Damage Threshold Studies in Laser Crystals: Surface Damage, Prevention of Self-Focusing
Abstract
Initial experimental results on laser induced surface damage are discussed. The dependence of surface damage threshold on the distance between the focusing lens and sample indicates that surface damage for sapphire is a power density phenomenon. It is also pointed out that the exit surface damage threshold for sapphire is not connected with any nonlinear processes taking place deep within the bulk of the material, such as self-focusing. The relationship between surface plasmas and surface damage was also studied. The implications of these results are very important because they indicate that self-focusing can be avoided by choice of the appropriate beam shape. Theoretical considerations in this report have been concentrated mainly on a further pursuit of the question of whether optical breakdown does or does not involve an avalanche of hot electrons and also a consideration of means of measuring surface absorption at the faces of crystals so that the role of this absorption in surface damage may be assessed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1972
- Accession Number
- AD0740487
Entities
People
- Concetto R. Giuliano
- Gerald R. Rickel
- Robert W. Hellwarth
Organizations
- HRL Laboratories