| 摘要 |
The invention is directed to a method for cleaning surfaces of optical elements made from metal fluoride single crystals of formula MF2, where M is calcium, barium, magnesium, or strontium, or mixtures of the foregoing, prior to coating the elements with films of protective materials. The method has at least the steps of: immersing the optical element in at least one selected liquid and utilizing sonication at megasonic frequencies to remove particulates, polishing slurry residue and the damaged top layer of the optical element; cleaning in a gas phase cleaning process whereby hydrocarbons are removed from the surface of the optical element using UV/ozone cleaning; and exposing, in a gas phase process, of the optical element's surface to a low-energy plasma containing argon and oxygen in a vacuum environment. |
