Second generation airborne 3D imaging lidars based on photon counting
Second generation airborne 3D imaging lidars based on photon counting
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DOI：
10.1117/12.732086
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发表时间：
2007-09
影响因子：
5.6
通讯作者：
J. Degnan;D. N. Wells;R. Machan;E. Leventhal
中科院分区：
文献类型：
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作者：
J. Degnan;D. N. Wells;R. Machan;E. Leventhal
第一个成功的光子计数机载激光高度计于2001年在NASA的仪器孵化器计划（IIP）下进行了演示。这个“微型高度计”飞行高度高达22000英尺（6.7公里），在白天使用单光子返回，成功记录了下面地形的高分辨率图像，包括土壤、低洼植被、树冠、水面、人造结构、海浪和移动车辆。激光雷达的工作波长为532纳米，接近太阳辐照曲线的峰值，它还能够透过树木和厚厚的大气雾霾看到下面的地形，并在大西洋和弗吉尼亚海岸的阿萨旺湾进行几米深的浅水测深。西格玛空间公司最近开发了适用于小型飞机或微型无人机的第二代系统。频率加倍的Nd:YAG微芯片激光器以高达22千赫的射速产生几微焦耳、亚纳秒的脉冲。衍射光学元件（DOE）将发射光束分解成10x10的准均匀光斑阵列，这些光斑由接收光学元件成像到高效率的10x10 GaAsP分段阳极微通道板光电倍增管的单个阳极上。每个阳极输入到100通道的一个通道，多停止定时器被证明具有100皮秒定时（1.5厘米范围）分辨率和事件恢复时间小于2秒。双楔形光学扫描仪的模式和频率与激光射速同步，可在单次飞越中提供对地面场景的连续覆盖。
The first successful photon-counting airborne laser altimeter was demonstrated in 2001 under NASA's Instrument Incubator Program (IIP). This "micro-altimeter" flew at altitudes up to 22,000 ft (6.7 km) and, using single photon returns in daylight, successfully recorded high resolution images of the underlying topography including soil, low-lying vegetation, tree canopies, water surfaces, man-made structures, ocean waves, and moving vehicles. The lidar, which operated at a wavelength of 532 nm near the peak of the solar irradiance curve, was also able to see the underlying terrain through trees and thick atmospheric haze and performed shallow water bathymetry to depths of a few meters over the Atlantic Ocean and Assawoman Bay off the Virginia coast. Sigma Space Corporation has recently developed second generation systems suitable for use in a small aircraft or mini UAV. A frequency-doubled Nd:YAG microchip laser generates few microjoule, subnanosecond pulses at fire rates up to 22 kHz. A Diffractive Optical Element (DOE) breaks the transmit beam into a 10x10 array of quasi-uniform spots which are imaged by the receive optics onto individual anodes of a high efficiency 10x10 GaAsP segmented anode microchannel plate photomultiplier. Each anode is input to one channel of a 100 channel, multistop timer demonstrated to have a 100 picosecond timing (1.5 cm range) resolution and an event recovery time less than 2 nsec. The pattern and frequency of a dual wedge optical scanner, synchronized to the laser fire rate, are tailored to provide contiguous coverage of a ground scene in a single overflight.