Large aperture optical coaxial linear scanning airborne laser depth sounding radar device

Abstract

The utility model relates to photoelectric signal transmission and detection technical field, concretely relates to a large aperture optical coaxial linear scanning machine -borne laser sounding radar device, including laser emission scanning module, light collection module and optical signal acquisition module, the laser emission scanning module according to beam transfer path includes laser, galvanometer and reflector in proper order, the light collection module according to beam transfer path includes concave mirror, plano -convex lens and convex lens in proper order, the optical signal acquisition module includes polarization module, filter and detector, the utility model discloses can significantly improve the scanning speed of system and the ability of detecting weak signal through galvanometer scanning and cassegrain telescope design, effectively suppresses water surface echo intensity, promotes the characteristic intensity of water bottom echo signal, and the application range is wider.

Description

Technical Field

[0001] This utility model relates to the field of photoelectric signal transmission and detection technology, specifically to a large-aperture optical coaxial linear scanning airborne laser depth sounding radar device. Background Technology

[0002] Airborne laser bathymetry technology is widely used in marine surveying, underwater target detection, and resource exploration. However, traditional systems are limited by small- and medium-diameter optical components and discrete scanning mechanisms, resulting in insufficient detection depth, signal-to-noise ratio, and scanning efficiency. Moreover, traditional devices often employ off-axis designs, which easily introduce parallax errors, leading to a significant decrease in accuracy, especially in shallow water or under high-dynamic low-altitude flight conditions. Simultaneously, the inertia of mechanical scanning mechanisms limits scanning speed, making it difficult to match with high-speed platforms and resulting in uneven strip coverage. Furthermore, environmental disturbances (such as vibration and temperature changes) often cause optical calibration deviations, requiring frequent calibration and limiting long-endurance operation capabilities. Utility Model Content

[0003] In response to the shortcomings of existing technologies, the inventors have developed a large-aperture optical coaxial linear scanning airborne laser depth sounding radar device through long-term practice. By using a common aperture design, parallax is eliminated, shallow water accuracy is improved, efficient and uniform coverage is achieved, and the echo signal is significantly enhanced.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A large-aperture optical coaxial linear scanning airborne laser depth sounding radar device includes a laser emission scanning module, a light collection module, and a light signal acquisition module.

[0006] The laser emission scanning module includes a laser, a galvanometer, and a reflector in sequence according to the beam transmission path. The pulsed laser beam emitted by the laser is incident on the surface of the galvanometer, reflected by the galvanometer, and then incident on the surface of the reflector. After being reflected again by the reflector, it is incident on the surface and bottom of the water being measured.

[0007] The light collection module includes a concave mirror, a plano-convex lens, and a convex lens in sequence according to the beam transmission path. Laser echoes from the water surface and bottom are incident on the surface of the concave mirror, reflected by the concave mirror and converged to the surface of the plano-convex lens, and then reflected again by the plano-convex lens before being focused by the convex lens.

[0008] The optical signal acquisition module includes a polarization module, a narrowband filter, and a photodetector. The focused light rays pass sequentially through the polarization module and the narrowband filter before entering the photodetector.

[0009] Furthermore, the galvanometer is a MEMS micro-galvanometer or a high-speed polyhedral galvanometer.

[0010] Furthermore, the light-collecting module adopts a Cassegrain telescope design with an optical aperture of ≥200 mm.

[0011] Furthermore, the polarization module includes a polarizer, a drive motor, and a speed-changing gear. The rotation angle of the speed-changing gear is adjusted by the drive motor to control the polarization direction of the polarizer.

[0012] Furthermore, the center wavelength of the narrowband filter is 532nm, and the bandwidth is 0.3-1.2nm.

[0013] Furthermore, the photodetector is a single-photon avalanche diode or a linear-mode APD detector.

[0014] Furthermore, the laser emission scanning module and the light collection module are arranged coaxially with the same aperture.

[0015] Furthermore, the device is applicable to drones, fixed-wing aircraft, or helicopter platforms.

