens 121, a second laser emitting objective lens 122, and a third laser emitting objective lens 123. The first laser emitting objective lens 121, the second laser emitting objective lens 122, and the third laser emitting objective lens 123 are all convex lenses, and the three convex lenses are arranged in a continuous manner.

[0060] Specifically, the first laser emitting objective lens 121, the second laser emitting objective lens 122, and the third laser emitting objective lens 123 are arranged sequentially according to the optical path direction. The object-side surface of the first laser emitting objective lens 121 is concave, and the image-side surface is convex, that is, the surface with the smaller radius of curvature in the first laser emitting objective lens 121 faces the laser incident end of the emitting lens tube 2; the object-side surface of the second laser emitting objective lens 122 is concave, and the image-side surface is convex, and the surface with the smaller radius of curvature in the second laser emitting objective lens 122 faces the laser incident end of the emitting lens tube 2; the object-side surface of the third laser emitting objective lens 123 is planar, and the image-side surface is convex, and the surface with an infinite radius of curvature (i.e., a planar surface) in the third laser emitting objective lens 123 faces the laser incident end of the emitting lens tube 2, that is, its convex surface faces the laser exit end.

[0061] In this embodiment, the laser emitting eyepiece group 11 can diverge the passing light beam through two concave lenses, increase the diameter of the light beam at the laser emitting objective lens group 12, improve the far-field quality of the laser beam, and at the same time avoid the light beam from focusing inside the emitting lens tube 2, thereby avoiding the problem of excessive system temperature rise caused by concentrated laser energy, reducing the impact of high temperature on each lens, and improving system stability.

[0062] The parameters of the first laser emitting eyepiece 111 are: focal length f = -202 mm; object-side radius of curvature R1 = 500.3 mm; image-side radius of curvature R2 = 77.9 mm (positive values ​​indicate concave surfaces);

[0063] The parameters of the second laser emitting eyepiece 112 are: focal length f = -193mm; object-side radius of curvature R1 = -88.4mm; image-side radius of curvature R2 = infinity (a radius of curvature of infinity means that the side is a plane).

[0064] The parameters of the first laser emitting objective lens 121 are: focal length f = 3292 mm; object-side radius of curvature R1 = -500.3 mm; image-side radius of curvature R2 = -380.9 mm;

[0065] The parameters of the second laser emitting objective 122 are: focal length f = 1796 mm; object-side radius of curvature R1 = -859 mm; image-side radius of curvature R2 = -423.8 mm;

[0066] The parameters of the third laser emitting objective lens 123 are: focal length f = 1355 mm; object-side radius of curvature R1 = infinity; image-side radius of curvature R2 = -621 mm;

[0067] The distance between the first laser emitting eyepiece 111 and the second laser emitting eyepiece 112 is 10 mm; the distance between the first laser emitting objective lens 121 and the second laser emitting objective lens 122 is 8.75 mm; and the distance between the second laser emitting objective lens 122 and the third laser emitting objective lens 123 is 2 mm.

[0068] In this embodiment, all the lens materials are of the same type, including the first laser emitting eyepiece 111, the second laser emitting eyepiece 112, the first laser emitting objective lens 121, the second laser emitting objective lens 122, and the third laser emitting objective lens 123. The refractive index of these lenses is between 1.45 and 1.46.

[0069] The distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12 ranges from 470 mm to 471.5 mm, and the corresponding focusing position of the transmission high-power laser emitting system ranges from 2 km to 300 m. The larger the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12, the closer the focusing position of the transmission high-power laser emitting system is; the smaller the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12, the farther the focusing position of the transmission high-power laser emitting system is.

