A long-range beam homogenizing shaping device for a streak tube lidar

Abstract

A long-distance beam homogenization shaping device for a streak tube laser radar relates to the technical field of laser beam shaping. A laser emits original incident laser, a collimation and expansion lens group is composed of negative lenses and positive lenses arranged in sequence along an optical path, performs collimation and expansion processing on a light beam, and outputs parallel light beams. A beam homogenization shaping module includes two groups of cylindrical microlens arrays and a random phase plate. The two groups of cylindrical microlens arrays divide the incident parallel light beams into multiple sub-beams. The random phase plate applies random phase modulation to the wavefront of the incident sub-beams. After phase modulation, a line light spot is formed on a receiving plane at a distance of 500 m. Through the collimation and expansion lens group cooperating with the double-row cylindrical microlens array, the shaping and expansion of the laser beam in a single direction are realized. Meanwhile, the random phase plate is introduced into the optical path, which significantly suppresses the formation of interference fringes, and can meet the output requirements of a long-distance, large-size, high-uniformity flat-top line light spot.

Description

Technical Field

[0001] This invention relates to the field of laser beam shaping technology, specifically a long-range beam homogenization and shaping device for stripe tube lidar. Background Technology

[0002] As a high-precision laser detection device, the quality of the emitted beam spot in a stripe tube lidar system directly determines the accuracy and reliability of the detection data. In existing stripe tube lidar systems, the conventionally emitted beam spot suffers from uneven intensity distribution. This uneven beam spot directly leads to a decrease in the signal-to-noise ratio of the echo signal, significantly reducing the quality of the acquired data and affecting the detection accuracy of the lidar system.

[0003] Current laser beam homogenization technologies mostly only achieve homogenization of small-sized line spots under short-distance transmission conditions, failing to meet the application requirements of stripe tube lidar for large-sized, highly uniform line spots in long-distance detection scenarios. Therefore, developing a laser homogenization and shaping device capable of obtaining large-sized, highly uniform line spots at long distances has significant engineering application value for improving the detection performance of stripe tube lidar. Summary of the Invention

[0004] To overcome the shortcomings of existing laser homogenization technologies in meeting the homogenization requirements of large-size line spots over long distances, this invention provides a long-range beam homogenization and shaping device for stripe tube lidar. It achieves beam shaping and expansion of the laser beam in one direction by using a collimating and expanding lens group in conjunction with a double-row cylindrical microlens array. At the same time, a random phase plate is introduced into the optical path to significantly suppress the formation of interference fringes, thus meeting the output requirements of large-size, high-uniformity flat-top line spots over long distances.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a long-range beam homogenization and shaping device for stripe tube lidar, which includes a laser, a collimating and expanding lens group and a beam homogenization and shaping module in sequence along the propagation path of the laser.

[0006] The collimating and beam-expanding lens group consists of negative lenses and positive lenses arranged sequentially along the optical path. The beam homogenization and shaping module includes two sets of cylindrical microlens arrays and a random phase plate. The two sets of cylindrical microlens arrays have the same structural parameters and are placed coaxially aligned. The curved surface of the first cylindrical microlens array faces the collimating and beam-expanding lens group in front, and the curved surface of the second cylindrical microlens array faces the receiving plane in the rear. The random phase plate is disposed on the light-emitting side of the second cylindrical microlens array.

[0007] The laser emits the original incident laser beam. The collimating and beam-expanding lens group expands and collimates the laser beam emitted by the laser and outputs a parallel beam. Two sets of cylindrical microlens arrays divide the incident parallel beam into multiple sub-beams, realizing beam shaping and expansion in one direction. A random phase plate applies randomized phase modulation to the wavefront of the incident sub-beams to destroy the coherence of the laser beam and thus suppress the formation of interference fringes. The phase-modulated multiple sub-beams can be superimposed on the receiving plane at a distance of 500m to form a line spot.

[0008] Furthermore, the laser is an Nd:YAG laser, which emits a laser with a center wavelength of 532nm and an initial spot diameter of 3mm.

[0009] Furthermore, in the collimating and expanding lens group, the focal length of the negative lens is -50mm, the focal length of the positive lens is 75mm, and the output beam is adjusted to be parallel light by adjusting the distance between the negative lens and the positive lens, and the beam spot diameter is 4mm.

[0010] Furthermore, the overall dimensions of the cylindrical microlens array are 10mm×10mm×1mm. The aperture of a single cylindrical sub-lens in the cylindrical microlens array is 500um, and the radius of curvature is 1.578mm. Each set of cylindrical microlens arrays consists of 20 cylindrical sub-lenses with the same structural parameters arranged side by side. The spacing between two sets of cylindrical microlens arrays is 3mm.

