Plotting apparatus and method utilizing encoded optical means

摘要

A plotting apparatus for plotting on a light sensitive material uses an optical head with an adjustable aperture plate to project a light beam through changeable apertures onto the light sensitive material. Encoding means are associated with the various apertures of the plate and comprise detectable indicia corresponding to the optical characteristics of the apertures. A detector on the optical head senses the indicia of the individual apertures as the plate is adjusted and sends signals corresponding to the identity of such characteristics to a control device responsible for adjustment of the plate or other component in the plotting apparatus.