| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a magnetooptical head generally small in variation of numerical aperture and aberration due to interval variation. <P>SOLUTION: A magnetooptical head H is equipped with a first lens system L1 and a second lens system L2 for forming an optical spot on a magnetooptical disc 80 and, a lens barrel member 30 to which these first and second lens systems L1, L2 are fixed with spaces in-between. A lens 24 with a coil having a coil 25 for applying a magnetic field to the magnetooptical disc 80 is included in the second lens system L2, and the lens 24 with the coil is in proximity of the magnetooptical disk 80. When the numerical aperture of the whole lens systems consisting of the first lens system L1 and the second lens system L2 is NA, focal length of the whole lens systems is f, independent focal length of the first lens system L1 is f1, and β=f/f1, the first lens system L1 and the second lens system L2 are configured to satisfy 0.84≤NA≤0.9 and 0.3<β<0.39. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
