Application Of Sputtering To The Repair Of Metal Mirrors

Typical mirrors used in high power gas laser applications are of molybdenum construction and employ thin faceplates which overlay a multitude of narrow gauge cooling channels. Since such mirrors are extremely costly, it is desirable that they be refurbished rather than replaced when their surfaces are burned by laser radiation. However, the faceplates are quite thin (0.010 - 0.020 inch); allowing only a limited number of refurbishments by straightforward grinding and polishing techniques. To overcome this lifetime restriction, we have adopted a refurbishment procedure which employs the sputtering of pure molybdenum upon the damaged surface prior to grinding. In this manner it has become possible to resurface mirrors without reduction in structural integrity. Described are details of the techniques currently employed together with the precautions necessary for the production of defect free sputtered coatings.