Laser beam expanding lens of atmospheric detection laser radar capable of eliminating temperature drift

Abstract

The invention discloses a laser beam expander for an atmospheric detection laser radar capable of eliminating temperature drift, which comprises a beam expander body, an external protective cover, a screw rod arranged in the external protective cover and an adjusting sliding block, and is characterized in that an inclined sliding groove is formed in the beam expander body, the adjusting sliding block is arranged in the inclined sliding groove, and the adjusting sliding block and the screw rod are fixed; according to the invention, the thermal expansion coefficient is matched by setting the angle of the oblique sliding groove, and the first lens module is driven by the oblique sliding block, so that the distance between the first lens and the second lens is adjusted, and the thermal expansion effects of the external protection cover and the screw rod are mutually offset; the simple structure of the laser beam expanding lens is kept, and meanwhile the temperature drift eliminating capacity is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser beam expanders, and particularly relates to a laser beam expander for an atmospheric detection lidar that eliminates temperature drift. Background Art

[0002] A laser beam expander is a laser device that enlarges the laser spot size and simultaneously compresses the laser divergence angle. It is an important tool for improving the quality of laser beams to meet various laser applications and plays an important role in atmospheric detection lidars.

[0003] The laser beam with a high power density, a relatively small spot size, and a large divergence angle generated by the pulsed laser of the atmospheric detection lidar enters the laser beam expander and becomes an outgoing laser beam with a relatively low power density, a large spot size, and a small divergence angle. The laser beam expander usually consists of two front and rear lenses, a support structure, and an adjustment mechanism. The first and second lenses are concentrically installed in the support mechanism. Generally, the second lens is a positive lens. When the first lens is a positive lens, the laser beam expander is of the Kepler type, and the laser beam is first focused and then diverged and collimated into a parallel beam by the second lens. When the first lens is a negative lens, the laser beam expander is of the Galileo type, and there is no laser focus point in the optical path, which is suitable for high-energy occasions. The interval between the two lenses is determined by factors such as the equivalent focal lengths of the first and second lenses and the divergence angle of the incident laser beam. When the divergence angle of the incident laser beam changes, the interval between the two lenses needs to be adjusted by the adjustment mechanism to make it adaptable. Due to the change in ambient temperature and the heat generated during laser transmission, the thermal expansion effect of the support structure will cause the interval between the two lenses to change, resulting in unstable beam expansion effect and temperature drift phenomenon.

[0004] Temperature control of the optical system can reduce the temperature drift problem caused by temperature shock. However, the second lens at the output end of the laser beam expander of the atmospheric detection lidar is usually exposed to the atmospheric environment, making it difficult to carry out reasonable temperature control. Using materials with different coefficients of thermal expansion to form a complex adjustment mechanism composed of multiple-stage sleeves can eliminate a certain amount of temperature drift phenomenon. However, as the number of sleeve levels increases, the laser beam expander becomes very complex, the difficulty of ensuring lens concentricity increases sharply, and the problem of thermal non-uniformity also becomes prominent. An active focusing mechanism is also used in imaging lenses to drive the lens to reduce the temperature drift problem. However, this method requires feedback using the collected images and cannot be applied to the temperature drift elimination control of the laser beam expander of the atmospheric detection lidar. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser beam expander for an atmospheric detection lidar that eliminates temperature drift in view of the above problems existing in the prior art.

[0006] The above object of the present invention is achieved by the following technical means: A laser beam expander for eliminating temperature drift in an atmospheric detection lidar, comprising a beam expander body, an external protective cover, a lead screw disposed within the external protective cover, and an adjustment slider. The beam expander body is disposed within the external protective cover. The beam expander body includes a first lens module and a second lens module that share a central axis. The first lens module is slidably connected to the second lens module. The first lens module is provided with an inclined chute that forms a set angle with the vertical direction. The top of the lead screw is fixedly connected to the top of the external protective cover, and the bottom of the lead screw is suspended. The adjustment slider includes an inclined shift slider and a fixed block. The inclined shift slider is slidably disposed within the inclined chute, and the fixed block is sleeved and fixed on the lead screw. The inclined shift slider is connected to the fixed block.

