Acoustic time-frequency domain imaging

The axial resolution of conventional acoustic micro imaging is limited by the wavelength of acoustic waves. Acoustic time-frequency domain imaging was recently proposed to overcome the wavelength limit [Zhang et al., J. Acoust. Soc. Am. 118, 3706-3720 (2005)]. A continuous wavelet transform based acoustic time-frequency domain imaging technique is investigated in this paper. Experiments are performed on real 3D data collected from microelectronic packages. Results demonstrate the proposed technique reveals more image details and enhances the image contrast in comparison with conventional time domain imaging.