Development of fiber-optical microsensors for geophysical use

Summary form only given. Technologies related to the micro electromechanical systems (MEMS) has been remarkably progressed in this decade, and various kinds of microsensors have been developed using the MEMS technologies. Microsensors have a potential to drastically improve the geophysical instrumentation, because they have advantages in size, weight, sensitivity, mobility, and cost to the conventional sensors. Researchers in Graduate School of Environmental Studies, Tohoku University, Sendai, Japan, have been developing microsensors for geophysical use under the subsurface microsensing project since 1993. The microsensors can be employed in wide area including geophysical exploration, logging, seismic observation, prevention of disaster, and evaluation of structural integrity etc. In this poster presentation, the authors show principles behind a miniaturized fiber-optic hydrophone and an optical accelerometer. A Fabri-Perot interferometer, which consists of a half mirror at the edge of optical fiber and a full mirror on diaphragm, is fabricated using the MEMS technologies for the detection of dynamic pressure in water and acceleration in both sensors. The design concept, fabrication process, performance and future development plan are shown.