| 摘要 |
PURPOSE:To improve SN, by arranging plural condensers to condense optical signals propagated through a space from a terminal, and selectively coupling optical fibers connected to the respective condensers with a photodetector. CONSTITUTION:An optical fiber F of which one end is optically coupled with a laser diode LD built in a terminal T is penetrated into a flexible tube CH and opposed to a lens fitted to the top of the tube. Condensers CO1-CO4 are arranged on a ceiling CE and coupled with an exchange EXC through optical fibers F1-F4. Light from the terminal T is penetrated into one of the condensers CO1-CO4 by operating the tube CH. The incident light is inputted to a detector DTE through one of the optical fibers F1-F4 and the exchange EXC and converted into an electric signal. At low SN, the optical signal is projected to other condensers to select a condenser having the highest SN. |
