| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for optical pickup which suppresses decline of use efficiency of light and can reduce change in performance by focusing. <P>SOLUTION: A luminous flux of a first wavelength λ is incident on the objective lens of an optical pickup PL1 as a nearly parallel light, and a luminous flux of a second wavelength λ2 is incident on the same as a limited divergent light. Wavefront aberrations on the luminous flux of the first wavelength λ and the luminous flux of the second wavelength λ2 are made within the diffraction limit by satisfying "-0.05<β<-0.01" wherein an imaging scale factor of the objective lens in the luminous flux of the second wavelength λ2 is set to β, and by correcting the wavefront aberrations on the luminous flux of the second wavelength λ2 by an aperiodic first step section 10 comprising multiple stages. <P>COPYRIGHT: (C)2007,JPO&INPIT |
