Plasma shielding by Q-switched and mode-locked Nd-YAG lasers.

ABSTRACT

Q-switched and mode-locked Nd-YAG lasers depend on beam divergence and plasma formation to reduce energy transmission below the retinal damage threshold. In a model system of physiologic saline, we investigated plasma "shielding" and found that plasma formation markedly reduces further energy transmission along the beam path once plasma formation occurs. The protective effect of plasma shielding appears similar for a Q-switched pulse and a train of mode-locked pulses in a physiologic saline medium.