Anti-aliasing techniques in photon-counting depth imaging using GHz clock rates
Anti-aliasing techniques in photon-counting depth imaging using GHz clock rates
复制标题
使用 GHz 时钟速率的光子计数深度成像中的抗锯齿技术
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
G. Buller
中科院分区：
文献类型：
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作者：
N. Krichel;A. Mccarthy;R. Collins;G. Buller
单光子检测技术与低激光照明功能结合使用，可以在非合作目标表面上获得安全的飞行时间范围信息。我们先前提出了一个光子计数深度成像系统，旨在通过在感兴趣的场角上转向单个扫描像素，旨在快速获取三维目标模型。为了最大程度地减少获得足够的光子统计量以准确距离分辨率所需的每个像素住宅时间，应用了以多MHz重复率的定期照明。现代时间相关的单光子计数（TCSPC）硬件允许使用子-MM精度进行深度测量。仅在足够短的距离上可以使用快速周期信号解析绝对目标范围：如果将对象的往返时间延长了两个触发脉冲之间的时间段，则无法将返回信号分配给明确的范围值。尽管仍然可能基于相对结果构建精确的深度图像，但出现了大型或未知像素的逐像素分离的问题，或者在可能的场景距离范围很大的应用中出现。我们引入了一种技术，以避免以高平均脉搏率的飞行时间深度成像系统的范围歧义效应。长伪随机bitstream用于触发照明激光。循环，快速支持的分析算法用于搜索返回光子事件中的模式。我们以高达2 GHz的基本时钟速率证明了这种方法，图案长度不同，可以实现几公里的明确距离。扫描在长时间的距离距离和具有较大像素到像素范围差异的场景差异。进行数值模拟以研究该技术的相对优点。
Single-photon detection technologies in conjunction with low laser illumination powers allow for the eye-safe acquisition of time-of-flight range information on non-cooperative target surfaces. We previously presented a photon-counting depth imaging system designed for the rapid acquisition of three-dimensional target models by steering a single scanning pixel across the field angle of interest. To minimise the per-pixel dwelling times required to obtain sufficient photon statistics for accurate distance resolution, periodic illumination at multi- MHz repetition rates was applied. Modern time-correlated single-photon counting (TCSPC) hardware allowed for depth measurements with sub-mm precision. Resolving the absolute target range with a fast periodic signal is only possible at sufficiently short distances: if the round-trip time towards an object is extended beyond the timespan between two trigger pulses, the return signal cannot be assigned to an unambiguous range value. Whereas constructing a precise depth image based on relative results may still be possible, problems emerge for large or unknown pixel-by-pixel separations or in applications with a wide range of possible scene distances. We introduce a technique to avoid range ambiguity effects in time-of-flight depth imaging systems at high average pulse rates. A long pseudo-random bitstream is used to trigger the illuminating laser. A cyclic, fast-Fourier supported analysis algorithm is used to search for the pattern within return photon events. We demonstrate this approach at base clock rates of up to 2 GHz with varying pattern lengths, allowing for unambiguous distances of several kilometers. Scans at long stand-off distances and of scenes with large pixel-to-pixel range differences are presented. Numerical simulations are performed to investigate the relative merits of the technique.