| 摘要 |
PURPOSE:To detect a minute vibration whose amplitude is small by placing two semicylindrical refractive index distribution type lenses having a meridian surface so that meridian surfaces are opposed to each other in a distance which is below a distance as long as the wavelength of a light. CONSTITUTION:A light which is made incident to a semicylindrical refractive index distribution type lens 5 from an incident optical fiber 3 reaches a meridian surface of the semicylindrical refractive index distribution type lens 5. On this surface, the light is reflected, and made incident to an emitting optical fiber installed at a position of an image forming relation to an optical fiber 1. When a vibration 2 is applied to an exciting part 7, a distance between two semicylindrical refractive index distribution type lenses 5, 6 is varied, therefore, a reflection factor in the meridian surface of the semicylindrical refractive index distribution type lens 5 is varied in accordance with the vibration. Therefore, the coupling efficiency between the incident optical fiber 3 and the emitting optical fiber 4 is varied, and a light for propagating the emitting optical fiber 4 receives an optical intensity variation. An optical signal which has been subjected to an intensity modulation is detected by a photodetector and brought to a signal processing, by which the vibration is detected. |
