基于双频测尺的大尺寸空间激光测距方法研究

Research on Phase-difference Measuring Methods in Laser Range Based on Two Measurement Rulersat Large Scale Space

相位式激光测距采用连续波测相,为实现高精度鉴相,单频测尺的调制频率相应地提高,导致测距系统的空间尺度变小。为实现大尺寸空间的激光测距,文中在FPGA上设计实现双频测尺的鉴相系统,两测尺均采用全相位频域数字鉴相法。鉴相系统在不同信噪比的信号下的实验表明,通过控制两测尺之间的频差,有效降低了测尺间干扰;低频测尺测距范围75 m,高频测尺测距精度可达0.4 mm,系统整体鉴相精度0.08°,测量速度每秒50万次,满足了大尺度空间中相位式激光测距的应用需求。

Continuous wave phase measurement was applied in phase difference laser range finder. In order to achieve high accuracy,the relevant modulation frequency is high,so that this single measurement ruler had a small measuring range. In order to implemented laser range finder at the large scale space measurement,the FPGA implementation scheme of tw o measurement rulers was designed to determine the phase-difference based on all-phase spectrum analysis. Experiments on phase system under signal with different signal-to-noise ratio show that the interference betw een tw o measurement rulers was negligible when the difference of the tw o frequencies was suitable.The measurement range of 75 meters was achieved by the low frequency ruler,the accuracy of all-phase Fast Fourier Transform（ FFT）can reach 0. 08°（ i. e.,0. 4 mm at a modulation frequency of 80 MHz） by the high frequency ruler. The measurement frequency of the system was 500 kHz. The performance of the system meets the requirements of new applications in the phase difference laser range finder.