[0007] As described above, the first lens module includes a first lens barrel and an extension barrel that share a central axis. The inclined chute is disposed on the first lens barrel. The center of the front end face of the first lens barrel is a first light inlet. A first lens lens is installed within the first lens barrel. The rear end of the first lens barrel is fixedly connected to the front end of the extension barrel.

[0008] As described above, the second lens module includes a second lens barrel. A second lens lens is disposed on the second lens barrel. The center of the front end face of the second lens barrel is a connection hole. The rear end of the extension barrel is slidably connected to the connection hole.

[0009] As described above, the set angle between the inclined chute and the vertical direction is calculated based on the following formula: , wherein, is the distance between the first lens lens and the second lens lens, is the vertical length of the portion of the lead screw between the adjustment slider and the top of the external protective cover, is the thermal expansion coefficient of the external protective cover, is the thermal expansion coefficient of the lead screw.

[0010] As described above, the center of the front side face of the external protective cover is provided with an external light inlet, and the center of the rear side face of the external protective cover is provided with an external light outlet.

[0011] As described above, a compression spring is further sleeved on the extension barrel. One end of the compression spring is connected to the first lens barrel, and the other end of the compression spring is connected to the second lens barrel.

[0012] Compared with the prior art, the present invention has the following beneficial effects: By setting the angle of the inclined chute to match the thermal expansion coefficient and using the inclined shift slider to drive the first lens module, the present invention adjusts the distance between the first lens lens and the second lens lens, enabling the thermal expansion effects of the external protective cover and the lead screw to cancel each other out. While maintaining the simple structure of the laser beam expander, it has the ability to eliminate temperature drift. Description of the Drawings

[0013] Figure 1 is a schematic structural diagram of the device of the present invention; Figure 2 is a schematic structural diagram of the lead screw and the adjustment slider in the device of the present invention; Reference numerals and corresponding component names: 1 - External protective cover; 2 - Lead screw; 3 - Adjustment slider; 4 - Oblique chute; 5 - First lens barrel; 6 - First lens; 7 - Second lens barrel; 8 - Second lens; 9 - Fixed block; 10 - Oblique shift slider; 11 - Bearing seat; 12 - Extension tube; 13 - Compression spring. Detailed Description of the Invention

[0014] For the convenience of those of ordinary skill in the art to understand and implement the present invention, the present invention will be further described in detail below in conjunction with embodiments. The embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0015] Embodiment

[0016] A laser beam expander for an atmospheric detection lidar eliminating temperature drift includes a beam expander body, an external protective cover 1, a lead screw 2 arranged in the external protective cover 1, and an adjustment slider 3. The beam expander body is arranged in the external protective cover 1. The beam expander body includes a first lens module and a second lens module with a common central axis. The first lens module and the second lens module are slidably connected. An oblique chute 4 is arranged on the first lens module, and the oblique chute 4 forms a set angle with the vertical direction , the top of the lead screw 2 is fixedly connected to the top of the external protective cover 1, and the bottom of the lead screw 2 is suspended;

[0017] In this embodiment, the adjustment slider 3 includes an oblique shift slider 10 slidably arranged in the oblique chute 4 and a fixed block 9 sleeved and fixed on the lead screw 2. The oblique shift slider 10 and the fixed block 9 are connected as a whole, and the oblique shift slider 10 can slide along the oblique chute 4.

[0018] The first lens module includes a first lens barrel 5 and an extension tube 12 with a common central axis. The oblique chute 4 is arranged on the first lens barrel 5. The center of the front end face of the first lens barrel 5 is a first light inlet, and a first lens 6 is installed in the first lens barrel 5; the rear end of the first lens barrel 5 is fixedly connected to the front end of the extension tube 12 as a whole.

[0019] The second lens module includes a second lens barrel 7. A second lens 8 is arranged on the second lens barrel 7. The center of the front end face of the second lens barrel 7 is a connection hole. The rear end of the extension tube 12 is slidably connected to the connection hole. The first lens barrel 5 can slide along the second lens barrel 7 through the extension tube 12, so as to adjust the distance between the first lens 6 and the second lens 8.

[0020] The front side center of the external protective cover 1 is provided with an external light inlet, and the rear side center of the external protective cover 1 is provided with an external light outlet; A compression spring 13 is also sleeved on the extension cylinder 12. One end of the compression spring 13 is connected to the first lens barrel 5, and the other end of the compression spring 13 is connected to the second lens barrel 7.

