Fabrication and Performance of a Fiber Optic Micro-Probe for Megahertz Ultrasonic Field Measurements

抄録

For measuring high-frequency and intense ultrasonic fields, a miniature sensor with a durable structure has a great demand recently. The authors propose a new fabrication method of the small acoustic sensor which is composed of a micro optical cavity of 100 μm long at the end of an optical fiber. The deformation or the refractivity change of the cavity by sound wave is measured by monitoring the reflected light intensity at another end of the fiber. In this report, the fabrication technique of the sensing part is first described. Then, we examine the basic properties for measuring ultrasound in water. It is shown experimentally that megahertz ultrasonic field can be measured successfully by the prototype micro probe with a good spatial resolution.