| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical information recording and reproducing apparatus capable of properly correcting spherical aberration occurring on each signal recording layer when using an optical recording medium with two high-density signal recording layers. <P>SOLUTION: An inter-lens distance of an beam expander 16 is set to three distances, and focus lamp operation is performed to each of the three distances; about a 1st signal recording layer L1, amplitudes of focal error signals S1 are measured; about a 2nd signal recording layer L2, the amplitudes of focal error signals S1 are measured ; about the 1st signal recording layer L1, the inter-lens distance of the beam expander 16 at which the focal error signals S1 become maximum is obtained based on the amplitudes of the three focal error signals S1; and about the 2nd signal recording layer L2, the inter-lens distance of the beam expander 16 at which the the amplitudes of the focal error signals S1 become maximum is obtained based on the amplitudes of the three focal error signals S1. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
