Multiple-shot laser damage thresholds of ultraviolet reflectors at 248 and 308 nanometers

Conference · Tue Jan 01 04:00:00 EST 1980

DOI:https://doi.org/10.1520/STP37017S· OSTI ID:6737385

Foltyn, S R; Newnam, B E

Multiple-shot damage thresholds of dielectric reflectors have been measured at 248 and 308 nm. Standard irradiation conditions were a 10-ns pulsewidth, 0.6-mm spot diameter and 35-Hz pulse repetition frequency. The reflectors, from various sources, were composed of oxide and fluoride films. Although damage was generally initiated at visible film defects, there was no correlation between damage susceptibility and the appearance of these defects. At levels near threshold, damage was most often observed as an increase in white-light scatter of a site with no growth upon continued irradiation; at higher levels, the damage site grew with successive shots. Test sites were subjected to at least 10/sup 3/ shots and some sites received as many as 2.5 x 10/sup 4/ shots; however, with only one exception damage was found to occur within the first few shots or not at all. Reflectors at 248 nm typically had damage thresholds in the 1.0 to 1.8 J/cm/sup 2/ range with two samples exhibiting unexpectedly high thresholds of 2.8 and 3.0 J/cm/sup 2/. In some cases, a subthreshold pre-irradiation treatment resulted in a 20 to 25% enhancement in damage resistance.

• Research Organization: Los Alamos Scientific Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6737385
• Report Number(s): LA-UR-80-3429; CONF-8009119-1
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700208* -- Fusion Power Plant Technology-- Inertial Confinement Technology
CARBON DIOXIDE LASERS
CHALCOGENIDES
COATINGS
CONFINEMENT
DEFECTS
ELECTROMAGNETIC RADIATION
FLUORIDES
FLUORINE COMPOUNDS
GAS LASERS
HALIDES
HALOGEN COMPOUNDS
INERTIAL CONFINEMENT
LASERS
OPTICAL SYSTEMS
OXIDES
OXYGEN COMPOUNDS
PLASMA CONFINEMENT
RADIATIONS
REFLECTIVE COATINGS
ULTRAVIOLET RADIATION