Abstract
We have developed an apparatus1,2 allowing precise positioning of the sample and simultaneous mapping of absorptance and scattering on a selected area with different resolutions. Photothermal deflection is used for measuring absorption while a low f-number lens collects part of the pump beam light scattered by the surface. The pump beam is focused on the sample through lenses of various focal lengths. Typically its gaussian beam diameter on the sample surface lies between 3 and 100 μm, according to the desired spatial resolution. By using centering tools and precise optical procedure, the sample positioning is reproducible with a precision of 1 μm. Recurrent mappings of the same area are possible either with the same resolution to study a sample at different stages of its life or with an increasing resolution for more detailed studies3. If thin film thermal properties are homogenous, the spatial resolution of the absorption mapping is about the size of the illuminated area which is therefore the same than that of scattering mapping, that is a value between 3 to 100 μm.
© 1998 Optical Society of America
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