Mid and Far Infrared Vidicon Investigations of Thermal Lensing, Interference, and Thermal Radiation from Laser Windows,
AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MASS
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The authors report results of investigations of lensing and interference effects on the transmission of 10.6 micrometer CW laser beams through material windows. The evolution of the transmitted beam profile is recorded employing a real-time IR Vidicon detection system observations are carried out on a variety of windows, including Irtran-4, Si, KCl, BaF2 and CsBr. The phenomena observed include lensing, slewing and interference, and combinations thereof. The majority of the observations may be interpreted in terms of existing theoretical models the slewing effect, however, remains unaccounted for as yet. Also described is a novel technique in which the thermal profile in the window is recorded simultaneously with the transmitted pattern, by employing a GE Vidicon sensitive in the 2.3-4.5 micrometer range to spatially image radiation emitted by the window. The results suggest that scattering and absorption near the periphery of circular samples may be an important mechanism in determining the heat distribution in the window.
- Lasers and Masers