| 摘要 |
PURPOSE:To eliminate light returning to optical fiber of light source side and improve S/N, by utilizing the reflected light from the plane of reflection of a reflector provided obliquely with respect to optical path, not utilizing the trasnmitted light as in the conventional method. CONSTITUTION:First and second optical fibers 1, 5 are placed on foci F1, F2 of lenses 2, 4 having the same focal length f. The light leaving the first optical fiber 1 is collimated by the first lens 2, and enters a reflecting film 6a on a disc form substrate 6 disposed at a certain angle to the optical path of this light. The light reflected by the reflecting film 6a is condensed by the second lens 4, and is coupled with the second optical fiber 5 at high efficiency. Since the reflectance of the reflecting film 6a is made to vary along the circumferential direction of the disc form substrate 6, the power of the light transmitted to the second optical fiber 5 may be freely adjusted by turning the disc form substrate 6 around a rotary axis 6c. Thus, because the substrate 6 is disposed obliquely, the reflected light from the substrate 6 does not return to the first optical fiber, so that no effect may be given to the light source side. |