[0016] The beneficial effects of this utility model are:

[0017] By employing a large-aperture coaxial optical path design, a galvanometer scanning system, and a Cassegrain telescope structure, the measurement performance of the airborne laser depth sounding radar has been significantly improved.

[0018] 1) The galvanometer enables high-speed scanning at the kHz level, matching the speed of the flight platform and eliminating uneven strip coverage;

[0019] 2) The coaxial optical path design effectively eliminates parallax error in shallow water, and combined with a large aperture telescope of 200mm or more, it greatly enhances the ability to collect weak underwater echoes.

[0020] 3) The polarization module and narrowband filter work together to suppress surface flare and suspended particle scattering noise, improving the signal-to-noise ratio of deep-water signals;

[0021] 4) The overall device is lightweight and low-power, adaptable to diverse platforms such as UAVs, and enables high-precision, high-efficiency, and high-stability long-endurance operations in scenarios such as marine surveying and resource exploration. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the device of this utility model, including the optical path.

[0023] Figure 2 This is a schematic diagram of the structure of the polarization module of this utility model.

[0024] In the attached image:

[0025] 1-Laser, 2-Galvanometer, 3-Reflector, 4-Water surface, 5-Bottom of water, 6-Concave mirror, 7-Planto-convex lens, 8-Convex lens, 9-Polarization module, 10-Narrowband filter, 11-Photodetector, 12-Polarizer, 13-Drive motor, 14-Speed ​​gear. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of this utility model, the technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the scope of this utility model.

[0027] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0028] See Figure 1 and Figure 2 This utility model discloses a large-aperture optical coaxial linear scanning airborne laser depth sounding radar device, which includes a laser emission scanning module, a light collection module, and a light signal acquisition module.

[0029] The laser emission scanning module, according to the beam propagation path, includes a laser 1, a galvanometer 2, and a reflector 3. The pulsed laser beam emitted by the laser 1 is incident on the surface of the galvanometer 2, reflected by the galvanometer 2, and then incident on the surface of the reflector 3. After being reflected again by the reflector 3, the laser beam is incident on the water surface 4 and the water bottom 5, respectively. Depending on the actual measurement requirements, different types of galvanometers can be selected for the galvanometer 2. For low-power, high-resolution depth measurement of UAVs or lightweight airborne platforms, MEMS micro-galvanometers are selected, which are small in size, low in power consumption, fast in scanning speed (up to kHz level), and have no mechanical wear, making them suitable for lightweight systems. For large-area depth measurement requiring high scanning rates, high-speed polyhedral galvanometers are selected.

[0030] The light-collecting module, arranged sequentially according to the beam transmission path, includes a concave mirror 6, a plano-convex lens 7, and a convex lens 8. Laser echoes from the water surface 4 and the seabed 5 are incident on the surface of the concave mirror 6, reflected by the concave mirror 6, and converged onto the surface of the plano-convex lens 7. After further reflection by the plano-convex lens 7, the light is focused by the convex lens 8. This Cassegrain-style telescope design easily achieves large apertures of 200mm and above, significantly improving the collection capability of weak underwater echoes, making it particularly suitable for deep-water exploration. Furthermore, it can be integrated with the laser emission path to achieve coaxial transmission and reception, completely eliminating parallax errors in shallow water areas.

[0031] The optical signal acquisition module consists of a polarization module 9, a narrowband filter 10, and a photodetector 11. After being focused by the convex lens 8, the light passes through the polarization module 9. Water surface reflected light is mostly polarized, while underwater scattered light is unpolarized or partially polarized. The polarization module 9 effectively suppresses surface flare interference by only receiving polarized light that matches the polarization direction of the emitted laser. Furthermore, the polarization characteristics of scattered light from underwater particles (such as plankton and sediment) differ from those of the water body; the polarization module 9 can suppress forward scattering noise and improve the clarity of deep-water signals.

[0032] In this embodiment, the center wavelength of the filter 10 is 532nm and the bandwidth is 0.3-1.2nm; the photodetector 11 is a single-photon avalanche diode or a linear mode APD detector.

