| 摘要 |
An optical pickup lens is provided to make the working distance long and to secure high on-axis and off-axis characteristics by forming a concave part at the outer periphery and a convex part in the center. An optical pickup lens(1a) for focusing the light flux emitted from a laser source, on an optical information recording medium is a single-focus type. A second surface(12a) opposite to a first surface(11) close to the laser source is formed in a continuum shape. First, second, and third radiuses(h1,h2,h3) from an optical axis to the outer diameter of the lens satisfy the following formula, h1<h2<h3. Each sag at the first, second, and third radiuses is sag1, sag2, and sag3. The change rates of each sag are Deltasag1, Deltasag2, and Deltasag3. The first, second, and third radiuses satisfy the following formula, 0>Deltasag1>Deltasag2 and Deltasag2<Deltasag3.
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