A semiconductor laser emission system and method for laser radar

Abstract

The present invention discloses a semiconductor laser emission system and method for laser radar, including the semiconductor laser emission system comprising a laser light source, a reflective prism, a converging lens group, a cylindrical mirror, a homogenizing rod, and a beam expanding lens group; the laser light source is arranged on both sides of the reflective prism, and the laser light source emits at least two light beams, which are combined by the reflective prism; the converging lens group comprises a first lens and a second lens, which converge the combined light beams in sequence; the incident surface of the cylindrical mirror receives the converged light beam, which enters the interior of the homogenizing rod through the exit surface of the cylindrical mirror, undergoes multiple total reflections, and then exits the exit surface, where it is expanded and emitted by the beam expanding lens group. The present invention adjusts the laser divergence angle by designing the lens group structure, thereby forming uniform irradiation light that meets the divergence angle requirements. The homogenizing rod is used to eliminate the coherence of the laser, reduce the speckle effect when imaging the target, and improve the imaging quality.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor laser emission technology, and in particular to a semiconductor laser emission system and method for laser radar. Background Art

[0002] Semiconductor lasers offer advantages such as high electro-optical conversion efficiency, compact size, and light weight, making them increasingly widely used. Single-emission semiconductor lasers cannot achieve extremely high power, so multiple stripe arrays of semiconductor lasers have been stacked to form a planar array laser. Using a planar array semiconductor laser (with a wavelength of 808nm) as a LiDAR light source significantly reduces system size and facilitates subsequent maintenance.

[0003] The shortcomings of existing technology are that this type of semiconductor laser has characteristics such as large spot size, wide divergence angle, and high astigmatism, which limit its further application. Other laser radar systems based on strip array semiconductor lasers are bulky, complex, and difficult to assemble and debug. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology. To achieve the above purpose, a semiconductor laser emission system and method for lidar are adopted to solve the problems raised in the above background technology.

[0005] A technical solution on one hand: a semiconductor laser emitting system for laser radar, the semiconductor laser emitting system comprising a laser light source, a reflecting prism, a converging lens group, a cylindrical mirror, a homogenizing rod, and a beam expanding lens group;

[0006] The laser light source is arranged on both sides of the reflective prism, and the laser light source emits two light beams, which are combined by the reflective prism;

[0007] The converging lens group includes a first lens and a second lens, and the first lens and the second lens converge the combined light beams in sequence;

[0008] The incident surface of the cylindrical mirror receives the converged light beam, which enters the interior of the light homogenizing rod through the exit surface of the cylindrical mirror and undergoes multiple total reflections before exiting the exit surface. The beam is expanded and emitted through the beam expanding lens group.

[0009] As a further solution of the present invention: the laser light source uses two high-power stripe array semiconductor pulse lasers as light sources.

[0010] As a further solution of the present invention: the reflecting prism is an isosceles right-angle prism.

[0011] As a further solution of the present invention: the first lens and the second lens are both spherical lenses.

[0012] As a further solution of the present invention: the incident surface of the cylindrical mirror is a plane, and the exit surface is a concave cylindrical surface.

[0013] As a further solution of the present invention: the beam expanding lens group includes a first beam expanding lens and a second beam expanding lens.

[0014] As a further solution of the present invention: the compression angle range of the divergence angle of the light homogenizing rod and the beam expander lens assembly is 0.01°-1°.

[0015] As a further solution of the present invention: the materials of the reflecting prism, converging lens group, cylindrical mirror, light homogenizing rod, and beam expanding lens group are all made of flint optical glass.

[0016] Another technical solution is a method for a semiconductor laser emission system for a laser radar as described in any one of the above items, the specific steps comprising:

[0017] S1, the laser light source emits two light beams, which are reflected and combined by the two reflecting surfaces of the reflecting prism to obtain a horizontal light beam;

[0018] S2, the horizontal light beam enters the converging lens group for beam reduction, and the beam after beam reduction enters the cylindrical mirror for further beam compression and focusing;

[0019] S3. After the light beam is compressed and focused, it enters the homogenizing rod and undergoes multiple total reflections, resulting in a uniform light spot surface at the end surface of the homogenizing rod. Finally, it is expanded and emitted through the beam expanding lens group.

