A long-distance, high-efficiency "cat’s-eye" target laser active detection method based on the characteristics of target echo spectral segments was proposed. Considering the target echo generation condition, multiple sets of different wavebands, high-frequency and short-pulse detection lasers are used to obtain the high-precision distance value of the detection target, and simultaneously record the echo intensity information of the detection signal for different spectral segments. Analyze the relationship between the target distance, the target feature, the probe band and the beam quality, correlate the distance with the spectrum information, calculate and identify whether the target is a "cat’s eye" target. In the experiment, 1064nm and 1550nm laser sources are used to detect and analyze different types of targets. The test results show that the detection method can quickly and effectively obtain the multi-spectral echo reflection characteristics of the target, and achieve the "Cat’s Eye" target detection in the kilometer range. Effectively reducing the number required for target identifies feature points, improves the recognition efficiency and accuracy, and reduces false alarms.
Online 3-D laser-scanner is a non-contact measurement system with high speed, high precision and easy operation, which can be used to measure heavy and high-temperature forgings. But the current online laser measurement system is mainly a mobile light indicator, which can only be used in the limited environment and lacks the capability of 3-D accurate measurement. This paper mainly introduces the structure of the online high-speed real-time 3-D measurement for heavy high-temperature forgings of Academy of Opto-Electronics (AOE), Chinese Academy of Sciences. Combining TOF pulse distance measurement with hybrid scan mode, the system can scan and acquire point cloud data of an area of 20m×10m with a 75°×40° field of view at the distance of 20m. The entire scanning time is less than 5 seconds with an accuracy of 8mm, which can meet the online dimensional measurement requirements of heavy high-temperature forgings.
The use of CCD imaging to measure laser divergence angle and imaging spot quality directly affect the accuracy of measurement results. Analysis of laser spot imaging features, do noise reduction and desaturation process for the image. With the method of image coordinate vectors superposition to obtain the laser intensity distribution curve in x, y direction, and laser spot diameter is exactly calculated by curve fitting algorithm. Experiment for different exposure intensity spot images, this method is effective to suppress the influence of CCD self-noise and improve measurement accuracy. Different exposure intensity spot images obtained a high measurement accuracy results, and laser divergence angle measurement results with an accuracy higher than 0.01mrad.
Hyperspectral LiDAR using supercontinuum laser as light source, applying spectroscopic technology gets backscattered reflectance of different wavelengths, and can acquire both the geometry and spectral information on the target. Due to the development of the photoelectric sensor, hyperspectral LiDAR has fewer spectral channels, which limits its application in physical properties detection. To solve this problem, this paper proposes a new method based on the micro mirror array. By blaze grating, the supercontinuum laser is grating into monochromatic light in space, first projected to the micro mirror array, by controlling the micro mirror array flip, specific spectrum and reflection to corresponding photoelectric sensor channels, improve the spectral resolution. The micro mirror array photoelectric sensor resolution is much higher than the number of channels, through this method, can greatly improve the spectral resolution. In this paper, based on the micro mirror array, the simulation design is carried out and the feasibility of the method is verified by experiments. The simulation and experimental results show that the spectral resolution can be improved greatly by controlling the turning of the micro mirror.
A 16-channal front-end preamplifier array has been design in a 0.18um CMOS process for pulse Laser ranging radar receiver. This front-end preamplifier array incorporates transimpedance amplifiers(TIAs) and differential voltage post-amplifier(PAMP),band gap reference and other interface circuits. In the circuit design, the regulated cascade (RGC) input stage, Cherry-Hooper and active inductor peaking were employed to enhance the bandwidth. And in the layout design, by applying the layout isolation structure combined with P+ guard-ring(PGR), N+ guard-ring(NGR),and deep-n-well(DNW) for amplifier array, the crosstalk and the substrate noise coupling was reduced effectively. The simulations show that a single channel receiver front-end preamplifier achieves 95 dBΩ transimpedance gain and 600MHz bandwidth for 3 PF photodiode capacitance. The total power of 16-channel front-end amplifier array is about 800mW for 1.8V supply.
Hyperspectral Lidar using supercontinuum laser as light source, applying spectroscopic technology gets backscattered reflectance of different wavelengths, and can acquire both the geometry and spectral information on the target. In the vegetation detection by using Hyperspectral Lidar, through refusing 3d and spectral data, we can get the physical structure and biochemical parameter such as vegetation index, chlorophyll content. This paper constructs a simulating scene including an atmosphere, vegetation and ground surface, simulates spectral waveform of different input conditions such as varying ground reflectance, sloped versus flat ground, and comparisons of "leaf-on" and "leaf-off" conditions. First, using fractal method, the vegetation model was established. Second, applying Monte Carlo method, the laser between vegetation was traced. Third, using the PROSPECT model, established the vegetation spectral reflectance model. Last, by combining of the above three models, built hyperspectral Lidar vegetation detection model, and carry out simulation model under a variety of conditions supply.
An integrated multi-channel receiver for a pulsed time-of-flight (TOF) laser rangefinder has been designed in this paper. The receiver chip as an important component of the laser radar device has been implemented in a 0.18um CMOS process. It consists of sixteen channels and every channel includes preamplifier, amplifier stages, high-pass filter and a timing discriminator which contains a timing comparator and a noise comparator. Each signal paths is independent of other channels. Based on the simulations, the bandwidth and transimpedance of the amplifier channel are 652MHz, 99dBΩ. Under the simulation condition of TT corner and 27℃, the propagation delay of the discriminator is 2.15ns and the propagation delay dispersion is 223ps. The power consumption during continuous measurement is 810mW, and the operating temperature range of the device is -10~60℃.
A 3D laser imaging test facility was developed and established using a module design approach. The test facility
provides a complete, controllable and repeatable experiment environment, and supports research and simulation of 3Dimaging
LiDAR system. The test facility consists of five major parts: an open 3D-imaging LiDAR, a target simulator, a
far-field emulation, a background light environment simulation system, and a large FOV stereo vision system. The test
facility has been set three working modes: unit module analysis mode, accuracy and imaging mechanism of LiDAR
system mode, moving target detecting and environmental modeling mode. The open test facility continually evolves to
meet the expanding role of 3D laser imaging applications.
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