Airborne high-resolution, high-dynamic-range dual-wavelength array lidar for land and water detection

Abstract

This invention discloses an airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for water and land detection, comprising: a dual-band laser, a transmitting unit, a dual-band DOE group, a beam combining unit, a beam scanning unit, a receiving unit, a beam splitting unit, a dual-band detector group, information processing and storage, and a system control unit. This invention fully utilizes the characteristics of strong echoes from water surfaces, shallow water areas, and land. A narrow field of view is achieved using an area array detection method, effectively averaging the amplitude of strong echo signals. A high-response area array detector is selected to fully utilize echo energy while simultaneously improving the system's spatial resolution. Blue-green lasers are used for water body detection, and near-infrared lasers are used for water surface detection. Three-dimensional imaging of the water surface area array helps improve the accuracy of underwater data processing using blue-green lasers.

Description

Technical Field

[0001] This invention belongs to the field of airborne optoelectronic imaging technology and relates to an airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for land and water detection. Background Technology

[0002] For water-bearing and land-bearing areas such as islands, reefs, and coastal zones, there is a strong demand for integrated land-sea detection sensors. Traditional marine lidar employs wide and narrow field-of-view methods to improve the dynamic range of water detection. In shallow water areas, it uses unit detectors with lower responsivity or reduced unit detector gain, while in deep water areas, it uses unit detectors with high responsivity or high gain to meet the detection requirements of strong echoes in shallow water and weak echoes in deep water. However, it does not fully utilize the strong echo energy of water surfaces, shallow water areas, and land. To ensure the density of seabed laser footprints, single-point scanning limits the speed of airborne platforms, resulting in low operational efficiency. Furthermore, land detection requires high point density and high resolution. Integrated land-sea detection lidar faces the challenge of multi-domain, large dynamic echo detection across land, water surfaces, shallow water areas, and deep water areas, as well as high-resolution land-sea detection. Summary of the Invention

[0003] (I) Purpose of the Invention

[0004] The purpose of this invention is to provide an airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for land and water detection, which solves the problems of large dynamic range of signals and high-resolution three-dimensional imaging in the process of integrated land and water detection.

[0005] (II) Technical Solution

[0006] To address the aforementioned technical problems, this invention provides an airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for land and water detection, comprising: a dual-band laser, a transmitting unit, a dual-band DOE group, a beam combiner unit, a beam scanning unit, a receiving unit, a beam splitter unit, a dual-band detector group, information processing and storage, and a system control unit; the dual-band laser synchronously and independently outputs dual-band laser pulses in the blue-green and near-infrared bands; the transmitting unit performs independent collimation of the dual-band lasers; the dual-band DOE group forms a spatial sub-beam distribution consistent with the spatial distribution of the detectors; the beam combiner unit... The system adjusts the spatial distribution of the dual-wavelength sub-beam array to achieve overlap of sub-beams in each band, enabling coaxial transmission; the scanning unit scans the array beams, expanding the field of view for Earth detection; the receiving unit performs dual-band common-aperture reception, achieving narrow field of view reception in shallow water and on land, and wide field of view reception in deep water; the beam splitting unit splits the received beam into blue-green band beams and near-infrared band beams; the dual-band detector group receives the split dual-band beams separately; information processing and storage complete the processing of distance and intensity information; and the system control module completes the synchronous output of dual-band lasers and data clock synchronization.

[0007] (III) Beneficial Effects

[0008] The airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for water and land detection provided by the above technical solution fully utilizes the characteristics of strong echoes from water surfaces, shallow water areas, and land. The narrow field of view employs area array detection to effectively average the amplitude of strong echo signals. A high-response area array detector is selected to fully utilize echo energy while improving the system's spatial resolution. Blue-green lasers are used for water body detection, while near-infrared lasers are used for water surface detection. Three-dimensional imaging of the water surface area array helps improve the accuracy of underwater data processing using blue-green lasers. To achieve deeper water depth detection, a stronger green laser is required, which is generally acquired using near-infrared laser frequency doubling. Therefore, a significant amount of near-infrared laser energy is retained, enabling dual-band area array detection without increasing system power consumption. Attached Figure Description

[0009] Figure 1 This is a block diagram illustrating the composition principle of the airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for land and water detection according to the present invention.

[0010] Figure 2 This is an optomechanical diagram of the airborne high-resolution, high-dynamic-range dual-wavelength area array lidar for land and water detection according to the present invention. Detailed Implementation

[0011] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0012] Figure 1 This is a diagram of the airborne high-resolution, high-dynamic-range dual-wavelength array lidar system for land and water detection of the present invention. It mainly includes: a dual-band laser, a transmitting unit, a dual-band DOE group, a beam combining unit, a beam scanning unit, a receiving unit, a beam splitting unit, a dual-band detector group, information processing and storage, and a system control unit.

[0013] The dual-band laser described above synchronously and independently outputs dual-band laser pulses in the blue-green and near-infrared bands;

[0014] The aforementioned transmitting unit completes independent collimation of dual-band lasers;

[0015] The aforementioned dual-band DOE group forms a spatial sub-beam distribution consistent with the spatial distribution of the detector; the sub-beam arrays are 8×8@532nm and 8×8@1064nm.

[0016] The beam combining unit adjusts the spatial distribution of the dual-wavelength sub-beam array to achieve the overlap of sub-beams in each band and realize coaxial transmission.

