| 摘要 |
PROBLEM TO BE SOLVED: To improve the availability rate of light while optimizing the characteristic of the light to be guided to a recording medium by providing a means for changing the diffusion angle of an incident light in a cover member. SOLUTION: A cover member 16 is attached to a shell 15. Moreover, the cover member 16 has a function preventing dirt and dust, etc., from sticking to a light guiding member 5 and a light receiving element or the like. The cover member 16 is consisting of a convex lens part 16b whose center part is swelled and a plate shaped part 16c and the part 16b has a function as a lens having workings converging an incident light, that is, a condensing action. Then, the diffusion angle of the light guided from a light source via the optical member and emitted from the light guiding member 5 is arbitrarily changed by changing the setting of the lens effect of the convex lens part 16b. Thus, almost the whole quantity of the light made incident on the cover member 16 is made incident on an objective lens and is guided to a recording medium. |
