| （英） |
Sensors that adopt electrooptic crystals, which are called EO sensors, have been utilized for detecting electric fields and signals with various frequency bands since a long time ago. Several EO sensors have already been commercialized by several manufacturers. However, we cannot definitely say that killer applications of EO sensors have already been found. To break this situation, we reconsidered both advantages and disadvantages of EO sensors. It is emphasized that EO sensors possess three advantages; large bandwidth, low invasiveness, and isolation. On the other hand, a remarkable disadvantage of EO sensors is poor sensitivity. We introduce novel application examples in which isolation nature of EO sensors is utilized. Recent year, systems that use electric of magnetic fields of MHz-frequency bands are actively studied. For example, these are intrabody communication and wireless power transfer. Electromagnetic fields used in such systems are not radiation but quasistatic. Owing to this fact, there exits severe problem that measurement apparatuses can easily change characteristics of the systems under test. Although it is difficult to correctly evaluate characteristics of such systems only with purely-electrical apparatuses, precise evaluation becomes possible by utilizing isolation nature of EO sensors. |