Fuji Xerox Phaser 5500 Service Manual page 59

The Laser Assembly is field replaceable and contains the laser diodes, scanner
motor/mirror, and several lenses and mirrors.
The Laser Assembly "reflects" the laser beam so it strikes the Drum.
Caution
Never remove the cover from a Laser Assembly for any reason - contamination
may result.
The Laser Assembly consists of four components: the Laser Diode (LD) Assembly,
the Scanner Assembly, Lenses and Mirrors, and the Start of Scan (SOS) board.
Laser Assembly Components
Component
Laser Diode Assembly
Scanner Assembly
Start of Scan Board
Theory of Operation
Start Of Scan
Function
Produces two laser beams that are turned on and off according
to the print data signal.
Consists of a faceted polygonal mirror mounted on the shaft of
the scanner motor that reflects the beams to the drum surface
through lenses and mirrors, to scan the beams across the drum.
When the laser beams strike the sensor on the SOS board, the
signal generated indicates the initial position of the scan. The
initial position where a scan is started on each line is detected.
Dual Beam Laser Diode
Polygon Mirror
Scanner Motor
s5500-030
2-19