Photopyroelectric spatially resolved imaging of thermal wave fields

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Abstract
Spatially resolved photothermal scanning imaging of metallic samples using the photopyroelectric (P2E) effect is reported. Unlike that for conventional photothermal detection, the new instrumentation involves polyvinylidene fluoride (PVDF) thin pyroelectric film and a metal-tip detection geometry, which permits monitoring of the local values of the laser-induced diffractive and/or interferometric thermal-wave field in a sample. The effects of the relative PVDF surface-tip position, of the laser beam modulation frequency, and of the presence of subsurface defects in the sample on the spatial resolution of the P2E images are examined.