基于激光调频连续波(FMCW)测距的原理搭建了双光路FMCW测距系统,用正弦调频替代了传统的线性调频,提高了扫频速率。研究了正弦调频下的FMCW测距原理,推导了正弦扫描的重采样公式,提出了信号拼接的方法来增大扫描带宽,并通过正交调制的方法消除拼接误差。实验结果表明,使用正交调制的方法拼接等光频重采样校正的信号后,频谱分辨力可达127 μm,接近理论分辨力。在3.3~4 m的范围内,所提方法的结果与参考干涉仪的误差不超过203 μm,标准差小于194 μm。

Based on the principle of distance measurement of laser frequency modulated continuous wave (FMCW), a distance measurement system of dual optical path FMCW is set up, which replaces the traditional linear frequency modulation with sinusoid frequency modulation so as to improve the sweep frequency. The principle of distance measurement of FMCW under sinusoid frequency modulation is also studied, the resampling formulas of sine sweep is derived, and the signal synthesis method to increase the sweep bandwidth and the quadrature modulation method to eliminate the stitching error are put forward. The experimental result shows that after the quadrature modulation method is used to splice the equal-light frequency resampling correction signal, the frequency resolution reaches to 127 μm, very close to the theoretical resolution. It is no more than 203 μm of the error and less than 194 μm of the standard deviation compared with the reference interferometer within the range between 3.3 and 4 meters.