Abstract: A tape rule assembly includes a linear optical encoder for sensing human-readable graduations of length disposed on a surface of a tape, without requiring any other machine-readable indicia to be present on the tape. The optical encoder includes two optical sensors disposed in a sensor holder pivotably disposed in the tape rule housing and configured to be displaced relative to one another in the housing along both the “x” axis and the “z” axis, a set of intersecting “x”, “y” and “z” axes being defined relative to a tape exit in the tape rule housing.