| 摘要 |
PURPOSE:To additionally reduce the size and thickness of the optical head by constituting a beam separating means for separating a reflected beam and exit beam so as to commonly have a function of a polarizing means to bend the progressing direction of the exit beam by about 90 deg. and the beam separating means so as to contain the polarizing prism and polarizing circuit means. CONSTITUTION:The exit beam from a semiconductor laser 1 is polarized by a polarizing prism and is converted from linearly polarized light to circularly polarized light by passing a quarter-wave plate 6. The circularly polarized light is made incident on an information medium surface 5. The reflected beam 8 is converted from the circularly polarized light to the linearly polarized light when the beam passes the quarter-wave plate 6. At this time, the polarization direction of the reflected beam 8 is perpendicular to the polarization direction of the exit beam 7. The incident reflected beam 8 on the polarizing prism 21 is polarized in a direction exclusive of about 90 deg. from a relation between the polarization direction of the reflected beam 8 and the optical axis direction 22 of the double refractive crystal constituting the polarizing prism 21 when the reflected beam 8 is reflected by the reflection surface 23. The exit beam 7 and the reflected beam 8 are thus separated. |
