Absolute position measurement using optical detection of coded patterns

Discusses absolute, one- and two-dimensional position measurement using optical detection of coded patterns. A one-dimensional position transducer is described in which both absolute and incremental information are optically encoded on a single track. This concept is extended to a two-dimensional position encoder and both small-scale applications in instrumentation and large-scale applications in the navigation of guided vehicles are described. The performance of laboratory demonstration systems illustrates the feasibility of these concepts.