Absolute position measure with multi-beam optical encoding

An apparatus for measuring position along a ruler comprising, in combination,

• a. a measurement scale with encoding positional information along the length of said ruler comprised of a sequence of area elements whereby each said area element divides an incident first beam of radiative energy into two or ore second beams of radiative energy, where
• i. each of said second beams has a propagation direction substantially different from the propagation direction of any other said second beam and substantially different from the propagation direction of said incident first beam;
• ii. said propagation directions of all possible said second beams are predetermined;
• and
• iii. said area elements divide said first beam into a pattern of said second beams selectively in accordance with a code indicative of position along said ruler;
• b. a moveable reader traveling along said ruler comprising:
• i. one or more sources of radiative energy capable of producing and directing said first incident beams of radiative energy onto said area elements;
• ii. an array of radiation detectors to indicate said second beams of radiative energy;
• iii. means for displaying the outputs of radiation detectors as positional information.