[0070] In this embodiment, both the first laser emitting eyepiece 111 and the second laser emitting eyepiece 112 are concave lenses, which can increase the divergence angle of the incident laser beam, expand the beam, and make the diverging laser beam uniformly illuminate the laser emitting objective lens group 12. The first laser emitting objective lens 121, the second laser emitting objective lens 122, and the third laser emitting objective lens 123 are all convex lenses, which can focus the diverging laser beam to the target position to form a clear focal point. In this way, expanding the beam through the eyepiece can avoid the problems of unclear focal point and unclear laser spot at the target position caused by the beam being too small. The expanded laser beam has a larger spot size, so that the objective lens can produce a clear focal point when focusing, instead of forming an unclear spot due to excessive beam concentration. The expansion of the laser beam can reduce the spot size and position error during focusing and improve the focusing accuracy.

[0071] Each lens in the laser emitting mirror assembly 1 is made of high-purity fused silica; the specific material can be quartz glass JGS1, Corning 7980, Corning 7979, Ohara low OH value quartz, or other quartz glass of the same grade.

[0072] In the laser emitting mirror assembly 1, each lens is coated with an optical coating material to increase the lens transmittance and reduce the lens reflectance. The coating material can be magnesium fluoride (MgF2), silicon dioxide (SiO2), or calcium fluoride (CaF2), etc., to reduce the impact of reflected light on the focusing quality of the system.

[0073] An aperture stop is provided at the laser incident end of the emitting lens tube 2. The aperture stop is located on the side of the laser emitting eyepiece group 11 near the fiber laser and is set at the exit beam waist of the fiber laser. Setting an aperture stop can prevent other stray light from entering the system from the laser incident end and affecting the focusing quality of the system.

[0074] In this embodiment, the aperture stop in the emitting lens tube 2 is located 40mm away from the side of the laser emitting eyepiece group 11, and the diameter of the aperture stop is set to 33mm.

[0075] In this embodiment, the operating wavelength range of the transmission-type high-power laser emission system is 1080±10nm. The operating wavelength range usually depends on the transmittance and material selection of the optical elements used. The individual lenses made of high-purity fused silica can meet the requirement of an operating wavelength range of 1080±10nm. The laser beam expansion ratio is 6.5 (that is, the diameter / beam width of the input laser beam is magnified by 6.5 times by the transmission-type high-power laser emission system).

[0076] In this embodiment, the laser emitting lens group 1 is a structure composed of a transmissive eyepiece and a transmissive objective lens. Under the control of the focusing motor 3, the transmissive objective lens can move back and forth along the axis inside the emitting lens tube 2 to achieve focusing, so that the transmissive high-power laser emitting system can directionally focus laser beams at different distances.

[0077] The focusing motor 3 is installed on one side of the emitting lens tube 2 near the laser emitting eyepiece group 11. The focusing motor 3 is connected to the laser emitting eyepiece group 11 through a mechanical connector. The focusing motor 3 is used to drive the laser emitting eyepiece group 11 to move back and forth along the axis inside the emitting lens tube 2 through the mechanical connector, thereby changing the relative position between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12, realizing the adjustment of the system focal length, and thus realizing the adjustment of the focusing position of the laser beam.

[0078] In this embodiment, with the distance between the first laser emitting eyepiece 111 and the second laser emitting eyepiece 112, and the distance between the first laser emitting objective lens 121, the second laser emitting objective lens 122 and the third laser emitting objective lens 123 remaining unchanged, the adjustable distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12 is used as the equivalent adjustable focal length of the transmission high-power laser emitting system.

[0079] In this embodiment, the focusing motor 3 can be a stepper motor or a servo motor, etc. The focusing motor 3 can be connected to the laser emitting eyepiece group 11 through mechanical connectors such as screws, lead screws, and gear systems. These mechanical connectors can transmit the rotational motion of the focusing motor 3 to the laser emitting eyepiece group 11, enabling the laser emitting eyepiece group 11 to move. These mechanical connectors all adopt existing structures, such as screw mechanical connectors. The screw is connected to the rotating shaft of the focusing motor 3 through a coupling, while the nut is connected to the laser emitting eyepiece group 11. The motor drives the screw to rotate, which can complete the forward and backward focusing. The lead screw, gear system, and other mechanical connectors are all existing structures and will not be described in detail here.

