| 摘要 |
PURPOSE:To focus light beams which have been made incident upon the outside of a fiber, into a core, and to focus light beams radiated to the outside from a bend part of the fiber, to a light receiving optical fiber, by compensating a scattering phenomenon effect of a clad part and a covered layer by a hologram. CONSTITUTION:When a reference luminous flux 11 and a radiation luminous flux 12 have been superposed on a photosensitive material 13a, if an optical path difference of these luminous fluxes is below an intrinsic coherent distance which a light source 6 has, an interference fringe is formed on the photosensitive material 13a. The optical path length is given by the product of a distance through which light beams have passed and a refractive index of its medium. In this case, a passing distance of the reference luminous flux 11 is longer than a passing distance of the radiation luminous flux 12. On the other hand, a refractive index of an optical fiber is about 1.5, and higher than a refractive index (about 1) of air, therefore, the optical path lengths of the reference luminous flux 11 and the radiation luminous flux 12 can be allowed to coincide enough within a range of a coherent distance, and by developing the photosensitive material 13a to which a suitable exposure quantity has been given, a hologram is made. Also, by a type of the hologram, power can be concentrated on a main diffracted luminous flux. |
