Appeal No. 1998-2463 Page 7
Application No. 08/598,854
tracking, does not teach the use of wavelength variations to
accomplish it.”
We find that Andrews is directed to a raster output
scanner (col. 1, lines 5-11) which includes both facet
tracking and wobble correction (col. 12, lines 34-36). Facet
tracking (col. 3, lines 29-32) is brought about through the
use of a shifting structure for causing the laser beam to
follow the active deflecting facet as it rotates. In facet
shifting (col. 11, lines 37 and 38), the laser beam is shifted
in a direction
parallel to polygon rotation. In wobble correction (col. 11,
lines 35 and 36), the laser beam is shifted in a direction
perpendicular to the direction of rotation of the polygon
(Figure 6). In Andrews (col. 7, lines 29-31), an optical
element 50 is disposed in the pre-scan optics, between laser
12 and rotating polygon 16. The optical element 50, includes
(col. 7, lines 38-40) a cell containing a ferroelectric liquid
crystal material. Andrews further discloses (col. 8, lines 8-
17) that by applying a biasing voltage to the optical element
50, the refractive index of the optical element is varied,
resulting in the laser beam being deflected at an angle with
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