Repetitively pulsed, 70-J photolytic iodine laser with excellentoptical and long/reliable operation

The performance of a repetitively pulsed, 70 joule, closed cycle 1.3 μM photolytic atomic iodine laser with excellent beam quality (BQ=1.15) is presented. This BQ was exhibited in the fundamental mode from a M=3.1 confocal unstable resonator at a 0.5 Hz repetition rate. A closed cycle scrubber/laser fuel system consisting of a condensative-evaporative section, two Cu wool I₂ reactor regions, and an internal turbo-blower enabled the laser to operate very reliably with low maintenance. The fuel system provided C₃F ₇I gas at 10-60 torr absent of the photolytic quenching by-product I₂. Using a turbo-molecular blower longitudinal flow velocities greater than 10 m/s were achieved through the 150 cm long by 7.5×7.5 cm² cross sectional photolytic iodine gain region. In addition to the high laser output and excellent BQ, the resulting 8-12 μs laser pulse had a coherence length greater than 45 meters and polarization extinction ratio better than 100:1. Projections from this pulsed photolytic atomic iodine laser technology to larger energies, higher repetition rates, and variable pulse widths are discussed