S1 NMIJにおける超音波計量標準の現状と強力水中超音波への拡張(特別講演1)

抄録

In this paper, the author shows about the development of ultrasonic standards and future works at National Metrology Institute of Japan (NMIJ). By the beginning of 2006, both ultrasonic power standard and ultrasonic pressure standard have been established. These standards will be used mainly for medical ultrasonic diagnosis and treatment. Recently, in the fields of sonochemistry and medicine, high-power and high-pressure ultrasounds have been used. However, the measurement standards have not yet been established not only in Japan but also other countries because of difficulties of the measurements. At NMIJ, we have begun to prepare some new researches for ultrasonic measurements and standards for high power and high pressure ultrasound. For ultrasonic power measurement, as conventional radiation force balance method cannot work correctly at high power ultrasound due to thermal effect or acoustic streaming, alternative methods should be required. The calorimetry method with distilled water may become one of the suitable methods. Robust and stable hydrophones used in high pressure ultrasound field will also become key devices for medical ultrasound and sonochemistry.