Patent ID: 6313956
Filing Date: 2001-11-06
Classification: G11B

Abstract:
An optical pickup apparatus for reproducing information from one of different kinds of optical information recording medium, each having a transparent substrate in different thickness, or for recording information onto one of said different kinds of optical information recording medium, comprising:a first light source for emitting first light flux whose wavelength is .lambda.1;a second light source for emitting second light flux whose wavelength is .lambda.2, wherein .lambda.2 is greater than .lambda.1;a converging optical system comprising an objective lens having an optical axis, a first portion, a second portion, and a third portion, the third portion being farther from the optical axis than the first portion, the second portion being provided between the first portion and the third portion, anda photo detector,wherein the first portion and the third portion are capable of converging the first light flux on a first information recording plane of a first optical information recording medium having a first transparent substrate of thickness t1 to reproduce information recorded in the first optical information recording medium or record information in the first optical information recording medium,wherein the first portion and the second portion are capable of converging the second light flux on a second information recording plane of a second optical information recording medium having a second transparent substrate of thickness t2 to reproduce information recorded in the second optical information recording medium or record information in the second optical information recording medium, wherein t2 is greater than t1,wherein the photo detector is capable of receiving light flux reflected from the first information recording plane or the second information recording plane, andwherein the following conditional formula is satisfied for an amount of the first light flux not less than 30% of the total amount of the first light flux passing the first portion:0.06.gtoreq.SC1/f1.gtoreq.0.002where, in case that the first portion converges the first light flux on a first information recording plane, SC1 is a sine condition dissatisfaction amount of the first portion of the objective lens for a light flux at a height in the first light flux, and in case that the first portion converges the first light flux on a first information recording plane, f1 is a focal length of the first portion of the objective lens for a first light flux.