Optoelectronic transmitters for medical ultrasound transducers

Optoelectronics and fiber optics can be used to miniaturize and improve the flexibility of the transducer cable and handle of medical diagnostic ultrasound scanners. The reduction in size gains importance as 2-D array transducers with up to 1000 independent channels are incorporated in diagnostic ultrasound systems. The design, fabrication, and analysis of a photoconductive semiconductor switch (PCSS) is described. The monolithic silicon PCSS was used in combination with a pulsed infrared semiconductor diode laser with a fiber optic `pigtail' to shock excite and burst excite a 2-D array transducer element resonant at 3.5 MHz. Optically controlled transducer voltage and ultrasound pulses are displayed for single shock excitation and burst excitation