| 摘要 |
PURPOSE:To omit a collimator lens for turning light beams to parallel beams and to reduce the size of a device by forming a beam splitter unitedly with an objective lens and shielding excess light out of the light beams irradiated from a light emitting source at the peripheral wall part of an objective lens exposure opening part of a cover to cover an optical system member. CONSTITUTION:The objective lens 2 opposed to the surface of a recording medium disk 31 is arranged on the upper surface of a rectangular prism 1 and formed unitedly with a triangular prism 1, i.e. the beam splitter, or directly fixed with the prism 1. Another triangular prism 3 is sticked to one inclined surface of the prism 1 to constitute the beam splitter and a sealing prism. A convex lens 4 is sticked to the other side of the prism 1. Consequently, the optical path of the light emitting system is shortened and the whole size can be reduced. The cover 10 for protecting these optical system member is also provided with a function as a heat discharging plate for heat generated in the light emitting source 5, the opening part 11 for exposing a prescribed area of the objective lens 2 is formed on the upper wall and a diaphragm structure for shielding the excess light of the irradiated light from the light emitting source 5 is formed on the peripheral wall part. |
