Recent improvements in PDS technique for low-absorption measurements

Marco Montecchi; Enrico Masetti; Gabriele Emiliani

doi:10.1117/12.20370

1 August 1990 Recent improvements in PDS technique for low-absorption measurements

Marco Montecchi, Enrico Masetti, Gabriele Emiliani

Proceedings Volume 1270, Optical Thin Films and Applications; (1990) https://doi.org/10.1117/12.20370
Event: The International Congress on Optical Science and Engineering, 1990, The Hague, Netherlands

Abstract

Photothermal Deflection Spectroscopy (PDS) is a recently developed technique that is finding a useful application in the measurement of low optical absorptance of thin films. Among the noise sources affecting the PDS measurement, probe beam pointing instability and mechanical vibration play a considerable role. In this work an optoelectronic system for the reduction of their influence is described. Moreover, PDS measurements are typically performed keeping the sample immersed in a deflecting liquid; thus measured values of absorptance must be corrected when other surrounding media, as air, are considered. This correction is an easy task for single film coatings. Here the general case of an unknown multiplayer coating is analysed; a range of values containing the true absorptance in air is obtained by theoretical analysis and a practical method to evaluate the absorptance in air is discussed. Finally, deflecting liquids alternative to the commonly used CCI4 have been examined. Useful optical range, thermal diffusivity and “relative deflecting power” of CCI4, CS2, Iso-octane and Aceton are reported.

Citation Download Citation

Marco Montecchi, Enrico Masetti, and Gabriele Emiliani "Recent improvements in PDS technique for low-absorption measurements", Proc. SPIE 1270, Optical Thin Films and Applications, (1 August 1990); https://doi.org/10.1117/12.20370

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