| 摘要 |
The objective lens drive apparatus according to the present invention includes a movable member which can be moved along a surface of an optical information recording medium an objective lens installed on the movable member, for allowing a light beam to pass and for concentrating the beam onto an optical information recording medium, a first diaphragm member installed on the movable member, having a first opening for determining the diameter of the light beam passing, and a second diaphragm member such that the second diaphragm member can be excluded from or inserted into the light path of the light beam and has a second opening for determining the diameter of the light beam passing.
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