[0033] In this embodiment, the laser emission scanning module and the light collection module are set coaxially with the same aperture.

[0034] Considering the different polarization directions of light, the polarization module 9 consists of a polarizer 12, a drive motor 13, and a speed-changing gear 14 to better match the polarized light direction. The drive motor 13 allows for precise adjustment of the rotation angle of the speed-changing gear 14, thereby precisely controlling the polarization direction of the polarizer 12. Light transmitted from the polarizer 12 passes through a narrowband filter 10, which blocks stray light and prevents detector saturation. Finally, the light enters the photodetector 11, where a high-speed collector collects the optical signal and stores it on a hard disk.

[0035] This utility model device is applicable to drones, fixed-wing aircraft or helicopter platforms.

[0036] This invention significantly improves the measurement performance of airborne laser depth sounding radar by employing a large-aperture coaxial optical path design, a galvanometer scanning system, and a Cassegrain telescope structure. The galvanometer (such as a MEMS micro-galvanometer or a high-speed polyhedral galvanometer) achieves kHz-level high-speed scanning, matching the speed of the flight platform and eliminating uneven strip coverage. The coaxial optical path design effectively eliminates shallow water parallax errors, and combined with a large-aperture telescope of 200mm or more, it greatly enhances the ability to collect weak underwater echoes. The polarization module and narrowband filter work together to suppress surface flares and suspended particle scattering noise, improving the signal-to-noise ratio of deep-water signals. The overall system is lightweight and low-power, adaptable to diverse platforms such as UAVs, and enables high-precision, high-efficiency, and high-stability long-endurance operations in scenarios such as marine mapping and resource exploration.

[0037] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of this application should still fall within the scope of the present invention.

Claims

1. A large-aperture optical coaxial linear scanning airborne laser depth sounding radar device, characterized in that, It includes a laser emission scanning module, a light collection module, and a light signal acquisition module; The laser emission scanning module includes a laser (1), a galvanometer (2) and a reflector (3) in sequence according to the beam transmission path; the pulsed laser beam emitted by the laser (1) is incident on the surface of the galvanometer (2), and after being reflected by the galvanometer (2), it is incident on the surface of the reflector (3), and after being reflected by the reflector (3), it is incident on the water surface (4) and the bottom (5) to be measured; The light collection module includes a concave mirror (6), a plano-convex lens (7), and a convex lens (8) in sequence according to the beam transmission path; the laser echoes from the water surface (4) and the bottom (5) are incident on the surface of the concave mirror (6), reflected by the concave mirror (6) and converged to the surface of the plano-convex lens (7), and then reflected by the plano-convex lens (7) and focused by the convex lens (8); The optical signal acquisition module includes a polarization module (9), a narrowband filter (10), and a photodetector (11); the focused light passes through the polarization module (9) and the narrowband filter (10) in sequence before entering the photodetector (11).

2. The apparatus according to claim 1, characterized in that, The galvanometer (2) is a MEMS micro galvanometer or a high-speed polyhedral galvanometer.

3. The apparatus according to claim 1, characterized in that, The light-collecting module adopts a Cassegrain telescope design with an optical aperture of ≥200mm.

4. The apparatus according to claim 1, characterized in that, The polarization module (9) includes a polarizer (12), a drive motor (13), and a speed-changing gear (14). The rotation angle of the speed-changing gear (14) is adjusted by the drive motor (13) to control the polarization direction of the polarizer (12).

5. The apparatus according to claim 1, characterized in that, The center wavelength of the filter (10) is 532nm and the bandwidth is 0.3-1.2nm.

6. The apparatus according to claim 1, characterized in that, The photodetector (11) is a single-photon avalanche diode or a linear mode APD detector.

7. The apparatus according to claim 4, characterized in that, The laser emission scanning module and the light collection module are arranged coaxially with the same aperture.

8. The apparatus according to any one of claims 1-7, characterized in that, The device is suitable for drones, fixed-wing aircraft, or helicopter platforms.

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