Recent damage results on silica/titania reflectors at 1 micron
The results of several laser damage experiments involving 15 layer silica/titania high reflectors (HR) are reported. Damage testing was done using 1 ns laser pulses at 1.06..mu..m. The addition of a halfwave silica overcoat leads to a 50% improvement in HR damage threshold. An experiment to modify the electric field intensity distribution within the coating indicates that the determining factor is neither the peak field within the titania layers, nor the average field in the titania layers, but that the field at the titania/silica interface is important. An attempt to correlate damage threshold with absorption met with partial success. For absorptance values above 100 ppM, there is a strong correlation between damage threshold and absorption. However, the absorptance below 100 ppM, it appears that damage threshold is not related to bulk absorption in the coatings. Optical microscopy supports this conclusion.
- Research Organization:
- Optical Coating Lab., Inc., Santa Rosa, CA (USA); California Univ., Livermore (USA). Lawrence Livermore Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5582524
- Report Number(s):
- UCRL-83919; CONF-7910130-1
- Country of Publication:
- United States
- Language:
- English
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