A laser beam expander for eliminating temperature drift in atmospheric detection lidar

Abstract

The present invention discloses a laser beam expander for an atmospheric detection laser radar capable of eliminating temperature drift, comprising a beam expander body, an external protective cover, a lead screw arranged in the external protective cover, and an adjusting slider. An oblique groove is provided on the beam expander body, an adjusting slider is provided in the oblique groove, and the adjusting slider is fixed to the lead screw. The present invention matches the thermal expansion coefficient by setting the angle of the oblique groove, and adopts an oblique sliding slider to drive the first lens module, thereby adjusting the distance between the first lens lens and the second lens lens, so that the thermal expansion effects of the external protective cover and the lead screw offset each other, thereby maintaining the simple structure of the laser beam expander while having the ability to eliminate temperature drift.

Description

Technical Field

[0001] The invention belongs to the technical field of laser beam expanders, and in particular relates to a laser beam expander for eliminating temperature drift of an atmospheric detection laser radar. Background Art

[0002] A laser beam expander is a laser device that expands the laser spot size while compressing 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 lidar.

[0003] The pulsed laser generated by an atmospheric sounding lidar generates a high-power-density, relatively small-spot-size, and wide-divergence laser beam. Upon entering a laser beam expander, it transforms into an outgoing laser beam with relatively low power-density, large-spot-size, and narrow-divergence angle. A laser beam expander typically consists of two front and rear lenses, a support structure, and an adjustment mechanism. The first and second lenses are concentrically mounted within the support mechanism. Typically, the second lens is a positive lens. When the first lens is positive, the laser beam expander is a Keplerian-type system, where the laser beam is first focused and then diverged before being collimated into a parallel beam by the second lens. When the first lens is negative, the laser beam expander is a Galilean-type system, where there is no laser focal point in the optical path, making it suitable for high-energy applications. The spacing 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 spacing between the two lenses requires an adjustment mechanism to adjust to match. Due to changes in ambient temperature and heat generated during laser transmission, the thermal expansion effect of the support mechanism can cause the spacing between the two lenses to change, resulting in unstable beam expansion and temperature drift.

[0004] Temperature control of the optical system can reduce the problem of temperature drift caused by temperature shock, but 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 reasonably control the temperature. Using materials with different thermal expansion coefficients to make a complex adjustment mechanism composed of multi-stage sleeves can eliminate certain temperature drift phenomena. However, as the number of sleeve levels increases, the laser beam expander becomes very complex, and the difficulty of ensuring the concentricity of the lens increases dramatically. At the same time, the problem of thermal imbalance also becomes prominent. In the imaging lens, an active focusing mechanism is also used to drive the lens to reduce the temperature drift problem. However, this method requires the use of collected images for feedback and is not suitable for the temperature drift 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 atmospheric detection laser radar which eliminates temperature drift in order to solve the above problems in the prior art.

[0006] The above-mentioned purpose of the present invention is achieved by the following technical means:

[0007] A laser beam expander for eliminating temperature drift of an atmospheric detection laser radar comprises a beam expander body, an external protective cover, a screw arranged in the external protective cover, and an adjustment slider. The beam expander body is arranged in the external protective cover. The beam expander body comprises a first lens module and a second lens module having a common central axis. The first lens module and the second lens module are slidably connected. An oblique slide groove is provided on the first lens module, and the oblique slide groove forms a set angle with the vertical direction. The top of the screw rod is fixedly connected to the top of the external protective cover, the bottom of the screw rod is suspended in the air, the adjustment slider includes an oblique slider and a fixed block, the oblique slider is slidably set in the oblique slide groove, the fixed block is sleeved and fixed on the screw rod, and the oblique slider is connected to the fixed block.

[0008] As described above, the first lens module includes a first lens barrel and an extension barrel with a common central axis, an oblique slide groove is provided on the first lens barrel, the center of the front end surface of the first lens barrel is a first light inlet, a first lens lens is installed in the first lens barrel, and the rear end of the first lens barrel is fixedly connected to the front end of the extension barrel.

[0009] As described above, the second lens module includes a second lens barrel, on which a second lens plate is provided. The center of the front end surface of the second lens barrel is a connecting hole, and the rear end of the extension barrel is slidably connected to the connecting hole.

[0010] As mentioned above, the setting angle between the inclined chute and the vertical direction Calculated based on the following formula:

[0011] ,

[0012] Where, is the distance between the first lens and the second lens, To adjust the vertical length of the screw rod between the slider and the top of the external protective cover, is the thermal expansion coefficient of the outer protective cover, is the thermal expansion coefficient of the screw.

[0013] As mentioned above, the center of the front side of the external protective cover is provided with an external light inlet, and the center of the rear side of the external protective cover is provided with an external light outlet.

[0014] As mentioned above, a compression spring is also sleeved on the extension tube, 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.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention matches the thermal expansion coefficient by setting the angle of the oblique slide groove and uses an oblique slider to drive the first lens module, thereby adjusting the distance between the first lens lens and the second lens lens, so that the thermal expansion effects of the external protective cover and the lead screw offset each other, maintaining the simple structure of the laser beam expander while having the ability to eliminate temperature drift. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0018] Figure 2 Schematic diagram of the structure of the screw rod and the adjustment slider in the device of the present invention;

[0019] Reference numerals and corresponding component names:

[0020] 1-External protective cover; 2-Screw rod; 3-Adjusting slider; 4-Oblique slide groove; 5-First lens barrel; 6-First lens lens; 7-Second lens barrel; 8-Second lens lens; 9-Fixed block; 10-Oblique slider; 11-Bearing seat; 12-Extension tube; 13-Compression spring. DETAILED DESCRIPTION

