Maurice W Windsor; W R Dawson; R S Moore; D Weber; TRW SYSTEMS REDONDO BEACH CALIF CHEMICAL SCIENCES Dept.
A normally transparent screen is needed that can be darkened quickly enough to protect the eyes of combat pilots who may be exposed to flashes from nuclear explosions. Strong absorption of visible light from the lowest triplet level of selected aromatic compounds is a promising basis for development of the required screen for prevention of flashblindness. This triplet absorption, which may be induced by absorption of ultraviolet light from microsecond flash lamps, decays in a few seconds so that transparency is spontaneously restored. A method of measuring extinction coefficients of triplet absorption and quantum yields of triplet formation has been developed. Combinations of aromatic compounds giving strong triplet absorption of visible light over the visible spectrum with minimized excitation energy are selected on the basis of these results. Two promising compounds have been synthesized. New plastics having greater solubility for large aromatic molecules than polymethylmethacrylate have been found. A method of making large sheets of polymethymethacrylate with exceptionally high transparency to ultraviolet is described. Deleterious effects of exposure of plastics, with and without aromatic solutes, to oxygen and sunlight have been studied. It was shown that diffusion of oxygen into the plastic sheets may be greatly reduced by a polyvinyl-alcohol coating. The application of these experimental results to the design of a protection device against flashblindness is discussed. (Author).