| 摘要 |
PURPOSE:To simplify the construction, to make small and light the attenuator and to increase the accuracy of attenuation, by changing a relative interval between an optical fiber and a lens. CONSTITUTION:An incident light P1 given in parallel with an optical axis of a lens 1 by an optical fiber 4 is made incident to a boundary between the lens 1 and a medium 2 with an incident angle theta. An attenuation reflection light Pr is picked up through an optical fiber 5 and an attenuated transmission light Pt is picked up through an optical fiber 6. The optical fibers 4-6 are moved to positions shown in broken lines. That is, the interval between each light axis of the optical fibers 4, 5 and that of the lens 1 is changed and also the light axis of the optical fiber 6 and that of the lens 3a is changed, allowing to change the incident angle theta of the incident light P1 into theta'. As a result, the attenuation of the reflection light Pr and the transmission light Pt is changed in accordance with the change in incident angle and they are picked up respectively from the optical fibers 5, 6. |
