an absolute optical linear or rotary encoder which encodes the motion of an object with increased resolution and encoding range and decreased sensitivity to damage to the scale includes a scale , which moves with the object and is illuminated by a light source . the scale carries a pattern which is imaged by a microscope optical system on a ccd array in a camera head . the pattern includes both fiducial markings which are identical for each period of the pattern and code areas which include binary codings of numbers identifying the individual periods of the pattern . the image of the pattern formed on the ccd array is analyzed by an image processor to locate the fiducial marking , decode the information encoded in the code area , and thereby determine the position of the object .