1.3 μm Laser Rate Calorimetry and Photoacoustic Studies of the Surface and Bulk Optical Absorption in CaF Single Crystal Samples
SourceThere are a variety of techniques for measuring the surface-to-bulk optical absorption ratio most of which require specially prepared samples. In most works only one technique was employed on a given sample. In this work we tried three different techniques to measure the surface-to-bulk optical absorption ratio, r, at 1.3 μm on a group of similar CaF2 single crystal samples. Laser rate calorimetry results on a series of samples of varying thickness gave r = βS/βB = 0.14 cm where βS is the surface absorption and βB is the bulk optical absorption in cm−1. A second slope was not seen on the long bar samples which implies that r is less than 0.3 cm. Analysis of photoacoustic chopping frequency variation studies using the Bennett-Forman theory gave r = 0.07 cm about half the multithickness result. Considering the experimental uncertainties all three technique yielded consistent results.