[0080] The control circuit board 4 is mounted on the emitting lens tube 2 and is electrically connected to the focusing motor 3. The control circuit board 4 is used to receive the focusing input signal and convert the input signal into a motor control command. The motor control command is used to precisely control the rotation of the focusing motor 3 to achieve focusing.

[0081] In this embodiment, the focusing input signal received by the control circuit board 4 comes from the upper-level controller or the user interface. After the user inputs the required focal length, the control circuit board 4 can adjust the focus according to the received focusing input signal.

[0082] The launch tube 2 is also provided with mechanical interfaces for connecting to the external pitch assembly and the observation and aiming assembly. The external pitch assembly and the observation and aiming assembly are fixedly connected to the launch tube 2 through these mechanical interfaces.

[0083] It should be noted that for transmission-type high-power laser emission systems, the following points need to be considered during design and manufacturing: 1) Avoid strong residual reflected laser light returning to the system; 2) Avoid energy-concentrated stray light points inside the lens; 3) The refractive index of the lens material should be uniform and stable, without scratches, with low roughness, and low thermal absorption and thermal expansion coefficients; 4) The material and design of the coating should maximize transmittance; 5) The overall system should have high laser transmittance to reduce light absorption, while dispersing heat to the mechanical housing and performing heat dissipation treatment; 6) Comprehensive consideration should be given to the complexity of processing and assembly, as well as the focusing method and accuracy.

[0084] Based on the above requirements, this embodiment uses high-purity fused silica material to fabricate the lenses in the laser emitting lens assembly 1. High-purity fused silica material has advantages such as a low coefficient of thermal expansion, high thermal conductivity, and small stress deformation. It is not easily deformed when irradiated by laser and can quickly transfer heat energy to the mechanical housing of the system for heat dissipation, which is beneficial to improving the stability of the system. Since the laser spectrum range is relatively narrow (working band is 1080±10nm), the lenses in the laser emitting lens assembly 1 do not need additional chromatic aberration correction and can be made of the same material. Other materials, such as CaF2, can better correct chromatic aberration as positive lenses, but they are very expensive and have a high risk of damage during processing, resulting in waste of expensive materials. K9 material has similar dispersion to fused silica and does not help with chromatic aberration correction. Therefore, this embodiment uses high-purity fused silica material as the material for the lenses in the laser emitting lens assembly 1, which can save costs and improve the high temperature resistance and stability of the system.

[0085] To address the issues of returned laser light and internal stray light, these must be avoided during the design phase, and the lens quality must be inspected after the design is completed. In this embodiment, the laser emitting lens group of the high-power laser emitting system adopts a Galilean structural design. This design avoids wavefront errors caused by air ionization or thermal deflection of light due to internal light focusing. Firstly, to avoid internal stray light, it is necessary to prevent the primary reflection convergence point from being located on the surface or inside of the lens. Specifically, the ghost image of the system should not be focused on the surface or inside of all lenses, but rather on the area between the eyepiece group 11 and the objective lens group 12. This allows heat to be transferred to the outside of the emitting system through a high thermal conductivity housing. Simultaneously, it is necessary to avoid excessive lens power (an optical power threshold can be set to ensure that the optical power of all lenses is less than this threshold). In this embodiment, the above problems can be solved by precisely controlling the curvature parameters and position of each lens when setting them up, thus avoiding the generation of internal stray light. Since the laser power density is highest from the aperture to the eyepiece group, water cooling can be added to the eyepiece group during use. Secondly, regarding the issue of reflected light, on the one hand, materials with high light transmittance and low reflectivity are selected when coating the lens to reduce its reflectivity. On the other hand, collimated or focused reflected light is prevented from reaching the entrance pupil of the system lens. In this embodiment, an aperture stop is set at the entrance pupil of the system lens (i.e., the laser incident end of the emitting lens tube 2), and the aperture stop is set at the exit beam waist of the fiber laser. This can prevent other collimated or focused reflected light from reaching the entrance pupil of the system lens and improve the focusing quality of the system.

