利用延时法进行高精度脉冲激光测距

High-precision pulsed laser measuring distance by time delay method

由于激光测距的精度取决于时间测量精度,本文提出了一种提高时间测量精度的方法。该方法在现场可编程门阵列(FPGA)的控制下,将电信号通过延时电路送入到D触发器的输入端CLK;激光器发出的光到目标,经过目标反射后返回进入光电转换器转变为电信号送入到D触发器的输入端D。通过调整延时芯片和机械位移产生的电信号的延时时间,使D触发器输入端的信号同时到达,从而利用延时时间来确定光到达目标所需的时间。用FPGA对100MHz恒温晶振器的脉冲计数,经MC100EP195芯片延时,再通过精密机械定位的方法将时间测量精度提高到0.3ps数量级。实验结果表明:使用该方法,激光测距的误差在1km内能保证在0.1mm数量级,可满足高精度测距的要求。

Since the accuracy of laser ranging depends on the accuracy of time measurement,this paper introduces a method to improve the accuracy of time measurement.Under the control of a Field Programming Gate Array（FPGA）,the electric signal is transported into the CLK port of a D flip-flop through a delay circuit,the laser sends a laser beam to the target and the target reflects the laser beam back to the photoelectric converter.Then,the laser beam is changed to an electric signal and transported to the D port of D flip-flop.By adjusting the delay time of electric signal produced by a delay chip and mechanical displacement,the laser makes the signal of input ports of D flip-flop arrive at the target at the same time.Therefore,the delay time can be utilized to determine the time of laser arriving the target.Furthermore,the FPGA is used to count the pulse of a constant temperature crystal oscillator with 100 MHz,the MC100EP195 is used to delay and then the accuracy of time measurement is improved to 0.3 ps by the mechanical location method.The experimental results show that the measurement accuracy of the target in 1 km has reached to 0.1 mm,which means that the method can satisfy the requirements of high-precision ranging.