| 摘要 |
PURPOSE:To improve resolving power and photoelectric current by facing the end face of an optical waveguide opposite to a reading object and providing two core layers having refractive index larger nearer the central part in the optical waveguide. CONSTITUTION:The end face of the optical waveguide of the image reading element in which the optical waveguide is used in the photodetecting system of images faces the reading object 2 and the optical waveguide has at least the two core layers 11a, 11b having the refractive index larger nearer the central part. Namely, more light can be taken into the entire part of the waveguide at the equal resolving power if the prospective angle to an original 2 is decreased by decreasing the ratio of the refractive index of the core layer 11b and the refractive index of the clad layer 12 near the side face at the end face of the optical waveguide and if the prospective angle to the original is widened by increasing the ratio of the refractive indices of the core layer 11a and the clad layer near the center of the waveguide. The end face type sensor which has the excellent stability of the resolving power and is further large in the quantity of the received light is obtd. in this way. |
