부산대학교 도서관

To furnish a greater choice of film materials for application in optical multilayer coatings, the optical properties of evaporated rare earth compounds such as Y/sub 2/O/sub 3/, La/sub 2/O/sub 3/, Pr/sub 6/O/sub 11/, Nd/sub 2/O/sub 2/ , S m/sub 2/O/sub 3/, Gd/sub 2/O/sub 3/, LaF/sub 3/, NdF/sub 3/, and CeF/sub 3/ were studied in the wavelength region from 0.22 to 2 mu . The matertals were evaporated from tungsten boats and condensed on glass and fused quantz substrates at various temperatures. The optical constants n and k were determined mainly from reflectance, transmittance, and true thickness measurements. The following oxides were found to be useful because of their low absorption in the visible: La/ sub 2/O/sub 3/ with n ranging from 1.85 to 1.95 with increasing thickness, Pr/sub 6/O/sub 11/: with n ranging from 1.92 to 2.05, also with increasing thickness, and Nd/sub 2/O/sub 3/ with n = 2.05 for films of gufficiently low absorption. LaF/sub 3/ (n = 1.60 and NdF/sub 3/ (n = 1.61) showed no appreciable absorption in the whole wavelength region studied; CeF/sub 3/ (n = 1.63), however, exhibited two weak absorption bands at 0.234 and 0.248 mu . All n valued sre given at a wavelength of 0.5 mu and for unbsked films depodited at 300 mu C substrate temperature. The oxides condensed as almost amorphoug films, whereas the fluorides developed fairly large grains as indicated by their sharp electron dlffraction rings. All films were hard and showed excellent chemical and mechanical durability. (auth)