[0086] The arrangement of individual lenses in laser emitting lens group 1 improves system stability and transmittance while also considering factors such as aberration correction and lens axial distance. In this embodiment, each lens uses a spherical design. Based on this, the system's aperture and size are set to the minimum within the design limits to control manufacturing costs and weight. Furthermore, spherical lenses offer better surface roughness than aspherical lenses, increasing the lens's damage threshold. A three-element emitting lens has a larger spot dispersion, resulting in approximately a 50% decrease in power density outside the field of view. A four-element design, with minimal changes from a three-element design, optimizes image quality, controls the dispersion area to a smaller region, and reduces the full-field-of-view power density to approximately 70-80%. A five-element design further improves image quality, minimizing aberrations other than chromatic aberration, resulting in a full-field-of-view power density reduction to only about 90% of the axial power density. Increasing the number of lenses further improves image quality but leads to increased costs, transmittance, heat dissipation, and assembly requirements. In this embodiment, a five-element lens is used, which reduces the decrease in power density within the field of view, makes the light intensity distribution more uniform, and simultaneously reduces costs, increases laser transmittance, reduces heat dissipation difficulty, and lowers assembly and adjustment requirements. Since the laser power density is higher at the eyepiece, the number of lenses should be minimized to reduce heat dissipation difficulty; therefore, the eyepiece is set to a two-element lens, and the objective lens is set to a three-element lens.

[0087] Considering the focusing method and accuracy, the focusing amount should not be too large or too small; set the focusing amount to 1.5mm.

[0088] This embodiment also provides an application of a transmission-type high-power laser emission system in achieving target destruction. The transmission-type high-power laser emission system focuses the laser beam to achieve an average power density at the target location that reaches the destruction threshold, thereby achieving target destruction. The specific process is as follows:

[0089] S1: Determine the target location that needs to be damaged, and align the laser output end of the system with the target location;

[0090] The location of the target to be damaged is determined by external detection equipment. Based on the feedback from the observation and aiming components, the position of the transmission-type high-power laser emission system is adjusted by external elevation components so that its laser emission end is aligned with the target position.

[0091] S2: Based on the distance to the target location and the predetermined maximum spot size, determine the range of the system's focusing position. Based on the range of the focusing position, calculate the system's equivalent focal length range that can damage the target. This includes the following steps:

[0092] The distance between the system and the target location is used as the nearest focusing position. According to the predetermined maximum spot size and most recently focused position Calculate the farthest focal position farthest focal position The expression is:

[0093]

[0094] In the formula, The width of the laser beam emitted by the system is given, and the range of the system's focusing position is given. The unit is km.

[0095] In this embodiment, the width of the laser beam emitted by the system can be obtained by measurement (e.g., by using a laser beam analyzer or detector to directly measure the laser beam emitted by the system), and the distance between the system and the target location can be measured by an external distance measuring device.

[0096] According to the range of the focal position The equivalent focal length range of the system is calculated, and the equivalent focal length range of the system is expressed as follows:

[0097]

[0098] In the formula, D is the equivalent focal length of the system (i.e., the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12), and F is the focusing position of the laser beam, with units of km. , and For equivalent focal length in The coefficients for intervals, , and For equivalent focal length in The coefficients for intervals, =1.6667, =-1569.5, =369500.3333, =0.9167, =-864.2, =203684.3708.

[0099] Based on the relationship between equivalent focal length and focal position, the range of the focal position is calculated. The corresponding equivalent focal length range.

[0100] In this embodiment, a predetermined maximum spot size is set. When considering the power of the optical laser, it is necessary to take into account the power of the optical laser. When the power of the optical laser is large, the maximum spot size should be predetermined. When the laser power is relatively large, the predetermined maximum spot size is determined. Relatively small, making the predetermined maximum spot size The corresponding average power density value (power density refers to the power per unit area) is greater than or equal to the damage threshold (i.e., the power density that can cause damage to the target).

