| 摘要 |
PURPOSE:To widen the range of the wavelengths to be used by inserting a multilayer film filter between the lens of a diffraction grating optical branching filter and a diffraction grating, newly providing a diffraction grating diffracting the reflected light thereof and so disposing the two diffraction gratings that they have the blaze angles conforming to the incident light and the angles that their normals and the incident light assume become tha blaze angles. CONSTITUTION:The incident light from an incident optical fiber 3 is made into parallel luminous fluxes by a lens 2. The light transmitted through a dielectric multilayer film filter 5 enters a diffraction grating 1 and the light reflected by the filter 5 enters a diffraction grating 1'. The diffraction gratings 1, 1' have beforehand been blazed to match the wavelength of the light incident thereto respectively. The diffraction gratings 1, 1' are so disposed that the angles that their normals and the incident light assume becomes the blaze angles. The monochromatic rays lambda1, lambda2,... diffracted by the diffraction gratings 1, 1' are transmitted or reflected through the filter 5, and are taken out from exit optical fibers 4 by the lens 2. Since two diffraction gratings are used, the range of the light that can be used is expanded. |
