APD阵列可提高光子探测效率, 然而在回波探测概率提高的同时提高噪声探测概率, 因此需合理选择阵列单元数以提高探测信噪比。根据回波和噪声在距离门内的分布情况, 结合光子探测概率, 建立了盖革模式下APD阵列探测信噪比随阵列单元数的变化模型。讨论了回波光子数、背景噪声强度、回波在门控内位置、占空比等因素对探测信噪比的影响。分析结果表明, 提高回波光子数、探测器占空比、轨道预报精度有助于增加APD阵列的探测信噪比; 4元APD阵列适用于回波光子数小于0.1、门控内噪声光子数小于1的观测情况, 而回波和噪声强度较强时, 25元APD阵列能够取得相对较优的探测信噪比。建立的APD阵列探测信噪比模型有助于快速选择APD阵列单元数以达到较高探测信噪比。

APD arrays provide an efficient method for photon detection probability improvement. However, the noise detection probability increases as well as the echo detection probability. Properly choosing the unit number of APD arrays means a lot for signal-to-noise ratio (SNR) improvement. In this article, according to the photon detection probability in the Geiger-mode, the SNR model with the unit number N was established based on the distribution of echoes and noise within the range gate. Effects of number of echoes, noise rate, location of echoes and fill factor were discussed. Analytical results show that larger number of echoes, higher fill factor and more precise orbit prediction help increase the SNR with APD arrays. 4-unit APD arrays are enough for laser ranging with echo number smaller than 0.1 and noise number within the range gate smaller than 1, while when there are large number of echoes and noise, 25-unit APD arrays will achieve a better SNR. The established SNR model for APD arrays will help for proper unit number selection to achieve the best SNR.