| 摘要 |
PURPOSE:To prevent an offset due to deviation of a beam being a tracking error from being caused by tilting a light member whose incident face and emitting face receiving/giving a beam are formed in parallel to the beam and providing a drive mechanism moving the beam in parallel in tracking with the displacement of the objective lens to an optical system main body of an optical pickup. CONSTITUTION:A beam of a linearly polarized light radiated from a laser element 11 provided to the optical system main body 10 is subjected to circular parallel luminous flux in the luminous quantity distribution by a collimator lens 12 and a shaped prism 13, a circularly polarized light by a 1/4 wavelength plate 15 via a polarized beam splitter 14 and the result is made incident in the light refractive member 31. The member 31 is titled by the drive mechanism 32 in response to the displacement of the objective lens 20, the beam is moved in parallel and a spot is formed on a disk D. In this case, the objective lens 20 is moved by Xmm in the radial direction C and displaced on a position shown in broken lines, a current is injected to the drive mechanism 32 in response to the current injected to an actuator 21, the beam transmitted through the member 31 is moved by Xmm in parallel in the same direction and the optical axis of the objective lens 20 is made coincident with the center axis of the beam.
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