Effective Acoustic Media for GHz Ultrasonic Lens Focusing in Fourier Transform Application

This paper presents the analysis of effective acoustic media for GHz Ultrasonic Lens focusing in solid medium for the Fourier transform of Wavefront Computing (WFC) applications. An ultrasonic WFC module consists of an array of GHz ultrasonic transducers fabricated directly on CMOS on both sides of thick acoustic media, which includes two acoustic blocks and a flat acoustic lens sandwiched in between. Focusing of an acoustic wave, propagating in the acoustic blocks and the lens, depends on the medium of individual regions that it passes through. Suitable materials for the effective acoustic media investigated to achieve good focusing characteristics of the ultrasonic wave at the desired focal plane, and taking into account the impact of fabrication tolerance.