| 摘要 |
PURPOSE:To make an optical head thin by providing a first surface having light beam splitting function and beam forming function, a second surface reflecting the light beam toward a recording medium and a third surface changing the direction of the returned light beam so as to be made incident on the second surface after reflecting by the first surface. CONSTITUTION:The first surface 3a crossing obliquely an incident light beam and having beam splitting function and forming the shape of the beam as an isotropical shape is provided. The second surface 3b is provided so that the light beam after forming the shape by the surface 3a is made incident at the angle larger than a critical angle and is changed the traveling direction toward a recording medium 6 placed in the perpendicular direction to the incident direction and the beam reflected by the recording medium 6 is returned to the first surface 3a passing through the same path as that of the outward path. The path of the beam reflected by the surface 3a is changed to the direction of the second surface 3b by means of the third surface 3c and is made parallel with the incident beam on the first surface 3a. Since a splitter 3 for setting the relation of the beams incident on and emerged from the beam splitter 3 as parallel and perpendicular is formed by one prism, thus, the device is miniaturized. |
