Optical System Overview - AGFA Avantra 36/44 Service Manual

2.10 Optical System Overview

The optical system divides into two basic sections:
• Spot generation module (SGM)
• Spin motor module
Several components, which all locate on a sub-base that mounts on the carriage
assembly, make up the SGM. The spin motor module also directly mounts to the
carriage assembly, which translates through the center of the drum.
A laser diode generates a modulated beam of red light under the control of the
laser diode driver electronics. This beam attenuates in a polarizer; one of four
apertures resizes and shapes the beam. Next, the weak lens/spot forming lens re-
focuses the beam to a small imaging spot. The spin mirror on the shaft of the spin
motor re-directs the beam 95 degrees away from the spin axis and sweeps the
imaging spot in a circular motion as the motor rotates at high speeds. As the imag-
ing spot sweeps across the inside of the drum, the entire optical system is traversed
through the center of the drum by the carriage assembly, writing onto the media
the information used to modulate the laser.
Figure 2-6 illustrates the optical schematic for the Avantra.
Figure 2-6 Avantra optical schematic.
–Laser diode. –Polarizer. –Aperature. –Spot forming lens.
–Spin motor mirror. –Image plane (film). –Drum surface.
Section I: Imagesetter
Functional Analysis 2-15