A high-precision method of measuring the reflectance of evaporated metal films is described and the results for aluminum and silver as a function of wavelength (visible to 13 microns) and angle of incidence (20° to 60°) are reported.
The apparatus was constructed as an accessory to the Perkin-Elmer Model 112 infrared spectrometer using an NaCl prism. A well-collimated beam of infrared radiation was reflected from two parallel glass plates of dimensions 3 inches by 10 inches which were coated with the surface to be measured. The intensity of the radiation after being reflected from the parallel mirrors 2, 4, 6, 8, and 10 times was recorded by the pen and ink recorder of the spectrograph and the reflectance was determined as a root of the ratios of these readings. The reflectances measured are accurate to 0.2%.
© 1958 Optical Society of AmericaFull Article | PDF Article
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