TERRESTRIAL SOLAR-PUMPED IODINE GAS-LASER WITH MINIMUM THRESHOLD CONCENTRATION REQUIREMENTS

A t-C4F9I iodine gas laser pumped by concentrated uv terrestrial solar radiation was designed and built. The laser consists of an optical re sonator cavity, a blowdown lasant gas now system, and a parabolic trou gh reflector. The optical resonator design was based on a mathematical model that used iodine gas kinetic rate equations to predict threshol d pumping power, available pumping power, and laser output power for v arious dimensions. An optimum design for this demonstration project wa s selected to minimize lasing threshold solar concentration to 40 suns , and retain a 15-min run time with our limited lasant supply, Output power was not optimized, and is predicted to be low (20 mW). An estima te of local spectral uv terrestrial irradiation was developed from ban d and total irradiation measurements. It was used to estimate solar co ncentration required to initiate lasing and laser output power. The la ser, gas flow system, and parabolic trough collector were built and ev aluated. Irradiation at the parabolic trough's focus (where the laser tube was placed) was measured for directional and total irradiation. T hese measurements showed an average solar concentration of 15-20 suns below threshold. The study establishes the feasibility of terrestrial solar-pumped iodine lasers with low threshold, and simple, stable, and controllable lasant flow systems.