[0011] Furthermore, the random phase plate is a binary random phase plate, placed 3mm from the light-emitting side of the second cylindrical microlens array, with an overall size of 10mm×10mm×1mm and a size of 0.1mm×0.1mm for a single pixel unit. A binary phase transition of 0 or π is introduced between adjacent pixel units, and the etching depths of the pixel units are 0um and 0.578um, respectively.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention achieves beam shaping and expansion of the laser beam in one direction by using a collimating and beam expanding lens group in conjunction with a double-row cylindrical microlens array. At the same time, by introducing a random phase plate in the optical path, randomized phase modulation is applied to the laser wavefront, effectively destroying the coherence of the laser beam and breaking the interference conditions. This can significantly suppress the formation of interference fringes, and ultimately obtain a large-size, highly uniform flat-top line spot at a distance of 500m. This meets the application requirements of striped tube lidar transmitting systems for long-distance uniformized line spots and effectively improves the quality of data acquired by striped tube lidar. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the optical path structure of the device of the present invention;

[0014] Figure 2This is a three-dimensional structural diagram of the cylindrical microlens array in the device of the present invention;

[0015] Figure 3 This is a schematic diagram of the structure of the random phase plate in the device of the present invention;

[0016] Figure 4 This is a schematic diagram of the line spot obtained on the receiving plane after homogenization by the device of the present invention;

[0017] Figure 5 This is a graph showing the intensity distribution of the linear light spot in the vertical direction after homogenization by the device of the present invention.

[0018] In the diagram: 1. Laser; 2. Collimating and expanding lens group; 3. Beam homogenization and shaping module. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] A long-range beam homogenization and shaping device for stripe laser radar, whose overall optical path structure combines Figure 1 As shown, the laser propagation path sequentially includes a laser 1, a collimating and expanding lens group 2, and a beam homogenization and shaping module 3. The resulting homogenized beam is incident on a detector surface (receiving plane) 500m away from the light-emitting surface of the beam homogenization and shaping module 3, forming a large-sized homogenized line spot.

[0021] The laser 1 is an Nd:YAG laser that emits a Gaussian beam with a center wavelength of 532nm and an initial spot diameter of about 3mm, providing the original incident laser for the entire device.

[0022] The collimating and expanding lens group 2 is composed of a negative lens and a positive lens arranged sequentially along the optical path. The focal length of the negative lens is -50mm, and the focal length of the positive lens is 75mm. The negative lens is located near the light outlet of the laser 1, and the positive lens is located on the light outlet side of the negative lens. By adjusting the distance between the negative lens and the positive lens, the beam emitted from the collimating and expanding lens group 2 is ensured to be approximately parallel, and the beam spot diameter after collimation and expansion is approximately 4mm, providing a parallel incident beam that meets the requirements for subsequent shaping and homogenization processing.

[0023] The beam homogenization and shaping module 3 includes, along the optical path, a first cylindrical microlens array, a second cylindrical microlens array, and a random phase plate. The structural parameters of the first and second cylindrical microlens arrays are identical, differing only in the orientation of their curved surfaces. Combined with... Figure 2 As shown, the overall dimensions of a single cylindrical microlens array are 10mm × 10mm × 1mm, and the array thickness is 1mm. The aperture of a single cylindrical sub-lens in the cylindrical microlens array is 500um, and the radius of curvature of the cylindrical sub-lens is 1.578mm. The single cylindrical microlens array is composed of 20 cylindrical sub-lenses with identical structural parameters, arranged side by side in the horizontal direction. The first cylindrical microlens array and the second cylindrical microlens array are placed parallel and coaxially aligned, with their sub-lens units corresponding one-to-one. However, the curved surface of the first cylindrical microlens array faces forward to collimate and expand the beam lens group 2, while the curved surface of the second cylindrical microlens array faces backward to the receiving plane. The spacing between the two sets of cylindrical microlens arrays is set to 3mm, and the whole array is placed on the light-emitting side of the collimating and expanding beam lens group 2.

[0024] The random phase plate is a binary random phase plate, and its structure combines... Figure 3 As shown, a binary phase transition of 0 or π can be introduced between adjacent pixel units; the overall dimensions of the random phase plate are 10mm×10mm and the thickness is 1mm, the size of a single pixel unit is 0.1mm×0.1mm, and the etching depths of different pixel units are 0um and 0.578um, respectively, thereby realizing binary phase modulation; the random phase plate is placed 3mm away from the light-emitting side of the second cylindrical microlens array.

