Objective Lens and Optical Pickup Device

There are provided an optical pickup apparatus which can record/reproduce information properly at a time of temperature change or of using a multilayer disc, and an objective lens for use in the same. When temperature changes, spherical aberration resulting from a change in refractive index of objec...

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1. Verfasser: TOTSUKA HIDEKAZU
Format: Patent
Sprache:eng
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Zusammenfassung:There are provided an optical pickup apparatus which can record/reproduce information properly at a time of temperature change or of using a multilayer disc, and an objective lens for use in the same. When temperature changes, spherical aberration resulting from a change in refractive index of objective lens OBJ increases. Therefore, collimation lens CL is moved by uniaxial actuator AC1 in the direction of the optical axis, to make a finite light flux enter objective lens OBJ, which controls the spherical aberration. When a BD is a multilayer disc, spherical aberration also increases at a time of carrying out an interlayer jump from one layer to another in a plurality of information recording surfaces. Therefore, collimation lens CL is moved in the direction of the optical axis corresponding to the increase. The tilt sensitivity of objective lens OBJ is increased to handle that. Thereby, the occurrence of the third-order coma is effectively controlled even when a finite light flux enters objective lens OBJ.