Double-pulse laser experimental results of generating approximately 100 ns temporal delay between the pulses with
polarization beam combining by two sets of flashlamp pumped electrooptical Q-switched laser is reported for the first
time. The interval of co-aligned double-pulse laser can be turned freely from 0 to several hundred nanoseconds. The
maximal relative timing jitter of double-pulse laser is less than 5 ns. The laser beam control is another difficult issue in
developing double pulse laser. Two 1/4 λ waveplates are inserted in the double pulse laser, and the thermal induced
birefringence can be effectively compensated, and the Q-switched laser pulse energy can be increased by 26 percent. The
repetition rate of double-pulse laser is 40 Hz, and output energy per double-pulse is more than 400 mJ.
This paper is a review of progress of laser rangefinders with digital signal processing. Correlation selection can be used
with reduced signal-detection threshold for a determined distance. Time-of-flight method of measuring the range, by
using in the detector channel a reduced signal-detection threshold for fixing the time position, in combination with
correlation selection to distinguish the signal pulses on a background of an intense flux of noise spikes, are proposed for
the possibilities of improving the detection and accuracy characteristics of pulsed laser rangefinders.