Method for correcting the beam intensity in an image recording apparatus using a multi-channel light modulator

A method of correcting intensities of signal beams from a plurality of light modulator elements in an image recording apparatus, each of said plurality of light modulator elements comprising a plurality of ribbon-like diffraction grating members for generating diffracted light beams and a normally reflected light beam, said method comprising:

• a selection step of selecting a group of modulator elements, each element of which is selected to be spatially separate from an adjacent one by a distance of n (integer) elements;
• a measurement step of measuring the beam intensities of said group of modulator elements at a time with a photodetector having a plurality of photodetector elements;
• a reselection step of selecting another group of modulator elements for measuring the beam intensities of said another group until all of said modulator elements are selected;
• and
• a calculation step of calculating correction data for all of said modulator elements.

An image recording apparatus for recording an image on a recording medium, comprising:

• a light source;
• a light modulator having a plurality of light modulator elements receiving light from said light source;
• a holding means for holding said recording medium which is exposed to signal light beams from said light modulator;
• a photodetector having a plurality of photodetector elements;
• a recording optics for bringing said signal light beams to said recording medium;
• a detection optics for bringing the signal beams from said light modulator to said photodetector at a time, the signal beams being subject to beam intensity correction;
• correction electronics for providing correction data to said light modulator;
• and
• a controller for selecting a group of said plurality of light modulator elements which are spatially separate from one another to obtain the beam intensity of each element of said group with no effect of light from neighboring elements, and sequentially reselecting one group after another until all of said plurality of light modulator elements are selected, wherein
• each of said plurality of light modulator elements comprises a plurality of ribbon-like diffraction grating members for generating diffraction light beams and a normally reflected light beam.