Charge coupled device apparatus having means for correcting for changes in the charge transfer efficiency of a charge coupled device

Charge coupled device apparatus comprising:

• a charge coupled device having an image array and an output;
• and
• means for correcting for changes in the charge transfer efficiency of the charge coupled device, comprising:
• synthetic reference image generating means optically coupled to the image array for applying initial and subsequent synthetic reference images to a preselected portion of the image array;
• and
• image processing means coupled to the output of the charge coupled device for comparing the subsequent synthetic reference images to the initial synthetic reference image to generate correction signals indicative of the differences therebetween, which differences are indicative of changes in the charge transfer efficiency of the charge coupled device, and for applying the correction signals to actual images generated by the charge coupled device to correct the relative position of the actual images in response thereto.

A method for correcting for changes in the charge transfer efficiency of a charge coupled device having an image array;

• said method comprising the steps of:
• generating an initial reference image in a preselected portion of said charge coupled device by providing a light source and means for guiding light from said light source to said preselected portion of said charge coupled device;
• storing said initial reference image in a memory;
• generating a subsequent reference image in said preselected portion of said charge coupled device;
• comparing said subsequent image with said initial reference image to determine the differences therebetween and generating centroid correction factors from said differences;
• and
• applying said correction factors to an image from the image array of said charge coupled device to correct for changes in the charge transfer efficiency of said charge coupled device.

A method for correcting for changes in the charge transfer efficiency of a charge coupled device having an image array;

• said method comprising the steps of:
• generating an initial reference image in a preselected portion of said charge coupled device;
• storing said initial reference image in a memory;
• generating a subsequent reference image in said preselected portion of said charge coupled device;
• comparing said subsequent image with said initial reference image to determine the differences therebetween and generating two orthogonal correction factors from said differences;
• and
• applying said correction factors to an image from the image array of said charge coupled device to correct for changes in the charge transfer efficiency of said charge coupled device.