| 摘要 |
PROBLEM TO BE SOLVED: To obtain an objective lens which is integrally molded with a bobbin part by the constitution of the objective lens of an optical pickup and whose condensed luminous flux diameter is regulated. SOLUTION: A recording and reproducing objective lens is provided with a level difference 3. The direction perpendicular to a refractive surface varies discontinuously at a position corresponding to the numerical aperture NA of an optical information required in accordance with the wavelength of a laser beam light source and information recording density on the refractive surface S1 of the objective lens 1 integrally molded with the bobbin 2 on a light source side. Thus, a luminous flux passing through a refractive surface in the more outside than the discontinuous part 3 is not condensed at an inside luminous flux condensing point, and the luminous flux diameter effective for recording and reproducing is regulated by the discontinuous part 3, so that condensed light having a specified numerical aperture NA is obtained.
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