United States of America As Represented by the Secretary of the Air Force

David P Dimiduk

LaVerne A Schlie

Bruce S Masson

A compact, high-repetitively(rep)-rate photolytic atomic iodine laser (PIL) using blowdown flow and cryogenic pumping increases the rep rate from 0.5 Hz to at least 10 Hz. The average power of the pulsed laser increases from 35 to 700 Watts output. The present invention maintains the demonstrated beam quality of better than 1.5 x diffraction limited, a coherence length of greater than 45 meters, to J/pulse output energy; polarization extinction ratio greater than 100:1; pulse length of 7-12 sec; and jitter less than 1 radian. The laser power and beam quality in this type of device is relatively insensitive to the actual fuel pressure and temperature in the laser cavity at the time of the pulse. The cavity pressure is allowed to vary between plus or minus thirty percent of the optimal value of the cavity height-pressure product of 300 torr-cm during the run period of nominally twenty seconds. Flow is established by boiling liquid C.sub.3 F.sub.7 I at a temperature of 10.degree. C. A high-thermal-conductivity aluminum foam provides thermal mass for boiling the liquid uniformly for the designed duration burst operation. Flow through the gain cell is transverse to the lasing optical axis, in contrast with the longitudinal flow in the previous 70 J device. The gas flow through the cavity is initiated and turned on and off with a large diameter fast valve. An adjustable flow straightener ahead of the gain region provides pressure drop to insure uniform flow over the entire cross sectional area.

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Albuquerque, NM, United States of America

David P Dimiduk