Optical Constants and Reflectance and Transmittance of Evaporated Aluminum in the Visible and Ultraviolet*

The paper presents new measurements of the optical constants and of the reflectance and transmittance of evaporated aluminum films produced from the purest grade of aluminum with extremely fast evaporation at about 10−5 mm Hg. The optical constants were determined by Drude's polarimetric method from opaque films and by reflectance, transmittance, and true thickness measurements of semitransparent films. The following results were obtained. λ (mμ)220260300340380436492546578650n0.140.190.250.310.370.470.640.820.931.30k2.352.853.333.804.254.845.505.996.337.11R%91.892.092.192.392.692.692.291.691.590.7For extremely fast evaporated films the optical constants were found to remain unchanged down to film thicknesses of less than 100 A. Data are given on the reflectance and transmittance of semitransparent aluminum films on glass and fused quartz as a function of wavelength from 220 mμ to 650 mμ.