激光光斑质量对基于PSD的激光三角法长时间连续测量精度的影响

为了提高半导体激光器-位置敏感器件(LD-PSD)激光三角法测距、测厚系统的测量精度,对半导体激光器的光斑质量进行了研究。用不同功率的半导体激光器做静态测距实验,结果表明,在长时间连续测量中,激光光斑重心的漂移增大了系统的测量误差。光斑重心漂移主要是由光斑的高频噪声和光斑整体偏移造成的。针对这两方面因素设计了基于针孔滤波和棱镜分束的能够提高激光光斑质量的光学系统,并用CODEV软件进行了优化与仿真。将所设计的光学系统加入到测距仪中重新进行静态测距实验,结果表明,改善后的系统精确度由25μm提高到8μm,使得基于位置敏感器件的激光三角法测距、测厚系统在长时间连续工作时也能保持较高的测量精度。

Impact of Accuracy of Laser Spot Quality in Laser Triangulation Long-Term Continuous Measuring Based on PSD

The quality of laser spot is studied in order to improve the precision of distance and thickness measurement system based on laser diode-position sensitive device (LD-PSD) laser triangulation. Static distance measuring experiments with different powers of laser diodes are conducted. The experimental results show that drift of the center of spot intensity increases measurement errors of the system in long-term continual work. The drift is mainly caused by high-frequency noise and spot displacement. For these two factors, an optical system based on the pinhole filter and beam splitter with prisms to improve the quality of laser spot is proposed, which is optimized and simulated by CODEV. Static distance measuring experiments are conducted again after adding the designed optical system to the rangefinder. The new experimental results prove that the precision of the system is improved from 25 μm to 8 μm. The design improves the practicability of laser triangulation measurement system for distance and thickness measuring in long-term continual work based on PSD.