SEDL / STP / STP911-EB / STP28995S

A Wide Spectrum Antireflective Coating for Silica Optics and its Damage Resistance at 350 nm

Yoldas, BE
Westinghouse Research and Development Center, Pittsburgh, Pennsylvania

Partlow, DP
Westinghouse Research and Development Center, Pittsburgh, Pennsylvania

Smith, HD
Westinghouse Research and Development Center, Pittsburgh, Pennsylvania

Pages: 10    Published: Jan 1985

Download this paper for $25 PDF (252K)          View License Agreement
Abstract

A wide-spectrum antireflective coating has been developed for fused-silica optics. This coating provides antireflectivity down to ∼300 nm on fused silica, increasing its transmission to better than 99%. The coating is a single-layer graded-index film applied from special polymer-oxide solutions. The graded index results from nonscattering porosity and tailoring of the pore morphology. Unlike state-of-the-art techniques, however, the method does not involve phase-separated glasses, not does it require etching for the creation of porosity. The damage thresholds of coated fused silica optics at 350 nm initially varied from less than 1 J/cm² to 9 J/cm². The main causes of this large variation in the damage threshold were investigated and determined to be substrate polishing, substrate surface cleaning, and coating solution chemistry and processing which, under certain conditions, leads to carbon formation during the heat treatment of the coating.