Shabnam Virji

Managing contamination-enhanced Laser Induced Damage (CLID)

Contamination-enhanced Laser Induced Damage (CLID) occurs when molecular or particulate contamination, present on or in the vicinity of an optical material, leads to accelerated laser power degradation and premature failure. The physical mechanisms that cause CLID are not sufficiently understood to predict the extent to which a contaminant will cause damage. Although standard computational methods can be used to predict the amount of contamination on an optic, the effects of those molecules or particles on laser performance has not been sufficiently quantified. This paper will describe an approach for managing CLID that relies on laboratory studies to understand the relationship between contaminant type or quantity and CLID thresholds. That insight can then be used to guide the definition of cleanliness requirements and the design of material screening tests. Initial efforts to study how mass transport, the movement of contaminants in and out of the laser beam, affects damage rates will be discussed as well.