| 摘要 |
PURPOSE:To prevent a marginal light quantity from being short in case when a bright lens has been used, as well, by placing a fiber strand whose opening number becomes large gradually toward the peripheral part. CONSTITUTION:As for a fiber strand 2 constituting a bundle fiber 1, that which is gradually larger in its opening number (corresponding to dark hatching in the figure) is placed in the peripheral part. Accordingly, since the photodetecting angle becomes wider toward the peripheral part, even if the incident angle in the peripheral part becomes large due to use of a lens having a large aperture ratio, it can be led into the bundle fiber, a difference of light and darkness of the quantity of light between the center part and the peripheral part, of a transmission luminous flux is reduced, and the quantity of light is equalized. |
