DEVELOPMENT OF HIGH FREQUENCY ULTRASOUND USING SAPHIRE FIBERS AS WAVE GUIDE

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(1) Transmission method of ultrasonic wave in the frequency range from few MHZ to 200 MHz using a sapphire fiber with diameters 100-200 microns was developed. The propagation loss in the fiber is extremely small. A conversion method from a transducer with a large diameter to the fiber was developed.(2) Preliminary results for the development of a biopsy-type microscopy were obtained. The sappire fiber was used as a waveguide to transmit the ultrasonic wave excited by the transducer placed outside the body to the tissue.(3) An ultrasonic motor using a helical coil as a stator was developed for IVUS(intravascular ultrasound). The structure of the motor is very simple. Therefore this motor may be used in medical engineering as well as industrial engineering.(4) Preliminary system for the IVUS was constructed and an image was obtained. The system incorporates the developed ultrasonic motor.(5) A method suppressing sidelobe level of the compressed pulse in pulse compression method in an intraductal ultrasonic imaging method was developed.