| 摘要 |
In order to optimum-correct, by a simple technique, wave front aberration generated even when such a technique as "a higher NA design" and "multi-layer recording" is used, an aberration correction element that can change a variable A and a variable B (A≠B) in a phase distribution expression A (-r<4>) -B (-r<2>) is realized by using a liquid crystal element (30) as an phase correction pattern by an aberration correction element. The liquid crystal element (30) forms, at one transparent electrode (31A), such an electrode pattern that can generate a phase distribution corresponding to spherical aberration, and, at the other transparent electrode (31B), such an electrode pattern that can generate a defocus pattern. The above variable A and variable B can be independently controlled by controlling voltages applied to these electrodes
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