Hard Carbon Coatings For IR-Optical Components

Publisher Website
Google Scholar
Abstract
Amorphous carbon as an optical coating material offers the combination of extreme hardness, chemical inertness and transparency over a wide spectral range. Consequently, this material has found increasing interest as a protective AR coating especially for IR-optical components. We report on the rf-plasma deposition of hydrogenated amorphous carbon (a-C:H). Coating properties including density, hydrogen content, hardness, resistance against chemical at-tack, CO2 laser damage threshold, optical absorption and refractive index have been meas-ured and the dependence of most of these quantities on deposition parameters will be discussed. Of particular interest to the design of optical coatings is the possibility to adjust the refractive index of a-C:H between 1.8 and 2.2. As a result, quarter wave AR coatings on germanium for 10.6 µm (with a residual reflection below 0.2%) and hard carbon terminated multilayer AR systems have been realized. In addition, a-C:H is a promising coating material for HF, DF and CO laser applications, since absorption coefficients in the mid infrared as low as 10 cm-1 can be obtained.

This publication has 0 references indexed in Scilit: