| 摘要 |
PURPOSE:To correctly separate an incident beam and a reflected beam by providing a total reflection optical element and having a dielectric film on the whole surface of a glass substrate, on an optical path of a light beam genera tion source and a photodetecting part and an objective lens. CONSTITUTION:A reflected laser light beam from a disk D passes through an objective lens 6 and converted to a parallel luminous flux, and made incident on a total reflection prism 21. In the total reflection prism 21, the reflected laser light beam in the optical axis direction Ib is brought to a total reflection by a surface 22a side on which a dielectric film 23 is provided and which has an incident angle of 45 deg., the optical axis direction is denoted as Ia, and also, a P polarization component and an S polarization component of an orthogonal polarization component come to further have a phase difference by pi/2, and said beam is converted to a linearly polarized light from a circularly polarized light and made incident on a polarized light beam splitter 3 through a collimator lens 4, separated from the laser light beam from a beam generation source 1 reflected by an analyzer surface 3a and led to a photodetecting part 8. |