[0017] The scanning unit completes the scanning of the array beam, expands the field of view for earth detection, and adopts a prism conical scanning method.

[0018] The receiving unit described above completes dual-band common aperture reception, enabling narrow field of view reception in shallow water and on land, and wide field of view reception in deep water.

[0019] The beam splitting unit uses a dichroic beam splitter.

[0020] The aforementioned dual-band detector array employs a planar detector for narrow field of view, either a single-photon planar detector or a linear planar detector. The 1064nm wavelength uses a Si-APD planar detector, the 532nm wavelength uses an MCP-PMT planar detector, and the large field of view uses a large target surface unit detector. The 532nm deep-water channel uses a PMT unit detector.

[0021] The aforementioned information processing and storage completes the processing of distance and intensity information.

[0022] The system control module described above enables simultaneous output of dual-band lasers and synchronization of data clock.

[0023] Figure 2 This is a simplified optical-mechanical diagram of the system, showing the details of the lidar.

[0024] Among them, the dual-band laser synchronously and independently outputs 532nm and 1064nm dual-band laser pulses.

[0025] The transmitting unit includes two sets of laser collimating lenses, which collimate dual-band laser pulses of 532nm and 1064nm respectively.

[0026] The dual-band DOE group consists of two DOE groups, each of which is arranged on the output side of a laser collimating lens.

[0027] The beam combining unit includes two folding mirrors, which are respectively arranged behind the two sets of DOEs. The 532nm laser pulse corresponds to the first folding mirror, and the 1064nm laser pulse corresponds to the second folding mirror. The first folding mirror reflects the 532nm laser pulse to the second folding mirror, and the second folding mirror reflects the 1064nm laser pulse and transmits the 532nm laser pulse. After combining the two laser pulses, the direction is changed to illuminate the target.

[0028] The beam splitting unit includes two dichroic beam splitters, which split the received beam into a 1064nm band beam and a 532nm band beam. After passing through the corresponding focusing lenses, the beams are received by the corresponding detectors.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An airborne high-resolution large-dynamic-range water-land detection dual-wavelength planar array lidar, characterized in that, It comprises: a dual-band laser, a transmitting unit, a dual-band DOE group, a beam combining unit, a beam scanning unit, a receiving unit, a beam splitting unit, a dual-band detector group, an information processing and storage unit, and a system control unit; the dual-band laser synchronously and independently outputs blue-green band and near-infrared band dual-band laser pulses; the transmitting unit completes independent collimation of the dual-band laser; the dual-band DOE group forms a spatial sub-beam distribution consistent with the spatial distribution of the dual-band detector group; the beam combining unit adjusts the spatial distribution of the dual-band sub-beam array, realizes the coincidence of each band sub-beam, and realizes coaxial emission; the beam scanning unit completes scanning of the array beam, and expands the ground detection field of view; the receiving unit completes dual-band common-aperture reception, and realizes shallow water and land narrow field of view and deep water wide field of view reception; the beam splitting unit splits the received beam into a blue-green band beam and a near-infrared band beam; the dual-band detector group receives the split dual-band beams respectively; the information processing and storage unit completes distance and intensity information processing; and the system control unit completes synchronous output of the dual-band laser and data clock synchronization. The dual-band laser synchronously and independently outputs 532 nm and 1064 nm dual-band laser pulses. The transmitting unit comprises two groups of laser collimating lenses, which collimate the 532 nm and 1064 nm dual-band laser pulses respectively; the dual-band DOE group comprises two groups of DOEs, each group of DOEs being arranged on the light-emitting side of a laser collimating lens. The beam combining unit comprises two folding mirrors, which are arranged on the rear side of the two groups of DOEs; the 532 nm laser pulses correspond to the first folding mirror, and the 1064 nm laser pulses correspond to the second folding mirror; the first folding mirror reflects the 532 nm laser pulses to the second folding mirror; the second folding mirror reflects the 1064 nm laser pulses and transmits the 532 nm laser pulses, combines the two-band laser pulses, and changes the direction of irradiation of the target; The scanning unit adopts a prism conical scanning mode. The beam splitting unit comprises two dichroic mirrors, which split the received beam into a 1064 nm band beam and a 532 nm band beam, and the beams are received by corresponding detectors after passing through corresponding condenser lenses.

2. The airborne high-resolution large-dynamic-range water-land-detection dual-wavelength planar array lidar according to claim 1, characterized in that, In the dual-band detector group, a narrow field of view adopts a face array detector, a single-photon face array or linear face array detector, and a large field of view adopts a large target face unit detector.

3. The airborne high resolution large dynamic range land and water detection dual wavelength area array lidar according to claim 2, wherein, In the dual-band detector group, under a narrow field of view, 1064 nm adopts a Si-APD face array detector, and 532 nm adopts a MCP-PMT face array detector.

4. The airborne high resolution large dynamic range land and water detection dual wavelength area array lidar according to claim 3, wherein, In the dual-band detector group, under a large field of view, 532 nm deep water channel adopts a PMT unit detector.

5. An airborne photo-optical imaging system characterized by, The airborne high-resolution large-dynamic water-land detection dual-wavelength face array laser radar comprises the airborne high-resolution large-dynamic water-land detection dual-wavelength face array laser radar according to any one of claims 1-4.

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