[0021] It further includes a bearing seat 11. The bearing seat 11 is fixedly connected to the top surface of the external protective cover 1, and the top end of the lead screw 2 passes through the bearing seat 11 and is fixedly connected to the top surface of the external protective cover 1.

[0022] Set the distance between the first lens 6 and the second lens 8 as , and adjust the vertical length of the part of the lead screw 2 between the adjustment slider 3 and the top of the external protective cover 1 (that is, adjust the distance between the top of the adjustment slider 3 and the top surface of the external protective cover 1) as , when the temperature changes , due to the thermal expansion factor of the external protective cover 1, the distance between the first lens 6 and the second lens 8 is , where is the thermal expansion coefficient of the external protective cover 1; due to the thermal expansion of the lead screw 2, the distance (vertical direction) between the adjustment slider 3 and the top surface of the external protective cover 1 changes to , where is the thermal expansion coefficient of the lead screw 2; the distance that the adjustment slider 3 drives the first lens module to move is , then the total distance change between the first lens 6 and the second lens 8 is is:

[0023] = Formula (1)

[0024] Relative to the traditional method of changing the inherent material property of the thermal expansion coefficient , of the material or modifying the geometric length obtained by restricting the optical path to , to achieve the elimination of , in the present invention, by setting the inclination direction of the oblique chute 4, making , substituting it into the above formula immediately gives , that is, when the temperature changes , the distance between the first lens 6 and the second lens 8 remains unchanged, achieving the effect of eliminating temperature drift.

[0025] It should be noted that the embodiments described in the present invention are only illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described embodiments or use similar ways for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A laser beam expander for an atmospheric detection lidar that eliminates temperature drift, comprising a beam expander body, characterized in that, It further includes an external protective cover (1), a lead screw (2) arranged inside the external protective cover (1), and an adjustment slider (3). The beam expander body is arranged in the external protective cover (1). The beam expander body includes a first lens module and a second lens module with a common central axis. The first lens module is slidably connected to the second lens module. An inclined chute (4) is arranged on the first lens module, and the inclined chute (4) forms a set angle with the vertical direction. The top of the lead screw (2) is fixedly connected to the top of the external protective cover (1), and the bottom of the lead screw (2) is suspended. The adjustment slider (3) includes an inclined shift slider (10) and a fixed block (9). The inclined shift slider (10) is slidably arranged in the inclined chute (4). The fixed block (9) is sleeved and fixed on the lead screw (2), and the inclined shift slider (10) is connected to the fixed block (9).

2. The laser beam expander of the temperature drift elimination atmospheric detection lidar according to claim 1, characterized in that The first lens module includes a first lens barrel (5) and an extension barrel (12) that share a common central axis. An inclined chute (4) is provided on the first lens barrel (5). The center of the front end face of the first lens barrel (5) is a first light inlet. A first lens element (6) is installed in the first lens barrel (5). The rear end of the first lens barrel (5) is fixedly connected to the front end of the extension barrel (12).

3. The laser beam expander of the temperature drift elimination atmospheric detection lidar according to claim 2, characterized in that, The second lens module includes a second lens barrel (7). A second lens element (8) is provided on the second lens barrel (7). The center of the front end face of the second lens barrel (7) is a connection hole. The rear end of the extension barrel (12) is slidably connected to the connection hole.

4. The laser beam expander of an atmospheric detection lidar for eliminating temperature drift according to claim 3, characterized in that, The set angle of the inclined chute (4) with the vertical direction is calculated based on the following formula: ， Wherein, is the distance between the first lens element (6) and the second lens element (8), is the vertical length of the screw rod (2) part between the adjusting slider (3) and the top of the external protective cover (1), is the coefficient of thermal expansion of the external protective cover (1), is the coefficient of thermal expansion of the screw rod (2).

5. The laser beam expander of the temperature drift elimination atmospheric detection lidar according to claim 4, characterized in that The center of the front side of the external protective cover (1) is provided with an external light inlet, and the center of the rear side of the external protective cover (1) is provided with an external light outlet.

6. The laser beam expander of the temperature drift elimination atmospheric detection lidar according to claim 5, characterized in that, A compression spring (13) is also sleeved on the extension barrel (12). One end of the compression spring (13) is connected to the first lens barrel (5), and the other end of the compression spring (13) is connected to the second lens barrel (7).

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