Pulse code modulation of laser pulse tail

A system for pulse code modulating the tail portions of a train of pulsed laser beams to provide coded messages for information transfer, said system comprising:

• linearly polarized CO.sub.2 TEA laser activated by a trigger pulse generator to produce a train of output laser beam gain switched spikes with tail portions therefrom;
• telescoping optics for demagnifying the output laser beam;
• a beam splitter positioned at the output of said telescoping optics in optical alignment with said linearly polarized CO.sub.2 TEA laser and said telescoping optics, said beam splitter placed at the Brewster's angle to simultaneously reflect a portion of each output laser beam gain switched spike and tail portion while transmitting the remainder therethrough;
• an electrooptics Pockels Cell modulator means in optical alignment with said beam splitter to directly receive the laser beam gain switched spike and tail portions transmitted through said beam splitter;
• an electronic modulating circuit that receives the reflected portion of the output laser beam gain switched spike and tail portion onto a timing detector and after a time delay by said timing detector produces a train of coded pulse words of said tail portion that is applied to a high voltage pulse power supply wherein a train of high voltage pulses produced at the repetition rate of said train of coded pulse words are applied to said electrooptics Pockels Cell modulator means simultaneously with the arrival of the tail portion that is transmitted through the beam splitter wherein said train of high voltage pulses pulse code modulate said tail portion while selectively leaving said gain switched spike unmodulated said spike being used for ranging;
• and
• mirror and output optical means for transmitting the pulse code modulated data to a receiving station.