Laser-damage susceptibility of nodular defects in dielectric mirror coatings: AFM measurements and electric-field modeling
Atomic force microscopy (AFM) and electromagnetic field modeling were used to study the influence of nodular coating defects on laser-induced damage of multilayer dielectric coatings. In studies of HfO{sub 2}/SiO{sub 2} mirrors with 1.06 {mu}m illumination, AFM results showed that nodular defects with high dome heights (>0.6 {mu}m) were most susceptible to laser damage. Crater defects, formed by nodules ejected from the coating prior to illumination, were not damaged when illuminated over the same range of fluences. A finite-difference time-domain electromagnetic modeling code was used to study the influence of 3-D nodule defects on the E-field distribution within the interference coating. The modeling results show that Enfield enhancements as large as a factor of 4 can be present at the defects. Crater defects, however, result in minimal enhancement of the E-fields within the coating. These modeling results are consistent with the AFM experimental data, indicating that E-field enhancement is a contributing mechanism in defect-dominated laser damage of optical coatings.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10159466
- Report Number(s):
- UCRL-JC-112981; CONF-9304144-1; ON: DE93014655
- Resource Relation:
- Conference: 2. international conference on laser ablation: mechanisms and applications,Knoxville, TN (United States),19-22 Apr 1993; Other Information: PBD: 15 Apr 1993
- Country of Publication:
- United States
- Language:
- English
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