| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a correction element which can effectively correct anon-axis chromatic aberration during BD use while making three kinds of optical disks BD, DVD, and CD compatible through a common objective. <P>SOLUTION: An optical path difference imparting structure makes the quantity of diffracted light of X-th order of first luminous flux passed through the optical path difference imparting structure larger than the quantity of diffracted light of any other order, makes the quantity of diffracted light of 0-th order of second luminous flux passed through the optical path difference imparting structure larger than the quantity of diffracted light of any other order, and make the quantity of diffracted light of 0-th order of third luminous flux passed through the optical path difference imparting structure larger than the quantity of diffracted light of any other order. Consequently, even when the correction element is arranged in a common optical path that the first luminous flux, second luminous flux, and third luminous flux pass through so as to simplify an optical system, the on-axis chromatic aberration can be corrected using the diffracted light of X-th order with respect to only the first luminous flux, and use efficiency of light can be enhanced by passing the second luminous flux or third luminous flux through as it is. <P>COPYRIGHT: (C)2012,JPO&INPIT |