[0101] Based on a predetermined average power density value, the maximum laser spot size capable of damaging the target is determined, wherein the predetermined average power density value is greater than or equal to the damage threshold, and the maximum laser spot size is expressed as:

[0102]

[0103] In the formula, The maximum laser spot size (i.e., the width or diameter of the spot) is measured in meters (km), LP is the total power of the laser measured in watts (W), and LPD is the predetermined average power density value. In this embodiment, a circular area is formed by the laser beam irradiating the surface of the target object. The total power LP of the laser can be determined by the specific high-power fiber laser used, and the output power of the high-power fiber laser is the total power of the laser.

[0104] S3: Based on the calculated focal length range, the position of the laser emitting eyepiece group 11 is adjusted by the focusing motor 3 so that the focal length value of the transmission high-power laser emitting system is within the focal length range.

[0105] Specifically, any value within the focal length range is selected as the focal length value. This focal length value is used as the input of the control circuit board 4. The control circuit board 4 controls the focusing motor 3 to adjust the position of the laser emitting eyepiece group 11, thereby adjusting the focal length of the transmission high-power laser emitting system to the focal length value.

[0106] S4: Use a fiber laser to emit a laser beam, and focus the emitted laser beam to the target position to damage the target.

[0107] In this embodiment, the control circuit board 4 of the transmission high-power laser emission system drives the focusing motor 3 to adjust the focal length, so that the size of the laser spot at the target position is smaller than a preset value, thereby making the average power density at the target position reach the damage threshold, so as to achieve the purpose of damaging the target.

[0108] In this embodiment, the transmissive high-power laser emission system can achieve far-field focusing of high-power laser beams at different positions and damage targets by adjusting the position of the laser emission eyepiece group 11 back and forth.

[0109] Example: Using a fiber laser to input high-power laser light, with an input power of 14kW and a working wavelength of 1080 nm, M 2 The factor is approximately 7 (a factor used to measure the spatial coherence and quality of a beam; the M factor for an ideal Gaussian beam is approximately 7). 2 The value is 1, while the actual beam's M is 1.2 >1 indicates that the beam deviates from the ideal Gaussian properties. The beam waist diameter of the input laser is 22mm, and the incident laser divergence angle (i.e., the divergence angle of the laser beam during transmission) is 2. =430µrad, where µrad is a microradian. Based on the relationship between the maximum laser spot size and power density, it can be calculated that the spot size (i.e., the diameter of the spot) needs to be less than 130mm in order for the average power density of the spot to reach the damage threshold.

[0110] Table 1

[0111]

[0112] The transmission-type high-power laser emission system in the application was tested. Focusing was achieved by adjusting the distance between the laser emission eyepiece group 11 and the laser emission objective lens group 12. The distance between the laser emission eyepiece group 11 and the laser emission objective lens group 12 is the equivalent focal length of the system. The correspondence between the equivalent focal length of the system and the focusing position is shown in Table 1.

[0113] As shown in Table 1, when the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12 increases, the focal length increases and the focusing position becomes closer; conversely, when the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12 decreases, the focal length decreases and the focusing position becomes farther. For example, when the distance between the laser emitting eyepiece group 11 and the laser emitting objective lens group 12 is 470mm, the transmission-type high-power laser emitting system achieves focusing of the laser beam at a position of 2km. When the laser emitting eyepiece group 11 is focused 1.5mm away from the laser emitting objective lens group 12, the transmission-type high-power laser emitting system achieves focusing of the laser beam at a position of 0.3km. Setting the focusing amount to 1.5mm balances focusing accuracy and control difficulty.

[0114] The wavefront diagram of the laser emitted by the system is as follows Figure 4 As shown; the divergence angle of the system is as follows: Figure 3 As shown, the divergence angle of the first group of lasers is 0.0000 degrees (DEG), the divergence angle of the second group of lasers is 0.1400 degrees, and the divergence angle of the third group of lasers is 0.2000 degrees.

