Repetitively pulsed, closed cycle, photolytic atomic iodine laser

Abstract

A repetitively pulsed, high energy, closed cycle photolytic atomic iodine lasers operates at 1.315 microns. Using an iodine (I.sub.2) removal system for the photolyzed C.sub.3 F.sub.7 I laser fuel, more than 70 joules/pulse is output in the fundamental mode from a M=3 confocal unstable resonator at a 0.5 Hz repetition rate. The closed cycle iodine (I.sub.2) removal system consisted of a condensative-evaporative section, two Cu mesh I.sub.2 sections, and an internal turbo-molecular blower. This closed cycle system uses C.sub.3 F.sub.7 I gas at 10-60 torr absent of I.sub.2. 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.times.7.5 cm.sup.2 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.