| 摘要 |
PURPOSE:To correct a tracking error of a scanning light beam at a high speed by adopting such the constitution that a collimator lens is moved as the scanning light beam is landed onto a prescribed scanning line. CONSTITUTION:A laser beam LA1 radiated from a light source 1 is converted into a collimated light by a collimator lens 2, converged as a scanning beam LA2 via an objective lens 6 to scan an optical recording medium 7. The reflected light LA3 is restored to a scanning position detector 9 via a beam splitter 3. Thus, if the landing position of the beam LA2 is deviated, a scanning position detection output S1 is obtained and a tracking control circuit 10 sends a tracking error signal S2 to a tracking drive section 21 accordingly. The drive section 21 uses the signal S2 to apply the moving control the lens 2 in a direction (a) orthogonal to the optical axis. The size and weight of the lens 2 is made small sufficiently comparing to those of a lens 6 then the lens 2 follows the signal S2 even if its speed change is made larger.
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