抄録
Germanium, aluminum, and stainless-steel plates were irradiated with a pulsed CO2-laser beam (10.6μm) focused to be 0.1 mm in diameter, and resulting optical acoustic signals were measured with a PZT piezoelectric element. Results indicate that deposits on the surface and internal damage can be detected from the signal magnitude and phase angle, effectively by using repetitivefrequencies more than 100 Hz.
