Precise ranging by emitting long laser pulses

A precise pulsed ranging method using long laser pulses was developed and tested experimentally. It is based on direct analog–digital sampling of both the reference and received pulses and their software processing by digital filtering, pulse shape retrieving, selections, pulse center calculation, and averaging. The method is effective for pulse widths longer than the sampling step, including the case when only one sample exceeds the threshold. A temporal accuracy on the order of 10 −2 of the sampling step and better can be realized in the optimal receiving regime. The method offers an approach for the creation of precise ranging instruments by using relatively long laser pulses. This was demonstrated on a 10.6 μm range-finding system emitting 500 ns laser pulses with time instability with respect to the triggering pulses. A ranging accuracy on the order of (3–5) cm was achieved using traditional 10 MHz/8 bit analog/digital converters. The method enlarges the set of prospective laser sources suitable for precise ranging and can be applied in different instruments based on the analog photon detection regime.