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利用相干激光雷达探测目标微动特性技术是一种以单频激光为光源,用外差探测的方式实现对低速、低频多个运动物体进行微多普勒信息提取和识别的技术。以波长为1.064μm的窄线宽单块激光器为光源,发射激光经过模拟长距离传输的4 km的光纤延迟,照射到以扬声器的发声单元和电动平移台为目标的微动物体上,目标反射的激光会聚进入单模光纤,参考光与信号光通过3 dB光纤合束器线性耦合进入同一根光纤,并在探测器表面进行相干。用于接收相干信号的探测器的接入方式为光纤输入,带宽为3.5 GHz。利用时间-频率域联合描述的方法对数/模(A/D)采样后的数据进行分析。在4 km光纤延迟时,本系统最低探测速度为0.5 mm/s,速度分辨率达到毫米每秒量级,频率分辨率达到千赫兹量级。利用微多普勒信息探测技术,实现了探测物体表面的微动状态信息和识别运动状态的目的。
The technique of detecting the target fretting characteristics by using coherent laser radar is a technique of using single-frequency laser as light source and using heterodyne detection to realize the micro-Doppler information extraction and recognition of a plurality of moving objects at low speed and low frequency. A narrow linewidth monolithic laser with a wavelength of 1.064μm was used as the light source. The laser beam was transmitted through a 4 km optical fiber cable simulating a long-distance transmission and impinged on a micro-object aiming at the speaker’s vocalization unit and motor translation stage. The target reflection Of the laser light converges into a single-mode fiber. The reference light and the signal light are linearly coupled through a 3 dB fiber-optic combiner into the same fiber and coherent on the detector surface. The probe used to receive the coherent signal is connected to the fiber input at a bandwidth of 3.5 GHz. The data after the sampling of A / D is analyzed using the method described in time-frequency domain combination. At 4 km fiber delay, the minimum detection speed of this system is 0.5 mm / s, the speed resolution reaches millimeter per second, and the frequency resolution reaches the order of kilohertz. The use of micro-Doppler information detection technology to achieve the purpose of detecting the micro-state information on the surface of the object and identifying the state of motion.