为了提高半导体激光器的光束稳定性, 减少长距离测量中激光光束的漂移, 本文设计了基于BP神经网络结合PID控制(BPNN-PID)的双反射镜激光器光束漂移自动补偿系统。在该系统中, 将两个四象限光电探测器分别置于测量近端和测量远端, 作为激光光束漂移的测量单元; 用两个带有压电陶瓷致动器(PZT)的二维角度调整架作为激光光束方向的调整单元。建立了激光光束漂移量与调整单元角度变化的模型, 并根据测量单元的输出, 通过BPNN-PID方法反馈控制调整单元的角度, 从而自动补偿激光光束漂移。实验结果表明: 使用该激光器光束漂移补偿方法, 在15 min时间内, 用于测量直线度误差和角度误差的激光测量系统的稳定性在测量距离1 m处, 分别从未控制时的±9 μm和±5″提高到了±3 μm和±1.5″。

To improve the stability of LDs and reduce the laser beam drift in long-distance measurement, a BPNN-PID-based dual-mirror laser-beam drift compensation method was proposed. Two four-quadrant photodetectors, which were placed at the near and far ends of the measurement position, were employed to measure the laser beam drifts. Two 2D precision-angle mirror mounts integrated with two piezoelectric actuators were used to adjust the propagation direction of the laser beam. A model relating the laser beam drift and the angular variation of the angle mirror mounts was established. The angular variation was then fed back with the proposed BPNN-PID method based on the output of the laser beam drift detector, from which the laser beam drift can be automatically compensated. It was verified that the signal stabilities of a laser measurement system that was used for measuring the straightness and angular errors of linear stages improved from ±9 μm and ±5″ without laser-beam drift compensation to ±3 μm and ±1.5″ with laser-beam drift compensation over 15 minutes.