Sensitive Tint Visualization of Mode Variation of Lamb wave in the Gently Varying Thickness of Glass Plate

Propagation of ultrasonic Lamb waves in the glass having gently tapered part is visualized by the strobe photoelastic system introducing sensitive tint method. The time transition of ultrasonic pressure of 1.447 MHz burst sine wave propagation are observed. To enhance the contrast of ultrasonic Lamb wave, subtracted image with the C-MOS camera is adopted. As the results, polarities of ultrasound pressure are clearly visualized. As the Lamb wave propagate, higher mode of S2 mode of Lamb waves in the thick part are appeared and they are gradually varied to S0 mode in the thin part via the tapered part of S1 mode.