Low absorption optical coating apparatus and related methods using thf4/baf2 combination

Abstract

A very low energy-absorption coating and related methods for use with high power CO2 lasers includes at least a thin layer of ThF4 (16) used as a water/moisture barrier, in combination with BaF2 (14), for various optical elements. When used in connection with a ZnSe substrate (12) or any other suitable material (such as for a focusing lens), the coating (10) extends the useful life by helping prevent moisture adsorption that otherwise may occur within 2-3 days of contact with air. The coating (10) may comprise (1) a BaF2 layer (14) of approximately optical quarter wave thickness, (2) a thin 200-300 Angstrom layer of ThF4 (16) used as a water barrier (3) a thin 1000-2000 Angstrom layer of ZnSe (18), and (4) an optional ZnSe layer (20) of optical half wave thickness. Among other applications, the coating (10) provides very low energy absorption for a 10.6 um CO2 laser at a value<0.15%, and provides longer lifetimes as compared to conventional coated lenses without the combination of BaF2 (14) and ThF4 (16). The specific and relative thicknesses of the various coating layers can be modified substantially and still provide many benefits.

Dependencies are inferred from the claim text.