| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device of a thin type exceeding a physical limit without revising a working distance and the number of an aperture. SOLUTION: Light 3 outgoing from a radiation light source 1 such as a semiconductor laser and converted to parallel light by a collimate lens 2 becomes light 5a made incident on a surface 4A of a prism 4 at an incident angle ϕ (angle formed by the incident light 3 for normal 4a of the surface 4A) and refracting at a refractive angle ψ (angle formed by the refracted light 5a for the normal 4a). This refracted light 5a is made incident on the surface 4B of the prism 4, is totally reflected on this surface, the reflected light 5b is made incident on the surface 4c of the prism 4, is reflected on this surface and the reflected light 5c is made incident again on the surface 4B of the prism 4 to be transmitted through this surface. This transmitted light 6 becomes convergent light 8 by an objective lens 7 and transmits through the surface 9B of an optical disk base material 9 to be converged on a signal surface 9A. |
