Modern CCD cameras that are typically produced in high volume for consumer and machine vision applications can be used as precisely calibrated image sensors. New CCD chips with on-chip micro lens arrays, however, have some characteristics that limit design choices where precise illumination uniformity is required. The micro lenses cause vignetting and limit the angular aperture of each pixel. This paper measures vignetting and consequent shading for a typical micro lensed CCD chip. Nevertheless, when properly designed, camera system employed these advanced CCd chips can be precisely calibrated with respect to face plate irradiance.
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