Accession Number : ADP002586

Title :   Hard Carbon Coatings for IR-Optical Components,

Corporate Author : FRAUNHOFER-GESELLSCHAFT FREIBURG (GERMANY F R) INST FUER ANGEWANDTE FESTKOERPERPHYSIK

Personal Author(s) : Bubenzer,A. ; Dischler,B. ; Koidl,P.

Report Date : 1982

Pagination or Media Count : 15

Abstract : Hydrogenated amorphous carbon films (a-C:H) were deposited on glass, silicon and germanium substrates. The films are transparent in the IR and are extremely hard. The a-C:H films were homogeneously deposited at a rate of about 500 A/min in an RF excited discharge from benzene vapour. The characteristic features of this deposition method are discussed. Thickness, short wavelength absorption, refractive index (2 - 10 micrometers) and relative hydrogen content were determined. Variations in short wavelength absorption, IR-refractive index and relative hydrogen content could be correlated with deposition conditions. The refractive index of a-C:H can be tuned to be exactly 2, thus a-C:H is an ideal single layer AR-coating for germanium (n = 4). Laser calorimetric measurements of optical absorption at 10.6 micrometers give an absorption coefficient of 250/cm. The application of a-C:H as single layer AR coating on Ge and as outside layer of a multi-layer coating is demonstrated.

Descriptors :   *Coatings, *Carbon, *Symposia, *Optical coatings, Films, Deposition, Substrates, Glass, Silicon, Germanium, Infrared optical systems

Distribution Statement : APPROVED FOR PUBLIC RELEASE