高分辨率调频连续波激光绝对测距研究

大空间精密测量在重大装备制造、空间科技、国防工业等方面发挥着重要作用,激光高精度绝对长度测量是大空间精密测量领域的重要研究课题.调频连续波激光测距是近年来激光绝对测距研究的热点,它克服了脉冲法测量分辨率低和相位法激光测距存在2π缠绕模糊度问题的缺点,有着测量精度高、量程大的优点.本文研究了调频连续波激光测距的原理,分析了影响其测距分辨率的主要原因,证明了利用等光频间隔采样来抑制激光调制非线性对测距结果影响的可行性.该方法可以提高测距分辨率,且系统构成简单、实用性强.搭建了光纤调频连续波激光测距系统,并加入了辅助干涉光路对测量信号进行等光频间隔采样.利用该系统进行了测距分辨率实验,实验结果表明,本系统测量分辨率可以达到50μm,测量范围达到了10m.

Absolute distance measurement by high resolution frequency modulated continuous wave laser

Large-scale high-accuracy measurement plays an important role in many applications, such as large-scale equipment manufacturing, space technology and national defense industry. High-accuracy absolute distance measurement by laser is an important research topic in the field of large-scale high-accuracy measurement. And frequency modulated continuous wave (FMCW) laser ranging is a hot point of research nowadays. Because this method is better than pulsed time-of-flight method in measurement resolution, and the problem of ambiguity in measurement, which is the main disadvantage of phase-related method, does not exist. In this paper, the principle of FMCW laser ranging and the main factors reducing the measurement resolution are analyzed. In order to improve the ranging resolution, the method using an auxiliary interferometer to sample the signal in equal intervals of optical frequency is employed. A dual interferometer FMCW laser ranging system is designed and the experiments are carried out. The experimental results show that the measurement resolution is 50 μm at a distance of 10 m.
Keywords： lasers frequency modulated absolute distance measurement interferometry