7 September 1999 Statistical distribution of optical losses in bare substrates and thin films through increasing spatial windows
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Abstract
The knowledge of the statistical and spatial distributions of optical absorption and scattering can give precious information about the size and the event frequency of the defects which may play an important role in laser damage for examples. The surface size to be characterized depends strongly on the application. A high spatial resolution is necessary to study micro defects while large areas have to be scanned to check the whole sample. In this paper we are interested first in multiscale studies of losses. We present some results in which we have changed the explored spatial window while keeping constant the spatial resolution. Furthermore we have tested the lateral spatial resolution of absorption mapping by photothermal deflection. A 5 micrometers - pattern with a high absorption contrast can be displayed by using a pump beam of 10 micrometers and a sampling step of 5 micrometers in spite of a probe beam of 28 micrometers . We have obtained the same result with a 3 micrometers -pattern of low absorption contrasts by using a pump beam of 3 micrometers and a sampling step of 2 micrometers . These experiments show that the spatial resolution is determined in a rough approximation by the pump beam diameter.
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Alexandre Gatto, Mireille Commandre, Pierre J. Roche, "Statistical distribution of optical losses in bare substrates and thin films through increasing spatial windows", Proc. SPIE 3738, Advances in Optical Interference Coatings, (7 September 1999); doi: 10.1117/12.360081; https://doi.org/10.1117/12.360081
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KEYWORDS
Absorption

Spatial resolution

Scattering

Laser scattering

Laser beam diagnostics

Associative arrays

Light scattering

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