[0025] The present invention relates to a detection surface for receiving the final homogenized line spot, which is positioned 500m away from the light-emitting surface of the random phase plate, corresponding to the long-range detection scenario of a stripe tube lidar. The working process is as follows:

[0026] The Gaussian beam emitted by laser 1 is first incident on collimating and beam-expanding lens group 2. After diverging by a negative lens, it is then converged and collimated by a positive lens, outputting a parallel beam with a spot diameter of approximately 4 mm. The collimated parallel beam is then incident on the first cylindrical microlens array of beam homogenization and shaping module 3. The laser beam is split into multiple sub-beams by multiple cylindrical sub-lenses on the array. These sub-beams are then incident on the corresponding cylindrical sub-lenses of the second cylindrical microlens array. After further shaping by the second cylindrical microlens array, the beam is expanded in the vertical direction. After initial homogenization, the sub-beams, shaped by two sets of cylindrical microlens arrays, are incident on a random phase plate. The random phase plate applies randomized phase modulation to the laser wavefront of each sub-beam, disrupting the coherence of the laser beam and breaking the interference conditions between multiple beams, thereby effectively suppressing the formation of interference fringes when superimposed in the far field. The homogenized beam, after phase modulation by the random phase plate, continues to propagate forward and is eventually incident on the detection surface at 500m. The multiple sub-beams are superimposed on the receiving plane, thus obtaining a large-size homogenized line spot on the far-distance receiving plane.

[0027] After being shaped and homogenized by the device of the present invention, the line spot obtained by the receiving plane is combined Figure 4 As shown, its vertical light intensity distribution curve is combined with Figure 5 As shown, it can achieve unidirectional flat-top light output with good uniformity of light intensity distribution, meeting the usage requirements of stripe tube lidar transmitting system.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0029] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A long-range beam homogenization and shaping device for stripe laser radar, characterized in that: The laser propagation path includes, in sequence, a laser (1), a collimating and beam expanding lens group (2), and a beam homogenization and shaping module (3). The collimating and beam-expanding lens group (2) consists of negative lenses and positive lenses arranged sequentially along the optical path. The beam homogenization and shaping module (3) includes two sets of cylindrical microlens arrays and a random phase plate. The two sets of cylindrical microlens arrays have the same structural parameters and are placed coaxially aligned. The curved surface of the first cylindrical microlens array faces the collimating and beam-expanding lens group (2) in front, and the curved surface of the second cylindrical microlens array faces the receiving plane in the rear. The random phase plate is set on the light-emitting side of the second cylindrical microlens array. The laser (1) emits the original incident laser. The collimating and beam-expanding lens group (2) expands and collimates the laser beam emitted by the laser (1) and outputs a parallel beam. Two sets of cylindrical microlens arrays divide the incident parallel beam into multiple sub-beams to achieve beam shaping and expansion in a single direction. The random phase plate applies randomized phase modulation to the wavefront of the incident sub-beams to destroy the coherence of the laser beam and thus suppress the formation of interference fringes. The multiple sub-beams after phase modulation can be superimposed on the receiving plane at a distance of 500m to form a line spot.

2. The long-range beam homogenization and shaping device for stripe tube lidar according to claim 1, characterized in that: The laser (1) is an Nd:YAG laser, which emits a laser with a center wavelength of 532nm and an initial spot diameter of 3mm.

3. The long-range beam homogenization and shaping device for stripe tube lidar according to claim 1, characterized in that: In the collimating and expanding lens group (2), the focal length of the negative lens is -50mm and the focal length of the positive lens is 75mm. The output beam is adjusted to be parallel by adjusting the distance between the negative lens and the positive lens, and the beam spot diameter is 4mm.

4. The long-range beam homogenization and shaping device for stripe tube lidar according to claim 1, characterized in that: The overall dimensions of the cylindrical microlens array are 10mm×10mm×1mm. The aperture of a single cylindrical sub-lens in the cylindrical microlens array is 500um, and the radius of curvature is 1.578mm. Each set of cylindrical microlens arrays consists of 20 cylindrical sub-lenses with the same structural parameters arranged side by side. The spacing between two sets of cylindrical microlens arrays is 3mm.

5. A long-range beam homogenization and shaping device for stripe tube lidar according to claim 1, characterized in that: The random phase plate is a binary random phase plate, placed 3mm from the light-emitting side of the second cylindrical microlens array. The overall dimensions are 10mm×10mm×1mm, and the size of a single pixel unit is 0.1mm×0.1mm. A binary phase transition of 0 or π is introduced between adjacent pixel units, and the etching depths of the pixel units are 0um and 0.578um, respectively.

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