| 摘要 |
PROBLEM TO BE SOLVED: To prevent return of a signal which leaks at a position of a filter to a light emitting part and to enhance communication accuracy. SOLUTION: An optical fiber 2, the light emitting part 5 and a light receiving part 6, etc. are provided to a casing 1. Then, a dielectric filter 7 transmits a transmission signal St emitted from the light emitting part 5, makes it incident on the optical fiber 2, reflects a light receiving signal Sr emitted from the optical fiber 2 and makes it incident on the light emitting part 5. In addition, a recessed part 8 for receiving light is provided to a peripheral wall part 1D of the casing 1 and the recessed part 8 for receiving light reflects a leak signal E in a direction different from an incident direction when the leak signal E is made incident on the recessed part 8 for receiving light when a part of the transmission signal St is reflected on a surface part 7A of the dielectric filter 7 and becomes the leak signal E. Thus, return of the leak signal E reflected on an inner surface of the casing 1 to the light emitting part 5 via the dielectric filter 7 is prevented and the transmission signal St is transmitted with high accuracy. COPYRIGHT: (C)2005,JPO&NCIPI
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