Precision-Improved Pulsed Laser Ranging by Multi Delayed Echo Signals Triggering

We propose a pulsed laser ranging method based on a multiecho delay trigger, which improves the precision of pulsed laser ranging. A signal delay unit is used to accurately delay the pulse-echo signal. In a fixed time window, the echo delay pulse triggers the laser transmitter to generate pulsed laser light; meanwhile, the counter records several echo pulses received, and then, the actual distance can be calculated. In terms of improving the ranging precision, this method overcomes the essential of higher time resolution time-to-digital converter (TDC) chip in traditional time-of-flight (TOF) pulsed laser ranging. The method can be realized by using a field-programmable logic gate array (FPGA) chip, a delay unit, and a set of laser transmitters and receivers, which makes the system structure simple and low cost. Experimental results show that this method can achieve more accurate distance measurement and significantly reduced error, to the best of our knowledge, which improves the pulsed laser ranging from centimeter- to millimeter-order precisions. We believe that this method has a promising application prospect in the field of high-precision pulsed laser ranging of fixed targets.