| 摘要 |
PURPOSE:To highly efficiently control a focus and tracking servo by forming an optical system holder with aromatic polyamide resin contg. glass powder and/or glass fiber. CONSTITUTION:Spiral springs 10 and 11 are provided on both ends of the neutral point retaining body 12 of an objective lens 1 fixed to an objective lens holder 2, a supporting shaft 13 fixed to a pedestal 20 is inserted in a circular hole 12a, circular holes 12b and 12c are fixed to ping 14 and 15 which are respectively fixed to the pedestal 20, and the positioning is completed. The whole material of the objective lens holder 2 is composed of aromatic polyamide resin mixed with glass fiber (30-60% content). Since the aromatic polyamide resin mixed with glass fiber is an electrical insulating material, an eddy current is not generated on the cylindrical part of the lens holder 2 when the objective lens 1 is driven in a focal direction. Consequently, the objective lens is precisely driven, and the focus tracking servo can be highly efficiently controlled.
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