| 摘要 |
A light focusing optical system focuses light, for recording to and/or reproducing from a plurality of optical recording media of different kinds, onto the recording media by using a diffraction element and lens. The diffraction element has at least first and second diffractive surfaces. The first diffractive surface diffracts light whose wavelength is 630 nm or more and 670 nm or less to perform aberration correction on an optical recording medium whose cover layer has a thickness of approximately 0.6 mm. The second diffractive surface diffracts light whose wavelength is 400 nm or more and 415 nm or less to perform aberration correction on an optical recording medium whose cover layer has a thickness of approximately 0.1 mm or approximately 0.6 mm.
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