Photon counting pseudorandom noise code laser altimeters
Photon counting pseudorandom noise code laser altimeters
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DOI：
10.1117/12.735453
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发表时间：
2007-09
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影响因子：
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通讯作者：
Xiaoli Sun;J. Abshire;M. Krainak;William B. Hasselbrack
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文献类型：
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作者：
Xiaoli Sun;J. Abshire;M. Krainak;William B. Hasselbrack
研究了光子计数伪随机噪声(PN)码激光测距系统在1064 nm和1570 nm两种波长下的性能。伪码调制是一种广泛应用于电信和射频测距应用的二进制信号。当用于激光雷达时，伪码调制允许发射机以峰值功率工作，仅等于与光纤通信技术兼容的平均功率的两倍。我们的光子计数接收器方法将接收到的光子流累积成直方图，然后将直方图与原始PN码序列互相关。飞行时间由相关函数中峰值的位置给出。对于激光光束足迹内的多个目标，每个目标在对应于目标范围的延迟处产生相关函数中的峰值。我们的测高方法也使用比PN码比特周期短得多的接收器距离仓。这允许以比PN码位周期更高的时间分辨率来计算相关性，并且显著提高了时间和距离分辨率。我们使用面包板接收器进行的实验室测量显示，使用InGaAsP混合光电倍增管探测器时，在0.5毫秒的积分时间内，在1064 nm处平均接收光功率为50FW时，探测概率大于90%。当使用250PSEC测距箱和大约100 kHz的探测信号光子速率时，我们还获得了小于5 cm的RMS测距精度。
We have characterized the performance of photon counting pseudorandom noise (PN) code laser ranging system at both 1064 and 1570 nm. The PN code modulation is a binary signal which is widely used in telecommunications and RF ranging applications. When used in lidar PN code modulation allows the transmitter to operate with a peak power, equal to only twice the average power which is compatible with the optical fiber communication technology. Our photon counting receiver approach accumulates the received photon stream into a histogram, then cross correlates the histogram with the original PN code sequence. The time of flight is given by the location of the peak in the correlation function. For multiple targets within the laser beam footprint, each target produce a peak in the correlation function at the delay corresponding to the target range. Our approach for altimetry also uses receiver range bin much shorter than the PN code bit period. This permits the correlation to be calculated with higher time resolution than the PN code bit period and substantially improves the time and range resolution. Our laboratory measurements with a breadboard receiver shows a greater than 90% probability of detection in a 0.5 msec integration time with 50 fW average received optical power at 1064 nm when using an InGaAsP hybrid photomultiplier tube detector. We have also achieved a less than 5cm rms ranging precision, when using a 250 psec range bin and at about 100 KHz detected signal photon rate.