Patent ID: 6515284
Filing Date: 2003-02-04
Classification: G01N

Abstract:
Process for photothermally inspecting a test specimen in which the test specimen (58) is acted on by luminous radiation (65) in an illumination region (66) during an illumination time and thermal radiation (70) emitted by the test specimen (58) from a detection region (69) is detected, wherein properties of the test specimen (58) are determined from the chronological course of the thermal radiation (70), which can be represented by means of an emissions curve that has a heating part with an increasing amplitude and a cooling part with a decreasing amplitude, characterized in that at least two illumination times (tp) are adjusted, which are less than the quotient of the square of an estimated value of a layer thickness constituted by the distance between boundary surfaces and an estimated value for the diffusivity between the boundary surfaces, in that the illumination region (66) and the detection region (69) are spaced apart from each other with a diffusion spacing, in that the maximal amplitudes are determined for each emissions curve, which maximal amplitudes occur for each illumination time in the detection region, with associated adjustment times, and in that the diffusivity is determined from the ratio between at least two maximal amplitudes, the diffusion spacing, and the associated adjustment times.