[0115] Using the transmission-type high-power laser emission system of this application, the laser beam is focused to a predetermined position, and the high-energy laser emitted by the system is simulated using physical optics methods. The simulation results are as follows: Figures 5 to 6 As shown, the physical optics simulation method can better simulate the actual diffusion and energy distribution of the light beam in the far field. Figure 5 To demonstrate the effectiveness of physical optics in tracking a high-power laser beam focused at a position of 0.3 km. Figure 6The figure shows the effect of physical optics on tracking a high-power laser beam focused at a position of 2km. The figure also shows the energy density distribution of the beam at different focusing positions, with the vertical axis representing (V / m). 2 The electric field strength square (the energy density distribution is obtained by summing the square values ​​of the field strength over the entire region) represents the energy distribution of the beam in space. The horizontal axis represents the position coordinates on the cross section in meters, showing the distribution of the beam energy density on that cross section. The beam diameter of the laser at 0.3 km (usually defined as 1 / e of the energy at its maximum) is approximately 40 mm, and the beam diameter at 2 km is approximately 130 mm, which meets the damage requirements.

[0116] The steps in this application can be rearranged, combined, or deleted according to actual needs.

[0117] The units in the device of this application can be merged, divided, and deleted according to actual needs.

[0118] Although this application has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of this application. The scope of protection of this application is defined by the appended claims and may include various variations, modifications, and equivalents of the invention without departing from the scope and spirit of this application.

Claims

1. A transmission-type high-power laser emitting system, characterized in that, The transmission-type high-power laser emission system includes a laser input end and a laser output end. The laser input end is connected to the output connector of a high-power fiber laser and is used to receive the laser beam emitted by the fiber laser. The laser output end is used to focus the laser beam to the target position. The transmissive high-power laser emitting system includes a laser emitting mirror group (1), an emitting mirror tube (2), a focusing motor (3), and a control circuit board (4). The laser emitting lens group (1) is disposed inside the emitting lens tube (2). The laser emitting lens group (1) includes a laser emitting eyepiece group (11) and a laser emitting objective lens group (12). The laser emitting eyepiece group (11) is located at the laser incident end, and the laser emitting objective lens group (12) is located at the laser emitting end. The diameter of the laser emitting eyepiece group (11) is smaller than the diameter of the laser emitting objective lens group (12). The laser emitting eyepiece group (11) includes two concave lenses with their concave surfaces facing each other. The laser emitting eyepiece group (11) is used to expand the incident laser beam to increase the divergence angle of the laser beam, so that the laser beam can be uniformly propagated to the laser emitting objective lens group (12). The laser emitting objective lens group (12) includes three convex lenses, with the convex surfaces of the three convex lenses facing the direction of laser emission. The laser emitting objective lens group (12) is used to uniformly focus the expanded laser beam to the target position. The focusing motor (3) is located on the outside of the emitting lens tube (2) near the laser emitting eyepiece group (11) to adjust the position of the laser emitting eyepiece group (11) in order to achieve system focal length adjustment; The control circuit board (4) is used to receive the focusing input signal and control the focusing motor (3) to focus according to the focusing input signal.

2. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, The laser emitting eyepiece group (11) includes a first laser emitting eyepiece (111) and a second laser emitting eyepiece (112) in sequence along the optical path direction. The object side of the first laser emitting eyepiece (111) is convex with a radius of curvature of 500.3 mm, and the image side of the first laser emitting eyepiece (111) is concave with a radius of curvature of 77.9 mm. The object side of the second laser emitting eyepiece (112) is concave with a radius of curvature of -88.4 mm, while the image side of the second laser emitting eyepiece (112) is flat.

