Optoelectronic transmitters for medical ultrasound transducers

摘要

Optoelectronics and fiber optics can be used to miniaturize andnimprove the flexibility of the transducer cable and transducer handle ofnmedical diagnostic ultrasound scanners. The reduction in size has gainednimportance as 2-D array transducers with up to 1000 independent channelsnbecome accepted to improve diagnostic ultrasound images. The authorsndescribe the analysis, design, fabrication and testing of a prototypensilicon photoconductive semiconductor switch (PCSS). The monolithicnsilicon PCSS was used in combination with an infrared semiconductorndiode laser with a fiber optic “pigtail” to shock excite andnburst excite a 2-D array transducer element resonant at 2.5 MHz.nOptically controlled voltage, current, and ultrasound pulses arencompared to those from conventional electronic shock excitation andnnarrow band Doppler pulses. The optically triggered ultrasound pulse fornsingle shock excitation produced 30 V spikes at the 2-D array elementnwith a fall time of 200 nsec and a rise time of 2 Μsec with a peakncurrent through the transducer element of 34 mA. An optically producednburst of eight pulses at a frequency of 2.5 MHz produced 11 V spikes atnthe transducer with a fall time under 100 nsec and a rise time ofnapproximately 300 nsec. The peak current per pulse was 25 mA through thentransducer element. These results show the feasibility of applyingnoptoelectronic technology to replace conventional electronic transmitterntechnology