Liu Ming-Chung, Lee Cheng-Chung, Liao Bo-Huei, Kaneko Masaaki, Nakahira Kazuhide, Takano Yuuichi
Thin Film Technology Center, Department of Optics and Photonics, National Central University, Chung-Li, Taiwan 32001.
Appl Opt. 2008 May 1;47(13):C214-8. doi: 10.1364/ao.47.00c214.
Antireflection coatings for 193 nm composed of low-index (MgF(2) and AlF(3)) and high-index (LaF(3) and GdF(3)) materials are deposited by the resistive heating boat method at a substrate temperature of 300 degrees C. The optical characteristics (reflectance and optical loss), microstructure (morphology and surface roughness), stress, and laser-induced damage threshold (LIDT) of the coatings are investigated and discussed. The related reflection at 193 nm of the four kinds of antireflection coatings is smaller than 0.2% and the optical loss is less than 0.15%. Of the fluoride antireflection coatings, AlF(3)/GdF(3) had the lowest stress value. Antireflection coatings with AlF(3) as the low-index material had higher LIDT values than when MgF(2) was used.
