Sample evaluating method using interferometric techniques to evaluate laser induced thermal expansion displacement of a sample

摘要

When evaluating defects, etc. of a sample by measuring thermal expansion displacement on the surface of the sample, which is produced by irradiating thereto an excitation beam of which intensity is cyclically modulated, a measuring beam having the displacement frequency F1 is irradiated to the vibrating surface of the sample, and the reflection beam is interfered with a reference beam having the frequency F2. The beat wave signal E1 (Beat frequency Fb=F1-F2) is converted to a binary signal E2. Then, the sample is evaluated by signals which are obtained by giving a suitable processing to the binary signals. In addition, the optic axes alignment is eliminated by utilizing the excitation beam itself concurrently as measuring beam.