Method for the Simultaneous Determination of Low Optical Bulk and Surface Absorption Coefficients in Solids.
DEPARTMENT OF THE AIR FORCE WASHINGTON D C
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A photoacoustic method of simultaneously determining optical bulk and surface absorption coefficients in solids in which a transducer is attached to the solid for measuring the amplitude of the acoustic wave generated by a beam of incident radiation as a function of distance of the transducer to the incident beam at a wavelength where bulk and surface losses, respectively, are heavily dominant. The transducer is chosen so as to give different functional dependencies for the bulk and surface absorption curves, respectively. The solid sample is also calibrated at wavelengths where bulk and surface absorption, respectively, are known. The output versus position or distance is measured at the wavelength of interest, and values of surface and bulk absorption coefficients are fitted to the respective pure curves so that they will add up to the experimentally generated composite curve. After the bulk and surface absorption curves have been determined for the wavelength of interest, the values of bulk and surface absorption coefficients can be determined by using the calibration constants found earlier. Author
- Solid State Physics