Method and system for calibrating spatial light modulator of imaging engine

Abstract

A calibration system for a platesetter or imagesetter is applicable to systems that have a media drum and a carriage, including a light source and a spatial light modulator for selectively exposing the media that is held against the drum. The invention can be applied to internal or external drum systems. The calibration system comprises a calibration sensor that is scanned relative to the spatial light modulator. The controller then analyzes the response of the calibration sensor to generate calibration information that is used to configure the spatial light modulator. The use of this calibration sensor allows for job-to-job calibration of the spatial light modulator, in one example, that ensures the generation of a high quality images, without banding, for example, on the media. This calibration system is also used to detect a best focus position for projection optics by measuring a contrast ratio between exposure and OFF light levels for various focus settings. It selects the best focus position in response to the contrast ratio.

Dependencies are inferred from the claim text.