An airborne large-field-of-view high-precision laser detection capability enhancement device

Abstract

The present invention relates to an airborne, large-field-of-view, high-precision laser detection capability enhancement device. The present invention uses a large-array linear APD as a laser detector and arranges a two-dimensional deflection liquid crystal optical phased array in each laser transceiver channel. The polarization characteristics of the liquid crystal optical phased array match the polarization state of the transceiver light beam, achieving large-scale electronically controlled scanning without a mechanical structure and improving the laser scanning speed. Then, through an image stitching algorithm, several 64×64 laser images are stitched into a high-resolution laser image, improving the imaging quality and real-time performance of laser three-dimensional imaging. In addition, the deflection angle of the optical phased array can be changed accordingly according to different needs to obtain images with different resolutions.

Description

Technical Field

[0001] The present invention belongs to the field of laser detection and relates to an airborne large-field-of-view high-precision laser detection capability enhancement device. Background Art

[0002] Airborne three-dimensional laser imaging radars are widely used in ground reconnaissance, concealed target identification, terrain mapping, and collision avoidance. Due to the size limitations of APD arrays, current laser radars often use mechanical scanning to improve detection resolution, resulting in slow scanning speeds, low imaging resolution, and poor real-time performance. To enhance the imaging capabilities of airborne laser radars, enabling rapid, high-resolution scanning over large areas, it is necessary to design an airborne, high-precision laser detection capability enhancement device with a large field of view. Summary of the Invention

[0003] Technical problems to be solved

[0004] In order to avoid the shortcomings of the existing technology, the present invention proposes an airborne large-field-of-view, high-precision laser detection capability enhancement device, which adopts a large-array linear APD as a laser detector and arranges a two-dimensional deflection liquid crystal optical phased array in each laser transceiver channel. The polarization characteristics of the liquid crystal optical phased array match the polarization state of the transceiver light beam, realizing large-scale electronically controlled scanning without a mechanical structure. Then, through the image stitching algorithm, high-resolution laser images are obtained, thereby improving the imaging quality and real-time performance of laser three-dimensional imaging.

[0005] Technical Solution

[0006] An airborne large-field-of-view, high-precision laser detection capability enhancement device is characterized by an eye-safe laser 1, a laser collimator 2, a Dammann grating 3, a first liquid crystal optical phased array 4, a polarization beam splitter 5, a 1 / 4λ wave plate 6, a transmitting and receiving optical lens 7, a second liquid crystal optical phased array 8, a large-area linear APD detector 9, and an image processing module 10. The laser beam of the eye-safe laser 1 passes through the laser collimator 2 and the Dammann grating 3 in sequence and is shaped into a uniform array light. After entering the first liquid crystal optical phased array 4, the array light is incident on a polarization common aperture isolation unit composed of a polarization beam splitter 5 and a 1 / 4λ wave plate 6, and then passes through an optical lens 7 to be emitted into a target space. The laser echo signal enters the optical lens 7 and the polarization common aperture isolation unit, passes through the polarization beam splitter 5 therein, and is injected into the second liquid crystal optical phased array 8, deflecting echoes in different directions onto the large-area linear APD detector 9. The output signal of the large-area linear APD detector is input into the image processing module 10.

[0007] The eye-safe laser 1 is a 1570nm eye-safe laser. It uses a laser diode to pump Nd:YAG laser electro-optical Q-switching to convert 1.06μm pump light into eye-safe 1.57μm linearly polarized light through KTP nonlinear frequency conversion. The laser frequency is not less than 1000Hz.

[0008] The Dammann grating 3 adopts a 64×64 Dammann grating with a diffraction efficiency of not less than 95%. After shaping, a 64×64 uniform array light is obtained.

[0009] The large-area linear APD detector 9 adopts a 64×64 large-area linear APD detector, a microlens array is packaged on the detector surface, and the detection sensitivity of the detector is not less than 1nw.

[0010] The image processing module 10 performs data noise reduction on the three-dimensional data point cloud of the laser echo to filter out various noises mixed in the laser three-dimensional imaging data; then aligns and splices the laser point cloud data acquired at different scanning angles to form a large-field-of-view high-resolution laser image.

[0011] The first liquid crystal optical phased array 4 and the second liquid crystal optical phased array 8 are two-dimensional liquid crystal optical phased arrays, which can control the deflection of the light beam in the X and Y directions. The energy transmission rate of a single phased array is not less than 90%, the deflection accuracy is not greater than 10μrad, and the response time is not greater than 10ms.

[0012] The polarization beam splitter 5 has a transmission efficiency of not less than 95%, a reflection efficiency of not less than 99.5%, and an extinction ratio of not less than 2000:1.

