Abstract

The measurement of the absorption coefficient of highly transparent materials using Pinnow and Rich’s calorimetric technique requires that the material be fabricated into the shape of a cylindrical rod. Since crystalline materials are more readily fabricated into rods with a square cross section, Pinnow and Rich’s calorimetric technique is extended to such samples. This is accomplished by calculating the temperature distribution that is produced in a sample of material having a square cross section by the passage of a Gaussian light beam through the sample. A simple relationship between the sample surface temperature and its absorption coefficient is derived that is valid to within 2% of the exact relationship for typical conditions that occur when employing the calorimetric method. The results of a calorimetric measurement of the absorption coefficients of a single crystal of potassium dihydrogen phosphate at a wavelength λ = 1.06 μm are reported. These are shown to be in good agreement with values reported earlier that were obtained by U. S. Averbakh, I. A. Batyrea, and V. O. Bespalov using a spectrophotometric technique.

© 1973 Optical Society of America

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