A Novel Localized Coherence Rule Delay-and-Multiply Algorithm Toward Long-Range Ultrasound Imaging With Narrow Field-of-View pMUTs

This work proposes an innovative signal postprocessing algorithm for long-range ultrasound imaging by using a narrow field-of-view (narrow-FoV) lead zirconate titanate (PZT) piezoelectric micromachined ultrasonic transducer (pMUT) array. Two ${3} \times {3}$ mm2 dies of a 1-D array pMUT, whose resonant frequency is 6.5 MHz, consisting of 18 channels, were employed for this demonstration. The entire system has 18 channels by electrically combining two columns of pMUT membranes as one to increase the transmission power with the cost of narrowing FoV. In this work, experimental testing using single and multiple 5-mm diameter spherical reflectors at various arrangements was performed to validate the 2-D imaging capabilities of the developed pMUT array with the proposed image reconstruction algorithm achieving a 1.5-mm lateral resolution.