The Use of Dynamic Filtering as a Means of Laser Eye Protection

With the growing uses and new developments in the field of laser radiation it has become increasingly vital to perfect an eye protection device for the safety of industrial workers and combat troops. An ideal dynamic filter has high visible transmittance at ordinary light levels and high optical density at increased laser powers. This is accomplished with a three level system. Absorption of laser radiation would populate an excited singlet state. If the decay to the ground state is slow and a higher excited singlet, of the proper energy separation, exists with a sufficiently large extinction coefficient, then dynamic filtering will take place. Heptaphene, phthalocyanine aluminum chloride, Sudanblack B, and Indanthrone have shown an increase in optical density over that of the ground state when subjected to a Q-switched laser.