宽调谐激光雷达亚毫米级距离分辨的实现方法

Realization method of range resolution of sub-millimeter in widely tunable laser radar

分析了单相干通道的宽调谐激光雷达虽具有超大带宽但不能实现符合理论值的距离高分辨率的原因,以及导致非线性调频相位误差的因素。构建了解决这一难题的双相干通道宽调谐激光雷达系统,啁啾带宽在THz量级,引入了具有固定延时的参考通道,采用了有效的信号处理方法,从参考通道中提取出相位误差,再利用此相位误差数据自适应地补偿掉目标通道中的相位误差。实验结果证明,该系统将距离分辨率由米级提高到了200μm左右,接近理论值120μm,实现了低至100 pW的最小可利用回波功率。且即使目标通道和参考通道的延时不相等时,该方法仍有效。

The reason that widely tunable laser radar with single coherent channel could not achieve fine range resolution agreed with nominal value despite of its huge bandwidth and the factor that leads to nonlinear frequency modulation phase error were analyzed theoretically. Widely tunable laser radar system with two coherent channels was set up to resolve this problem. The chirp bandwidth of system was THz magnitude. Reference channel with fixed delay was added in this dedicated system, and the active signal processing method was utilized. After the phase error was extracted from reference channel, the phase error in target channel was computed and compensated for it adaptively. Results of experiment prove that, the range resolution of this kind of system is improved from about ＂m＂ magnitude to 200 μm which is approaching nominal value of 120 μm, and the weakest echo power for ranging reaches as low as 100 pW. This technique is shown to work even if the delays of target and reference channel are not equal.