Displacement measuring system

Claim 1

A DISPLACEMENT MEASURING SYSTEM COMPRISING A SCALE HAVING SCALE DIVISIONS FORMED BY ALTERNATE STRIPS OF DIFFERENT LIGHT PROPAGATING PROPERTIES SPACED AT UNIFORM PITCH ALONG THE SCALE, SCALE LIGHTING MEANS, LIGHT UTILIZATION MEANS, AND A LIGHT REFRACTING BODY MOVABLE RELATIVE TO THE SCALE, CHARACTERIZED IN THAT SAID BODY IS DISPOSED BETWEEN THE SCALE AND LIGHT UTILIZATION MEANS AND HAS A PLURALITY OF REPETITIVE SETS OF MUTUALLY INCLINED REFRACTING PORTIONS, EACH SET BEING OPTICALLY JUXTAPOSED TO AN INTEGRAL MULTIPLE, INCLUDING ONE, OF SAID SCALE DIVISIONS, SUCH THAT LIGHT BEAMS FROM CORRESPONDING POINTS IN A PLURALITY OF SCALE DIVISIONS ARE REFRACTED TO SAID UTILIZATION MEANS AT DIFFERENT ANGLES THAN LIGHT BEAMS REFRACTED FROM A PLURALITY OF CORRESPONDING POINTS RESPECTIVELY SPACED LESS THAN ONE PITCH FROM THE FIRST SAID CORRESPONDING POINTS, WHEREBY SAID UTILIZATION MEANS MAY DISTINGUISH ACURATELY BETWEEN LIGHT REFRACTED FROM EACH SAID PLURALITIES OF CORRESPONDING POINTS DESPITE DEFECTS IN PARTICULAR SCALE DIVISIONS.