| 摘要 |
PURPOSE:To use a semiconductor laser which has lower power by making the surface of a beam splitter higher in refractive index in its outside area than at the center part where light is reflected. CONSTITUTION:The surface 5a of the beam splitter 5 is set high in refractive index at the outside with a luminous flux diameter phiB and the light which is incident on this part is reflected to a galvano-mirror angle detecting element (reflected light at this part is shown by a black arrow). Consequently, the beam splitter surface 5a can be set higher in transmissivity at the inside part with the luminous flux diameter phiB without reducing the light quantity in the angle detecting element. Therefore, the quantity of light traveling to a magneto-optic disk and an information detecting element increases, so the semiconductor laser having correspondingly low power is usable. |
