Abstract

The effect of ultraviolet irradiation on the visible and ultraviolet reflectance of silicon-oxide-protected aluminum mirrors was studied. The silicon oxide protective films were produced by evaporating silicon monoxide under various evaporation conditions. High deposition rates at low pressure result in films of true SiO which are absorbing in the ultraviolet and shorter wavelength region of the visible, and which are, therefore, unsuitable for protecting mirrors that are to be used in this spectral region. Films deposited at low rates and rather high pressures of oxygen (deposition rate <5 Å/sec at 8–10×10⁻⁵ Torr) consist predominantly of Si₂O₃, and exhibit strong absorptance only below λ=3000 Å. Their ultraviolet absorptance can be completely eliminated by ultraviolet irradiation from a quartz mercury burner. This makes it possible to produce well-protected aluminum mirrors with 92% reflectance down to λ=2200 Å. Infrared measurements have shown that the elimination of the ultraviolet absorptance of Si₂O₃ films by ultraviolet treatment is not caused by a conversion of Si₂O₃ into SiO₂. The reflectance of aluminum coated with true SiO is not affected by ultraviolet irradiation. Data on the solar absorptance of silicon-oxide-protected aluminum mirrors are presented.

© 1963 Optical Society of America

Effect of Ultraviolet Irradiation on the Optical Properties of Silicon Oxide Films

A. P. Bradford, G. Hass, M. McFarland, and E. Ritter
Appl. Opt. 4(8) 971-976 (1965)

On the Vacuum-Ultraviolet Reflectance of Evaporated Aluminum before and during Oxidation*

R. P. Madden, L. R. Canfield, and G. Hass
J. Opt. Soc. Am. 53(5) 620-625 (1963)

Optical Properties of Silicon Monoxide in the Wavelength Region from 0.24 to 14.0 Microns*

Georg Hass and Calvin D. Salzberg
J. Opt. Soc. Am. 44(3) 181-187 (1954)

Solar Absorptivity and Thermal Emissivity of Aluminum Coated with Silicon Oxide Films Prepared by Evaporation of Silicon Monoxide

A. P. Bradford, G. Hass, J. B. Heaney, and J. J. Triolo
Appl. Opt. 9(2) 339-344 (1970)

Reflectance and preparation of front-surface mirrors for use at various angles of incidence from the ultraviolet to the far infrared

Georg Hass
J. Opt. Soc. Am. 72(1) 27-39 (1982)