Coherently pulsed laser source

摘要

An electronically controllable apparatus is described which modulates a continuous wave laser beam 22 so as to produce an output beam 42 consisting of coherent "pulses" that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices 24, 26 positioned so that the laser beam passes through them in sequence, and apparatus 32 or 34 for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device such as 24 generates sound waves containing a group of frequencies which result in spaced pulses. The spreading of a laser beam at 40 which emanates from the first acoustic device 24 is countered by the second acoustic device 26 to produce a collimated, coherently pulsed, laser beam 42.