[0021] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below with reference to the embodiments. The embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0022] Example

[0023] A laser beam expander for eliminating temperature drift of an atmospheric detection laser radar comprises a beam expander body, an external protective cover 1, a screw 2 disposed in the external protective cover 1, and an adjustment slider 3. The beam expander body is disposed in the external protective cover 1 and comprises a first lens module and a second lens module having a common central axis. The first lens module and the second lens module are slidably connected. An oblique slide groove 4 is provided on the first lens module, and the oblique slide groove 4 forms a set angle with the vertical direction. , the top of the screw rod 2 is fixedly connected to the top of the external protective cover 1, and the bottom of the screw rod 2 is suspended;

[0024] In this embodiment, the adjustment slider 3 includes an oblique slider 10 slidingly arranged in the oblique slide groove 4 and a fixed block 9 sleeved and fixed on the screw rod 2. The oblique slider 10 is connected to the fixed block 9 as a whole, and the oblique slider 10 can slide along the oblique slide groove 4.

[0025] The first lens module includes a first lens barrel 5 and an extension barrel 12 with a common central axis. An oblique slide groove 4 is provided on the first lens barrel 5. The center of the front end surface 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 as a whole.

[0026] The second lens module includes a second lens barrel 7, on which a second lens element 8 is provided. The center of the front end surface of the second lens barrel 7 is a connecting hole, and the rear end of the extension barrel 12 is slidably connected to the connecting hole. The first lens barrel 5 can slide along the second lens barrel 7 through the extension barrel 12, thereby adjusting the distance between the first lens element 6 and the second lens element 8.

[0027] An external light inlet is provided at the center of the front side of the external protective cover 1, and an external light outlet is provided at the center of the rear side of the external protective cover 1;

[0028] A compression spring 13 is sleeved on the extension tube 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 .

[0029] It also includes a bearing seat 11, which is fixedly connected to the top surface of the external protective cover 1, and the top end of the screw rod 2 passes through the bearing seat 11 and is fixedly connected to the top surface of the external protective cover 1.

[0030] Set the distance between the first lens 6 and the second lens 8 to , adjust the vertical length of the screw rod 2 between the slider 3 and the top of the external protective cover 1 (that is, adjust the distance between the top of the slider 3 and the top surface of the external protective cover 1) to , when the temperature changes When the thermal expansion factor of the external protective cover 1 causes the distance between the first lens 6 and the second lens 8 to be ,in, is the thermal expansion coefficient of the external protective cover 1; due to the thermal expansion of the screw 2, the distance (vertical direction) between the adjustment slider 3 and the top surface of the external protective cover 1 changes to ,in, is the thermal expansion coefficient of the screw 2; the distance that the slider 3 drives the first lens module to move is , then the total distance between the first lens 6 and the second lens 8 changes for:

[0031] = Formula (1)

[0032] Compared with the traditional method of changing the thermal expansion coefficient of the material , The inherent material properties or the geometric length obtained by modifying the optical path to constrain , to achieve elimination The present invention sets the inclined direction of the inclined chute 4 so that , substituting into the above formula, we can immediately get , that is, temperature change When the distance between the first lens 6 and the second lens 8 is unchanged, achieving the effect of eliminating temperature drift.

[0033] It should be noted that the embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A laser beam expander for eliminating temperature drift of an atmospheric detection laser radar, comprising a beam expander body, characterized in that: The invention also includes an external protective cover (1), a screw rod (2) arranged in the external protective cover (1), and an adjusting slider (3); the collimator body is arranged in the external protective cover (1); the collimator 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 oblique sliding groove (4) is provided on the first lens module; the oblique sliding groove (4) is at a set angle to the vertical direction The top of the screw rod (2) is fixedly connected to the top of the external protective cover (1), the bottom of the screw rod (2) is suspended in the air, the adjustment slider (3) includes an oblique sliding slider (10) and a fixed block (9), the oblique sliding slider (10) is slidably set in the oblique sliding groove (4), the fixed block (9) is sleeved and fixed on the screw rod (2), and the oblique sliding slider (10) is connected to the fixed block (9); It also 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 screw rod (2) passes through the bearing seat (11) and is fixedly connected to the top surface of the external protective cover (1). The first lens module comprises a first lens barrel (5) and an extension barrel (12) having a common central axis, an oblique slide groove (4) is provided on the first lens barrel (5), the center of the front end surface of the first lens barrel (5) is a first light inlet, a first lens lens (6) is installed in the first lens barrel (5), and the rear end of the first lens barrel (5) is fixedly connected to the front end of the extension barrel (12). The second lens module comprises a second lens barrel (7), a second lens lens (8) is provided on the second lens barrel (7), the center of the front end surface of the second lens barrel (7) is a connecting hole, and the rear end of the extension barrel (12) is slidably connected to the connecting hole. The setting angle of the oblique slide (4) and the vertical direction Calculated based on the following formula: ， Where, is the distance between the first lens (6) and the second lens (8), To adjust the vertical length of the screw rod (2) between the slider (3) and the top of the outer protective cover (1), is the thermal expansion coefficient of the outer protective cover (1), is the thermal expansion coefficient of the screw (2).

2. The laser beam expander for eliminating temperature drift of atmospheric detection laser radar according to claim 1, characterized in that: An external light inlet is provided at the center of the front side of the external protective cover (1), and an external light outlet is provided at the center of the rear side of the external protective cover (1).

3. The laser beam expander for eliminating temperature drift of atmospheric detection laser radar according to claim 2, characterized in that: A compression spring (13) is also sleeved on the extension tube (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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