相位式双频激光拍波测距方法研究

With the fast development of technology, high resolution, fast and dynamic distance measurements are needed in more and more fields. The precision of traditional phase-shift range finder is limited by its measurement rate, and the dynamic range is constrained by fuzzy distance. The modulation depth of laser diode decreases with increased modulation frequency, which is essential to obtain high precision by the sinusoidal modulation. This research is focusing on some key technologies of phase-shift laser range finding utilizing the beat-wave of dual-frequency laser and exploring a new method on the base of principle of laser range finding. A dual-frequency He-Ne laser with adjustable frequency difference is going to be applied as the laser source of measurement, and the non-fuzzy measurement technology is going to be developed by multi-frequency difference. A model of error transferring is about to be built in order to analyze the factors influence the precision of phase-shift laser range finder and to minimize the disturbance in procedure of phase metering. In order to reduce the phase discrimination error in phase-shift laser range finder, the Hilbert transform is about to be introduced during the processes before spectrum analysis, it helps to realize unbiased phase difference measurement. It will conduce to lending a new technique to solve the key problems in high precision and wide dynamic phase-shift laser range finder.

随着科技的发展，工业生产领域需要更高精度，更快速响应的测距方法。传统的相位式激光测距技术存在着测量精度与测量速率间的矛盾，模糊距离，半导体激光器对高频调制信噪比的制约等问题，而双频激光技术的发展为解决这些技术瓶颈提供了新途径。本研究结合相位式激光测距的原理，探索采用差频可调谐的双频He-Ne激光器产生拍波信号作为光源，实现多频测尺无模糊相位式激光测距的新方法。通过分析影响测量精度的各种因素，构建误差传递模型，研究抑制干扰的相位检测技术，并基于全相位谱分析的鉴相方法，引入希尔伯特变换，消除数据处理过程中的鉴相偏差。为解决高精度、大动态范围的相位式激光测距技术发展中的若干关键问题提供新思路。

更高精度的激光测距方法一直是工业生产领域的重要研究方向之一，利用拍波调制光源能获得较好的信噪比和调制深度等特点，本课题在双频激光拍波产生机理的基础上开展了相位式测距系统研究。探讨了多种能应用于双频激光拍波测距中的鉴相方法，通过合理的参数配置获得了较高的测距精度。在实践中，采用了氦氖稳频激光器双纵模效应形成的偏振光合成了激光差频拍波，作为测距光源具有了良好的测量特性。通过仿真分析了影响测量精度的各种因素，针对主要误差来源，设计了高带宽、高增益的光电检测电路提取参考端与测量端的相位差，研究了抑制干扰的相位检测方法。通过合理地设置鉴相算法参数，发现欠采样谱分析和全相位FFT谱分析方法在不同场合均能达到较高的鉴相精度。课题在研究中搭建了双频激光拍波相位式测距系统，设计了多组测距实验，发现采用双频激光差频拍波作为光源的相位式测距系统在多种情况下均能获得较高的测距精度。