| 摘要 |
PROBLEM TO BE SOLVED: To enable multi-layered by making use of a Bessel beam. SOLUTION: When collimating a laser light from a laser diode 1 into parallel light by a collimator lens 3 and converting it into an annular beam through a liquid crystal shutter panel 10, this optical head selectively turns ON and OFF respective annular parts of the liquid crystal shutter panel 10 to vary the diameter of the annular light beam, thereby enabling the depth-direction multi-layered recording of a recording medium 7. |
