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We present a 3-D ultrasound imaging system utilizing a light-based ultrasound transmitter. The system achieves high spatial resolution through a plain surface coated with a thin layer of carbon nanotubes (CNTs), which is optically scanned by a pulsed laser. The transmitter is fabricated by depositing a CNT-polydimethylsiloxane composite onto a glass substrate using techniques such as dip coating, dropping, and spin coating. The transmission characteristics are dependent on the laser beam width and CNT layer thickness, with the spin-coated layer demonstrating a center frequency of 9.08 MHz and bandwidth of 12.65 MHz. The imaging system boasts an axial resolution of 200 μm and lateral resolution of 190 μm. 3-D imaging was successfully performed on a chicken heart with a penetration depth up to 30 mm, providing a potential replacement for complex high voltage pulser circuits with a simple and manufacturable optical ultrasound transmitter. [ABSTRACT FROM AUTHOR]

In this paper, we propose an acoustic block for widening the bandwidth and modulating center frequency of airborne transducers to improve the ultrasound imaging or metrology system. When acoustic block is attached, the characteristics of the ultrasonic transducer are changed by the squeeze film effect. Extra elastic and damping force are generated by squeeze film damping and can be changed according to parameters of acoustic block. For impedance matching, a CMUT vibrating in bending mode was used. The CMUT's FBW is 3.18 % and the center frequency is 103.5 kHz. We changed the area ratio of the acoustic block and attached it to the CMUT. The FBW was changed to 7.14 to 9.14 % and the center frequency to 108.7 to 112.1 kHz. With acoustic block, conventional transducers can be transformed into transducers with better performance in areas such as non-destructive testing and ultrasonic imaging. [ABSTRACT FROM AUTHOR]