Thermal-defocusing/scattering optical limiter

Operation of an f/5 thermal-defocusing/scattering optical limiter is described. Thermal-defocusing limiting of 6-ns-duration, 532-nm laser pulses occurs by use of the broadband-absorbing dye Nigrosin dissolved in carbon disulfide. Additional limiting due to thermally induced scattering occurs at high incident fluences (above a threshold fluence) when either surface-roughened BASF-1 glass windows are in contact with the dye solution or microscopic glass fibers are added to the liquid cell. Limiter figures of merit are improved by factors of 2 and 4, respectively, over that of a purely thermal-defocusing limiter.