Effect of electric field distribution on the morphologies of laser-induced damage in hafnia-silica multilayer polarizers
- Lawrence Livermore National Lab., CA (United States)
- Spectra-Physics Lasers, Inc., Mountain View, CA (United States)
Hafnia-silica multilayer polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The polarizers were designed to operate at 1064 nm at Brewster`s angle (56{degree}). They were tested with a 3-ns laser pulse at 45, 56, and 65{degree} incidence angle in order to vary the electric field distribution in the multilayer, study their effects on damage morphology, and investigate possible advantages of off-use angle laser conditioning. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies (pit, flat bottom pit, scald, outer layer delamination) were observed; they depend strongly on incident angle of the laser beam. Massive delamination observed at 45 and 56{degree} incidence, did not occur at 65{degree}; instead, large and deep pits were found at 65{degree}. Electric field distribution, temperature rise, and change in stress in the multilayer were calculated to attempt to better understand the relation between damage morphology, electric field peak locations, and maximum thermal stress gradients. The calculations showed a twofold increase in stress change in the hafnia top layers depending on incident angle. Stress gradient in the first hafnia-silica interface was found to be highest for 45, 56, and 65{degree}, respectively. Finally, the maximum stress was deeper in the multilayer at 65{degree}. Although the limitations of such simple thermal mechanical model are obvious, the results can explain that outer layer delamination is more likely at 45 and 56{degree} than 65{degree} and that damage sites are expected to be deeper at 65{degree}.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Laser Megajoules Project (CEA-DAM-DLP) (France); French Government, 75 - Paris (France)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 462883
- Report Number(s):
- UCRL-JC-124873; CONF-961070-8; ON: DE97051815; TRN: 97:010142
- Resource Relation:
- Conference: 28. annual symposium on optical materials for high power lasers - Boulder damage symposium, Boulder, CO (United States), 7-9 Oct 1996; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
OPTICAL EQUIPMENT
DAMAGE
COATINGS
LASER MIRRORS
ELECTRIC FIELDS
LASER RADIATION
POLARIZED BEAMS
LASERS
INFRARED RADIATION
PULSED IRRADIATION
LAYERS
HAFNIUM OXIDES
SILICA
ICF DEVICES