| 摘要 |
PURPOSE:To obtain a bright objective lens for optical disc consisting of two lenses which is used most suitably when the distance from a light source to an information recording surface is short, by constituting the objective lens with the first lens having a positive refracting power and the second lens which has a positive refracting power and has both surfaces in the light source side and the image side formed to aspherical surfaces and arranging the first and the second lenses in order from the light source side and satisfying a specific condition. CONSTITUTION:The objective lens consists of the first lens having a positive refracting power and the second lens which has a positive refracting power and has both surfaces in the light source side and the image side formed to aspherical surfaces, and the first and the second lenses are arranged in order from the light source side, and the condition of a formula is satisfied. A condition (1) is given to determine the distribution of the refracting power of the first lens and indicates the range where aberration is corrected effectively by making the lens aspherical. Thus, the large-aperture lens for the short distance between the object and the image is obtained.
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