TM 5-6675-316-14
(19) Mounted in the same plane is another movable lens, the COllimator lens.
This lens is always kept one focal length away from the aerial image produced by the
enlarging lens. This means that the image leaving the collimator lens will be
projected as parallel light. The collimator lens is moved backward and forward on a
carriage driven by a helix screw and stepping motor. As in the case of the
enlarging lens, the microprocessor program determines the position of the lens by
feeding information on the required number of steps via the driver board to the
stepping motor. The combined movements of the enlarging and collimator lenses, as
determined by the values stored in the program, produce point sizes from 5.5 to 74.
2-18
