2018 Volume 57 Issue 4 Pages 422-425
Constant voltage excitation and its selection of voltage waveform and optical method are introduced into the imaging system for evaluating the thin sample such as electronic device. Information of surface vibration velocity on the piezoelectric transducer and sample are effectively used. Rectangular pulse having the time width of resonance period of transducer was adopted to cancel the mechanical ringing. Exciting efficiency of transducer was improved by lager than 20 dB compared to our previous study. Imaging for the thin brass plate with etched “3” character is clearly imaged using time difference mode. As the result of experiment, possibilities as a tool for evaluating the thin plate like solid sample around several tens of μm such as electronic devices are revealed.
