Short pulse CO.sub.2 laser for ranging and target identification

A high precision pulsed CO.sub.2 laser rangefinder and target identifier device comprised of:

• a linearly polarized CO.sub.2 TEA laser triggered by firing logic to produce a train of laser beam gain switched spikes therefrom;
• an electrooptics Pockels Cell modulator in optical alignment with said train of laser beam gain switched spikes;
• means for activating said electrooptics Pockels Cell modulator in synchronism with each spike of said train of laser beam gain switched spikes to chop each of said spikes into a train of short evenly spaced linearly polarized laser pulses at the output therefrom;
• a circularly polarizing quarter wave plate in optical alignment with the output of said electrooptics Pockels Cell modulator for transforming said train of linearly polarized laser pulses into a train of circularly polarized laser pulses;
• common transmitter and receiver optics means for transmitting said train of circularly polarized laser pulses therefrom to a target scene and for receiving target return signals representing time broadened reflected signals that indicate the finite depth of the target and unique signature therethrough wherein said target return signals are converted back to linearly polarized light pulses by passing back through said quarter wave plate;
• a wide bandwidth receiving means that is range gated by said firing logic in synchronism with the triggering of said linearly polarized CO.sub.2 TEA laser, said receiving means receiving said target return signals resolving into range resolved cross sections to gather target signatures from different zones in the target plane and signal processing said target signatures;
• and
• a pattern recognition means having known target signatures stored therein for comparison with target signatures obtained from said target return signals to identify the target being pulsed by said train of circularly polarized laser pulses.