[0013] The effective aperture of the 1 / 4λ wave plate 6 is greater than 95%, and the reflection parameter is less than 0.1%.

[0014] According to actual needs, the scanning range is adjusted by controlling the deflection angle of the phased array to obtain images with different resolutions.

[0015] Beneficial effects

[0016] The present invention proposes an airborne, large-field-of-view, high-precision laser detection capability enhancement device, which uses a large-array linear APD as a laser detector and arranges a two-dimensional deflected liquid crystal optical phased array in each laser transceiver channel. The polarization characteristics of the liquid crystal optical phased array match the polarization state of the transceiver beam, realizing large-scale electronically controlled scanning without a mechanical structure, improving the laser scanning speed, and then using an image stitching algorithm to stitch several 64×64 laser images into a high-resolution laser image, improving the imaging quality and real-time performance of laser three-dimensional imaging. In addition, the deflection angle of the optical phased array can be changed accordingly according to different needs to obtain images of different resolutions.

[0017] The advantages of the present invention are: an airborne large-field-of-view, high-precision laser detection capability enhancement device is invented, which is used in conjunction with a two-dimensional liquid crystal optical phased array and a large-area linear APD. It has no mechanical structure and good airborne reliability. While greatly improving the laser imaging resolution, it can still meet the needs of airborne real-time imaging, improve the imaging performance of airborne laser radar, and can change the deflection angle of the optical phased array according to different needs to obtain images with different resolutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of an airborne large-field-of-view high-precision laser detection capability enhancement device.

[0019] in:

[0020] 1- Eye-safe laser, 2- Laser collimator, 3- Dammann grating, 4- Liquid crystal optical phased array, 5- Polarization beam splitter, 6- 1 / 4λ wave plate, 7- Transmitting and receiving optical lenses, 8- Liquid crystal optical phased array, 9- Large-area linear APD detector, 10- Image processing module.

[0021] Figure 2 This is a schematic diagram of image stitching DETAILED DESCRIPTION

[0022] The present invention will now be further described with reference to the embodiments and accompanying drawings:

[0023] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of an airborne, large-field-of-view, high-precision laser detection capability enhancement device. In this embodiment, the airborne, large-field-of-view, high-precision laser detection capability enhancement device comprises: an eye-safe laser 1, a laser collimator 2, a Dammann grating 3, a liquid crystal optical phased array 4, a polarization beamsplitter 5, a ¼λ wave plate 6, transmitting and receiving optical lenses 7, a liquid crystal optical phased array 8, a large-area linear APD 9, and an image processing module 10.

[0024] Wherein: the eye-safe laser 1 is a 1570nm eye-safe laser, which uses a laser diode to pump Nd:YAG laser electro-optical Q-switching to convert 1.06μm pump light into eye-safe 1.57μm linearly polarized light through KTP nonlinear frequency conversion, and the laser frequency is not less than 1000Hz.

[0025] The Dammann grating 3 is a 64×64 diffraction spectrometer element, and the diffraction efficiency is not less than 95%.

[0026] The liquid crystal optical phased array 4 and the liquid crystal optical phased array 8 are two-dimensional liquid crystal optical phased arrays that can control the deflection of the light beam in the X and Y directions. The energy transmission rate of a single phased array is not less than 90%, the deflection accuracy is not greater than 10μrad, and the response time is not greater than 10ms.

[0027] The polarization beam splitter 5 and the 1 / 4λ wave plate 6 constitute a polarization isolation unit. The polarization beam splitter 5 has a transmission efficiency of not less than 95%, a reflection efficiency of not less than 99.5%, and an extinction ratio of not less than 2000:1. The effective aperture of the 1 / 4λ wave plate 6 is greater than 95%, and the reflection parameter is less than 0.1%.

[0028] Large area array linear APD9 is a 64×64 large area array linear APD detector with a micro lens array encapsulated on the detector surface. The detector detection sensitivity is not less than 1nw.

[0029] Eye-safe laser 1 is a 1570nm eye-safe laser. It uses a laser diode-pumped Nd:YAG laser electro-optically Q-switched to convert 1.06μm pump light into eye-safe 1.57μm linearly polarized light through KTP nonlinear frequency conversion. The laser frequency is no less than 1000Hz. The emitted laser passes through a laser collimator 2 and a 64×64 Dammann grating 3, where the beam is shaped into a 64×64 uniform array. The array then enters a two-dimensional liquid crystal optical phased array 4. Driven by voltage, the array can control the beam deflection in both the X and Y directions, allowing for varying angles depending on imaging requirements. Because the liquid crystal phased array is polarization-sensitive, a polarization common-aperture isolation unit consisting of a polarization beamsplitter 5 and a quarter-λ wave plate 6 is used to ensure consistent laser transmission and reception fields of view. After passing through the polarization isolation unit, the laser beam passes through an optical lens 7 and is emitted into the target space.

