Mita DP-2800 Service Manual page 65

SIDE VIEW
1 Laser diode ...................................... emits diffused, visible laser.
2 Collimeter lens ................................. aligns the laser beam to the cylindrical lens.
3 Cylindrical lens ................................. compensates the slant angle at which the laser
4 Polygon mirror (motor) ..................... has ten mirror segments around its octagonal
5 Primary f-theta lens .......................... See below.
6 Secondary f-theta lens ..................... The primary (above) and secondary f-theta lenses
Drum
beam hits a polygon mirror segment.
circumference; each mirror corresponding to one
scanned line width on the drum when laser beam
scans on it.
equalize focusing distortion on the drum edges.
The effective length of line ("A," "B" below) the
laser beam draws on the drum becomes longer as
the laser beam hits closer to the drum edges. In
the figure below, distances represented by "A"
and "B" are not the same (A > B) until the f-theta
lenses are provided between the polygon mirror
and the drum (A' = B).
5A2
8
4-7