| 摘要 |
An optical sensor which provides a focused elliptical illumination spot. The instrument includes a light source which provides a light beam that is directed through a cylindrical lens. The cylindrical lens focuses the light beam normally on a disk surface as an elliptical illumination spot with a major axis along a tracking direction and a minor axis along a scanning direction. Light scattered by the disk is then detected by a detector and processed to detect defects on the disk surface.
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