Real-time holography of ultrasonic surface waves

摘要: The holographic soundfield imaging technique combines the ultrasonic testing with interferometry. It makes possible subsurface of components. procedure results in an image that can be easily interpreted regard to detected flaws. Ultrasonic surface waves are induced into specimen and visualized by a real-time-image processing algorithm subtracts actual hologram from formerly stored without ultrasound. To get wave intensity modulation illuminating laser beam is triggered ultrasound source. Former investigations produced satisfactory concerning lateral resolution for bonding flaws cracks. Bonding down diameter 30% wavelength lying depths 60% incoming recognized. Recent development yields advantages real-time holography mainly because shorter time. Furthermore, this single allows generation several images different frequencies varying propagation directions. sound disturbed interaction between flaw. Thus, evaluation components during wave. Nowadays perform two irradiation directions one using 300 kHz up 2 MHz. An amplitude about 10 nm required attain good contrast value pattern.© (1996) COPYRIGHT SPIE--The International Society Optical Engineering. Downloading abstract permitted personal use only.