激光位置探测器的角位移测量精度分析

Angular Displacement Precision of Laser Spot Position Sensors

作为激光光斑位置探测器,象限探测器和位敏探测器被广泛应用于激光光斑跟踪、监控、位置检测和定位等领域。对这两种探测器的角位置测量精度进行了探讨,分析了影响精度的主要噪声源,推导出两者的角位移精度表达式,并通过计算进行了模拟。结果显示,两者的测量精度决定于信号的信噪比,且随作用距离的增加而降低;象限探测器的角位移测量精度明显高于位敏探测器。在忽略背景光噪声的情况下,象限探测器的精度约为位敏探测器的40倍。

Quadrant photodiode （QPD） and position sensitive device （PSD） are widely used in comraercial and industrial applications where high-speed position sensing, laser spot tracking and monitoring are needed. The incremental sensitivity of the PSD and QPD receivers depend on the lateral transfer characteristics and signal current distribution, on noises originating from the detectors, preamplifier and background, and on the noise correlation between signal channels. The factors above are analyzed and the dominating noise sources are evaluated in this paper. Finally the precisions of the PSD and QPD receivers are compared under conditions of low and high background illumination. The results show that without background illu-mination a QPD receiver provides roughly 40 times better precision and the precision of a QPD receiver, ahhough being limited by background noise, is still very much better than that of a PSD.