| 摘要 |
A raster scanning system is disclosed which utilizes a focus error correction system for correcting a focus error both in the fast-scan plane and in the cross-scan plane without affecting the scan characteristics of the post polygon optics. The focus error correction system comprises at least two axially adjustable lenses. One of the lenses is spherical and the other is cylindrical in the fast scan plane. The spherical lens has to be adjusted first to correct the focus error in the cross-scan plane. Next, the cylindrical lens should be adjusted to correct the focus error in the fast-scan plane.
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