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.
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.