[0030] After entering the optical lens, the laser echo signal passes through a polarization isolation unit and enters a two-dimensional liquid crystal optical phased array 8. The optical phased array deflects the echoes in different directions onto a large 64×64 linear APD detector 9. To improve echo energy utilization and prevent interference from scattered echoes, a microlens array is encapsulated on the detector surface to converge the laser echo onto the surface of each pixel.

[0031] The image processing steps of the image processing module 10 are as follows:

[0032] Step 1: Perform data denoising on the 3D data point cloud of the laser echo to filter out various noises mixed in the laser 3D imaging data;

[0033] Step 2: Align and stitch the laser point cloud data acquired at different scanning angles into a large-field-of-view, high-resolution laser image.

[0034] The output signal of the large-area linear APD detector enters the image processing module 10. The image processing module first performs data noise reduction on the three-dimensional data point cloud of the laser echo to filter out various noises mixed in the laser three-dimensional imaging data; then the laser point cloud data acquired at different scanning angles are aligned and spliced ​​to form a large-field-of-view high-resolution laser image, such as Figure 2 As shown, the scanning range can be adjusted by controlling the deflection angle of the phased array according to actual needs to obtain images with different resolutions.

Claims

1. An airborne large field of view high precision laser detection capability enhancement device, characterized in that Eye-safe laser (1), laser collimator (2), Dammann grating (3), first liquid crystal optical phased array (4), polarization beam splitter (5), 1 / 4λ wave plate (6), transmitting and receiving optical lens (7), second liquid crystal optical phased array (8), large-area linear APD detector (9) and image processing module (10); the laser beam of the eye-safe laser (1) passes through the laser collimator (2) and the Dammann grating (3) in sequence and is shaped into a uniform array light, the array light enters the first liquid crystal optical phased array (4) and is incident on the polarization common aperture isolation unit composed of the polarization beam splitter (5) and the 1 / 4λ wave plate (6), and then passes through the optical lens (7) and is emitted to the target space; the laser echo signal enters the optical lens (7) and the polarization common aperture isolation unit, passes through the polarization beam splitter (5) therein and is injected into the second liquid crystal optical phased array (8), deflecting the echoes in different directions to the large-area linear APD detector (9), the large-area linear APD detector The output signal is input into the image processing module (10); the Dammann grating (3) adopts a 64×64 Dammann grating, the diffraction efficiency of which is not less than 95%, and a 64×64 uniform array light is obtained after shaping; the large-area linear APD detector (9) adopts a 64×64 large-area linear APD detector, the surface of which is encapsulated with a microlens array, and the detection sensitivity of the detector is not less than 1nw; the image processing module (10) performs data noise reduction on the three-dimensional data point cloud of the laser echo, and filters out various noises mixed in the laser three-dimensional imaging data; then the laser point cloud data obtained at different scanning angles are aligned and spliced ​​to form a large-field high-resolution laser image; the first liquid crystal optical phased array (4) and the second liquid crystal optical phased array (8) are two-dimensional liquid crystal optical phased arrays, which can control the deflection of the light beam in the X and Y directions, the energy transmission rate of a single phased array is not less than 90%, the deflection accuracy is not greater than 10μrad, and the response time is not greater than 10ms.

2. The airborne large-field-of-view high-precision laser detection capability enhancement device according to claim 1 is characterized in that: The eye-safe laser (1) is a 1570nm eye-safe laser, which uses a laser diode to pump an Nd:YAG laser electro-optically Q-switched to convert 1.06μm pump light into eye-safe 1.57μm linearly polarized light through KTP nonlinear frequency conversion, and the laser frequency is not less than 1000Hz.

3. The airborne large-field-of-view high-precision laser detection capability enhancement device according to claim 1 is characterized in that: The polarization beam splitter (5) has a transmission efficiency of not less than 95%, a reflection efficiency of not less than 99.5%, and an extinction ratio of not less than 2000:

1.

4. The airborne large-field-of-view, high-precision laser detection capability enhancement device according to claim 1 is characterized in that: The effective aperture of the 1 / 4λ wave plate (6) is greater than 95%, and the reflection parameter is less than 0.1%.

5. The airborne large-field-of-view high-precision laser detection capability enhancement device according to claim 1 is characterized in that: The scanning range is adjusted by controlling the deflection angle of the phased array to obtain images with different resolutions.

Images