[0020] As a further solution of the present invention: the sizes of each mirror group of the semiconductor laser emission system are matched and set according to the actual operation conditions of the laser radar.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] The above-mentioned technical solution utilizes a reflective prism with an isosceles right-angle prism structure to focus a high-power bar-array semiconductor pulse laser as the laser light source. A converging lens assembly and cylindrical mirror are used to reduce and focus the beam. A homogenizer rod then performs total reflection homogenization on the reduced and focused beam, eliminating laser coherence and producing a beam that meets the emission angle requirements. The laser light emitted by the bar-array semiconductor laser passes through the transmitting system of the present invention, performing beam combining, shaping, converging, homogenizing, and beam expansion operations to produce laser light that meets the requirements of a lidar system. This reduces speckle effects during target imaging, improving image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0024] Figure 1 A schematic diagram of the overall structure of a semiconductor laser emitting system according to some embodiments disclosed in this application;

[0025] Figure 2 A schematic diagram of the front-end arrangement of a semiconductor laser emission system according to some embodiments disclosed in this application;

[0026] Figure 3 This is a three-dimensional schematic diagram of the front end of the semiconductor laser emitting system of some embodiments disclosed in this application.

[0027] In the figure: 1. Laser light source; 2. Reflecting prism; 3. Converging lens group; 31. First lens; 32. Second lens; 4. Cylindrical mirror; 5. Homogenizer; 6. Beam expanding lens group; 61. First beam expanding mirror; 62. Second beam expanding mirror. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Please refer to Figure 1 In an embodiment of the present invention, a semiconductor laser emitting system for a laser radar includes:

[0030] The semiconductor laser emission system includes a laser light source 1, a reflecting prism 2, a converging lens group 3, a cylindrical mirror 4, a light homogenizing rod 5, and a beam expanding lens group 6;

[0031] In a specific embodiment, the laser light source 1 uses at least two high-power stripe array semiconductor pulse lasers as light sources.

[0032] The laser light source 1 is arranged on both sides of the reflective prism 2. The laser light source 1 emits at least two light beams, which are combined by the reflective prism 2. The reflective prism 2 is an isosceles right-angle prism.

[0033] The converging lens group 3 includes a first lens 31 and a second lens 32, which converge the combined light beams in sequence. Both the first lens 31 and the second lens 32 are spherical lenses.

[0034] The incident surface of the cylindrical mirror 4 receives the converged light beam, enters the interior of the light homogenizing rod 5 through the exit surface of the cylindrical mirror 4, and then exits the exit surface. It then passes through the first beam expander 61 and the second beam expander 62 of the beam expander lens group 6 in turn for beam expansion and emission, obtaining a light beam with a divergence angle compression angle range of 0.7°×0.7°.

[0035] In a specific embodiment, the incident surface of the cylindrical mirror 4 is a plane, and the exit surface is a concave cylindrical surface.

[0036] In a specific embodiment, the beam expanding lens group 6 includes a first beam expanding lens 61 and a second beam expanding lens 62 .

[0037] In a specific embodiment, the compression angle of the divergence angle of the light homogenizing rod 5 and the beam expander lens assembly 6 is in the range of 0.01°-1°. In this embodiment, the compression angle is 0.7°×0.7°.

[0038] In this embodiment, the materials of the reflecting prism, converging lens group, cylindrical mirror, light homogenizing rod, and beam expanding lens group are all flint optical glass.

[0039] Working process:

