Attenuation of giant laser pulses by absorbing filters

Three types of absorbing filters were tested for suitability as reproducible attenuators for a Q-switched ruby laser beam. None of the filters tested were irreversibly damaged when irradiated with pulses having peak powers up to 40 MW (beam cross section ~10(-4) M(2)). However, Tiffen Photar neutral density filters and Corning filters showed reversible photobleaching (optical saturation) at large pulse energies, while Kodak Wratten neutral density filters did not saturate.