Photoacoustics - A nondestructive evaluation technique for thermal and optical characterisation of metal mirrorsSwapna Mohanachandran Nair Sindhu
, NAMPOORI V P N
, Sankararaman S
, 2018, original scientific article
Abstract: Photoacoustic technique has emerged as a powerful tool for nondestructive evaluation and characterization. The high signal to noise ratio, sensitivity, and the least quantity of sample required make the technique suitable for wide range of applications. The intensity modulated laser beam focused on to the sample in the photoacoustic cell generates acoustic waves. Analysis of the acoustic signal enables the measurement of thermal and optical properties of the material. In the present work, the photoacoustic technique has been extended to find the thermal diffusivity and to demonstrate how the technique can be used for measuring optical reflection coefficient of a precious metal mirror—Aranmula mirror. The mirror being metal with high reflection coefficient, it finds application in optical instrumentation. The mirror is subjected to morphological characterization by atomic force microscopy and field emission scanning electron microscopy. The elemental and structural characterizations are done by energy dispersive x-ray spectroscopy, X-ray dot mapping, and X-Ray diffraction analysis. The fractal dimension of the particle distribution over the surface provides information about the surface roughness. The box-counting and power spectral fractal dimensions are found to be around 1.63 and 1.65 respectively.
Keywords: Photoacoustics, Nondestructive evaluation, Aranmula metal mirror, Reflectivity
Published in RUNG: 30.06.2022; Views: 799; Downloads: 0
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