REPETITIVELY PULSED, CLOSED CYCLE, PHOTOLYTIC ATOMIC IODINE LASER

摘要

A repetitively pulsed, high energy, closed cycle photolytic atomic iodine lasers operates at 1.315 microns. Using an iodine (I2) removal system for the photolyzed C3F7I laser fuel, more than 70 joules/pulse is output in the fundamental mode from an M = 3 confocal unstable resonator at a 0.5 Hz repetition rate. The closed cycle iodine (I2) removal system consisted of a condensative-evaporative section, two Cu mesh I2 sections, and an internal turbo-molecular blower. This closed cycle system uses C3F7I gas at 10-60 torr absent of I2. The turbo-molecular blower is able to push high molecular weight gases at high velocities. The turbo-molecular blower is able to produce longitudinal flow velocities greater than 10 m/s through the 150 cm long by 7.5 x 7.5 cm2 cross-sectional photolytic iodine gain region. In addition to the high energy output, the resulting 7-12 .mu.sec laser beam has a beam quality less than 1.5 times diffraction limited with a coherence length greater than 45 meters, and a polarization extinction ratio better than 100:1. The laser beam was observed to jitter less than 1 microradian. In order to produce high energies, higher repetition rates, and variable pulse widths, a transverse flow gain cell is employed along with electro-optical switches for the flashlamps.