| 摘要 |
<P>PROBLEM TO BE SOLVED: To precisely record or reproduce hologram indicating information on an optical disk. <P>SOLUTION: This disk drive can suppress the spherical aberration to the minimum by adjusting the distance D between the lenses in proportion to the cover thickness tc, and move the focusing points Fb1, Fb2 in proportion to the traveling distance of the moving lenses 61, 76 and at the same time make the spherical aberration minimum by properly designing the relay lenses 60, 75. Further, the sum of the cover thicknesses tc1, tc2 is always constant as long as the focusing points Fb1, Fb2 are at the same position. By utilizing these facts, and by moving the moving lenses 61, 76 of the relay lenses 60, 75 for the same distance in the directions opposite to each other depending on the desired depth, it can add each complementary spherical aberration to the blue light beams Lb1, Lb2, and correct the spherical aberrations at the focusing points Fb1, Fb2 to allow them to become the tolerance (0.02 λrms) or smaller. <P>COPYRIGHT: (C)2008,JPO&INPIT |
