| 摘要 |
PROBLEM TO BE SOLVED: To enable a light condenser to have a wide light receiving area at a low attitude by reducing the used amount of an optical fiber per unit light receiving area by condensing the light entering a casing through a light-transmissive member by means of a mirror having a long focal distance and introducing the reflected light from the mirror to the optical fiber by reflecting the reflected light by a curved-surface mirror having a short focal distance. SOLUTION: A casing has a side plate 33 surrounding an opening facing the bottom plate 31 of the casing and a light-transmissive member 36 closing the opening. In the casing, a first mirror 40a which condenses and reflects the light made incident through the member 36 and has a long focal distance and a second mirror 52 which receives the reflected light from the mirror 40a and has a small size and a short focal distance are provided. The front end face of an optical fiber 71 is faced oppositely to the second mirror on the optical axis of the reflected light from the second mirror 52. Therefore, an optical path is constituted from the light-transmissive member 36 to the optical fiber 71 through the first and second mirrors 40a and 52 and it is possible to make converged light incident to the light receiving end of the optical fiber at a relatively low incident angle even when the distance between the member 36 and bottom plate 31 is relatively short. |