3. The transmission-type high-power laser emitting system as described in claim 2, characterized in that, The focal length of the first laser emitting eyepiece (111) is -202mm, and the focal length of the second laser emitting eyepiece (112) is -193mm; The distance between the first laser emitting eyepiece (111) and the second laser emitting eyepiece (112) is 10 mm.

4. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, The laser emitting objective lens group (12) includes, in sequence along the optical path, a first laser emitting objective lens (121), a second laser emitting objective lens (122), and a third laser emitting objective lens (123). The first laser emitting objective (121) has a concave side surface with a radius of curvature of -500.3 mm and an image side surface with a radius of curvature of -380.9 mm. The second laser emitting objective (122) has a concave side surface with a radius of curvature of -859mm, and the first laser emitting objective (121) has a convex side surface with a radius of curvature of -423.8mm. The object side of the third laser emitting objective (123) is flat, and the image side of the third laser emitting objective (123) is convex with a radius of curvature of -621mm.

5. The transmission-type high-power laser emitting system as described in claim 4, characterized in that, The focal length of the first laser emitting objective (121) is 3292mm, the focal length of the second laser emitting objective (122) is 1796mm, and the focal length of the third laser emitting objective (123) is 1355mm. The distance between the first laser emitting objective (121) and the second laser emitting objective (122) is 8.75 mm; the distance between the second laser emitting objective (122) and the third laser emitting objective (123) is 2 mm.

6. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, The distance between the laser emitting eyepiece group (11) and the laser emitting objective lens group (12) ranges from 470 mm to 471.5 mm, and the corresponding focusing position of the transmission high-power laser emitting system ranges from 2 km to 0.3 km. The larger the distance between the laser emitting eyepiece group (11) and the laser emitting objective lens group (12), the closer the focusing position of the system is; the smaller the distance between the laser emitting eyepiece group (11) and the laser emitting objective lens group (12), the farther the focusing position of the system is.

7. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, The focusing motor (3) is connected to the laser emitting eyepiece group (11) through a mechanical connector. It is used to move the laser emitting eyepiece group (11) through the mechanical connector, change the relative position between the laser emitting eyepiece group (11) and the laser emitting objective lens group (12), and realize the system focal length adjustment. The control circuit board (4) is set on the emitting lens barrel (2) and is electrically connected to the focusing motor (3).

8. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, An aperture stop is provided at the laser incident end, and the aperture stop is located on the side of the laser emitting eyepiece group (11) near the fiber laser.

9. The transmission-type high-power laser emitting system as described in claim 1, characterized in that, Each lens in the laser emitting eyepiece group (11) and the laser emitting objective group (12) is made of the same high-purity fused silica material with a refractive index between 1.45 and 1.

46.

10. An application of a transmission-type high-power laser emission system as described in any one of claims 1-9 in achieving target destruction, characterized in that, The application includes the following steps: S1: Determine the target location that needs to be damaged, and align the laser output end of the system with the target location; S2: Based on the distance to the target location and the predetermined maximum spot size, determine the range of the system's focusing position. Based on the range of the focusing position, calculate the system's equivalent focal length range that can damage the target. This includes the following steps: Use the target location as the nearest focal point. According to the predetermined maximum spot size and most recently focused position Calculate the farthest focal position : ； In the formula, Given the width of the laser beam emitted by the system, the range of the system's focusing position is obtained as follows: According to the range of the focus position The equivalent focal length range of the calculation system is given by the following formula: The relationship between the equivalent focal length and the focal position is: ； In the formula, D is the equivalent focal length of the system, and F is the focusing position of the laser beam. , and For equivalent focal length in The coefficients for intervals, , and For equivalent focal length in Coefficients for intervals; Based on the relationship between equivalent focal length and focal position, the range of focal position is obtained. The corresponding equivalent focal length range; S3: Based on the calculated focal length range, the position of the laser emitting eyepiece group (11) is adjusted by the focusing motor (3) so that the focal length value of the system is within the focal length range. S4: Use a fiber laser to emit a laser beam, and focus the emitted laser beam to the target position to damage the target.

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