Optical coatings formed from amorphous oxide thin films have many applications in precision measurements. The Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo use coatings of
Amorphous tantala (
- NSF-PAR ID:
- 10130458
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Applied Optics
- Volume:
- 59
- Issue:
- 5
- ISSN:
- 1559-128X; APOPAI
- Page Range / eLocation ID:
- Article No. A150
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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(silica) and (titania-doped tantala) and post-deposition annealing to 500°C to achieve low thermal noise and low optical absorption. Optical scattering by these coatings is a key limit to the sensitivity of the detectors. This paper describes optical scattering measurements for single-layer, ion-beam-sputtered thin films on fused silica substrates: two samples of and two of . Using an imaging scatterometer at a fixed scattering angle of 12.8°, in-situ changes in the optical scatter of each sample were assessed during post-deposition annealing to 500°C in vacuum. The scatter of three of the four coated optics was observed to decrease during the annealing process, by 25–30% for tantala and up to 74% for titania-doped tantala, while the scatter from the fourth sample held constant. Angle-resolved scatter measurements performed before and after vacuum annealing suggest some improvement in three of the four samples. These results demonstrate that post-deposition, high-temperature annealing of single-layer tantala and titania-doped tantala thin films in vacuum does not lead to an increase in scatter, and may actually improve their scatter. -
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