Attenuation of High Intensity Reradiated Light by Photochromic Glass.

摘要

One possible threat mechanism by which High Energy Laser Weapons may exploit the vulnerability of U.S. Army systems is through the production of large fluences of reradiated visible light when glass surfaces such as windscreens, vision blocks or lenses are struck by pulsed or cw laser radiation. At 10.6 meter laser wave lengths silicate glasses have very shallow absorption depths and, hence, heat to incandescence rapidly. Such blackbody surfaces at temperatures of 3000 (C+) will reradiate strongly in the visible region of the spectrum. In addition, if pulsed laser conditions are such that air plasmas are formed on the target, blackbody temperatures of 17,000 C may be obtained. This paper does not attempt to address flashblindness conditions; rather it focuses on the enhanced attenuation of the visible light in the optical materials behind the target surface. This paper reports a set of experiments to test the concept of the photochromic glass response as countermeasure against the visible reradiation obtained when transparent materials are irradiated by high energy lasers. In all of the experiments, a fused silica face plate (chose because of ultraviolet (uv) transparency) was the target and a laminate of four layers of the photochromic glass was placed behind the fused silica. Attenuation of visible light traversing the photochromic glass was measured.