[0040] like Figure 1 As shown, the figure is a schematic diagram of the overall structure of the semiconductor laser emission system. The light emitted by the laser light source 1 of the bar array semiconductor laser has the disadvantages of large divergence angle and small filling factor. The light emitted by the two lasers is reflected by the two right-angled surfaces of the reflecting prism 2 of the isosceles prism, and enters the first lens 31 and the second lens 32 (composed of two spherical mirrors) of the converging lens group 3 horizontally to complete the reduction of the light spot. Because the single laser light source 1 is strip-shaped, adjusting the relative positions of the two lasers in the Z direction can make the light spots of the two lasers in the far field complementary and overlapping, thereby improving the filling factor of the synthetic light. The laser light passing through the converging lens group 3 enters the cylindrical mirror 4 with a flat incident surface and a concave cylindrical exit surface, compressing the size in the y direction, so that the size of the light spot is smaller than the cross-section of the homogenizer 5, and is focused and incident on the homogenizer 5. The light is totally reflected in the homogenizer 5, which conforms to the law of total reflection. Using the mirror image method, light undergoes multiple total reflections within the homogenizer rod 5 before reaching the exit section. Each reflection is equivalent to the illumination of a mirrored virtual light source. Ultimately, the end surface of the homogenizer rod 5 forms a uniform light spot. The beam expander lens assembly 6, connected to the end, adjusts the laser divergence angle, resulting in a uniform illumination light with a divergence angle of 0.7° × 0.7°. Using the homogenizer rod 5 for light homogenization also eliminates laser coherence, thereby reducing speckle effects and improving image quality when imaging the target.

[0041] Another technical solution is a method for a semiconductor laser emission system for a laser radar as described in any one of the above items, the specific steps comprising:

[0042] S1, the laser light source 1 emits at least two light beams, which are reflected and combined by the two reflecting surfaces of the reflecting prism 2 to obtain horizontal light beams;

[0043] S2, the horizontal light beam enters the converging lens group 3 for beam reduction, and the reduced light beam enters the cylindrical mirror 4 for further beam compression and focusing;

[0044] S3, after the light beam is compressed and focused, it enters the light homogenizing rod 5 and undergoes multiple total reflections, resulting in a uniform light spot surface at the end surface of the light homogenizing rod 5, and finally is expanded and emitted through the beam expanding lens group 6.

[0045] In this embodiment, the sizes of each mirror group of the semiconductor laser emission system can be matched and set according to the actual operation conditions of the laser radar.

[0046] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents, and all should be included within the scope of protection of the present invention.

Claims

1. A semiconductor laser emitting system for laser radar, characterized in that: The semiconductor laser emission system comprises a laser light source (1), a reflecting prism (2), a converging lens group (3), a cylindrical mirror (4), a light homogenizing rod (5), and a beam expanding lens group (6); The laser light source is arranged on both sides of the reflective prism, and the laser light source emits two light beams, which are combined by the reflective prism; The converging lens group comprises a first lens (31) and a second lens (32), and the first lens and the second lens converge the combined light beams in sequence; The incident surface of the cylindrical mirror receives the converged light beam, which enters the interior of the light homogenizing rod through the exit surface of the cylindrical mirror and undergoes multiple total reflections before exiting the exit surface. The beam is expanded and emitted through the beam expanding lens group.

2. A semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The laser light source uses at least two high-power stripe array semiconductor pulse lasers as light sources.

3. A semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The reflecting prism is an isosceles right-angle prism.

4. A semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The first lens and the second lens are both spherical lenses.

5. The semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The incident surface of the cylindrical mirror is a plane, and the exit surface is a concave cylindrical surface.

6. The semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The beam expanding lens group comprises a first beam expanding lens (61) and a second beam expanding lens (62).

7. The semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The compression angle range of the divergence angle of the light homogenizing rod and the beam expander lens assembly is 0.01°-1°.

8. The semiconductor laser emitting system for laser radar according to claim 1, characterized in that: The materials of the reflecting prism, converging lens group, cylindrical mirror, light homogenizing rod, and beam expanding lens group are all made of flint optical glass.

9. A method of using a semiconductor laser emitting system for laser radar according to any one of claims 1 to 8, characterized in that: The specific steps include: S1, the laser light source emits two light beams, which are reflected and combined by the two reflecting surfaces of the reflecting prism to obtain a horizontal light beam; S2, the horizontal light beam enters the converging lens group for beam reduction, and the beam after reduction enters the cylindrical mirror for further beam compression and focusing; S3. After the light beam is compressed and focused, it enters the homogenizing rod and undergoes multiple total reflections, resulting in a uniform light spot surface at the end surface of the homogenizing rod. Finally, it is expanded and emitted through the beam expanding lens group.

10. The method of a semiconductor laser emitting system for laser radar according to claim 9, characterized in that: The sizes of each mirror group of the semiconductor laser emission system are matched and set according to the actual operation of the laser radar.

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