| 摘要 |
PURPOSE:To smoothly perform sliding keeping away a foreign matter in the hole of a supporting shaft, and to attain an accurate and smooth position control for an objective lens, by forming a recessed part on one side of an objective lens holding member and the supporting shaft at a sliding part. CONSTITUTION:In a position control time, an objective lens holding member 5A is slided around and in the axial direction of a supporting shaft 3, however, by dropping the foreign matter, such as dust, etc., dropped and attached on the upper plan 503 of the member 5A in a recessed part 502, the member 5A can be slided smoothly against the shaft 3. Therefore, the position control for an objective lens 4 in the focusing and the tracking directions can be performed accurately and smoothly.
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