Method for photothermal materials testing on samples having rough or uneven surfaces, by means of the Mirage effect

摘要

In order to carry out photothermal materials testing on rough or uneven surfaces with the aid of the Mirage effect, it is necessary to compensate for changes in distance which are caused during the scanning between the scanning beam and the sample surface as a result of the condition (nature) of the surface and which influence the signal. This is achieved by optically determining the change in distance and by refocusing the light beam to minimal spot size with the aid of a motorised lens. The length of travel of the refocusing is assigned by computer to a signal change known from laboratory tests and can thus be separated from the signal changes due to the condition of the material.