| 摘要 |
An optical tape pick up unit includes a holographic optical element and an aspheric objective lens. The holographic optical element splits a laser beam into first order beams and introduces pre-compensating wavefront error into the first order beams. The aspheric objective lens focuses the first order beams onto optical tape and introduces wavefront error into the first order beams having a magnitude similar to and polarity opposite that of the pre-compensating wavefront error. |
