A tape rule assembly , comprising: a housing having a tape exit , wherein intersecting "x", "y" and "z" axes are defined relative to the tape exit; a coiled length of tape disposed in the housing and having an indicia surface , and further being extendable from the housing along the "z" axis; a first plurality of human-readable graduations of length disposed on the indicia surface of the length of tape ; and a linear optical encoder disposed in the housing and operatively associated with the first human-readable graduations of length to provide an output representative of the length of tape extended from the housing; wherein the linear optical encoder includes two optical sensors ; the two optical sensors are displaced relative to each other in the housing along both the "x" axis and the "z" axis; and wherein the two optical sensors are configured to sense the first plurality of human-readable graduations of length ; characterized in that the tape rule assembly includes a sensor holder configured to hold the optical sensors , wherein: (i) the sensor holder is pivotably disposed in the housing about a horizontal pivot axis ; or (ii) the housing defines a recess , the sensor holder includes a member movable in the recess, and the sensor holder is configured to move via the recess; which sensor holder is configured to pivot, or move via the recess , responsive to undulations in the tape as the tape is extended from the housing and, together with a radial uncoiling bias generated by confining the coil of tape in the housing, is configured to maintain a critical distance (d) from the optical sensors to the indicia surface of the tape in an acceptable range (R), notwithstanding the undulations in the tape as the tape is extended from the housing. a housing having a tape exit , wherein intersecting "x", "y" and "z" axes are defined relative to the tape exit; a coiled length of tape disposed in the housing and having an indicia surface , and further being extendable from the housing along the "z" axis; a first plurality of human-readable graduations of length disposed on the indicia surface of the length of tape ; and a linear optical encoder disposed in the housing and operatively associated with the first human-readable graduations of length to provide an output representative of the length of tape extended from the housing; wherein the linear optical encoder includes two optical sensors ; the two optical sensors are displaced relative to each other in the housing along both the "x" axis and the "z" axis; and wherein the two optical sensors are configured to sense the first plurality of human-readable graduations of length ; characterized in that the tape rule assembly includes a sensor holder configured to hold the optical sensors , wherein: (i) the sensor holder is pivotably disposed in the housing about a horizontal pivot axis ; or (ii) the housing defines a recess , the sensor holder includes a member movable in the recess, and the sensor holder is configured to move via the recess; which sensor holder is configured to pivot, or move via the recess , responsive to undulations in the tape as the tape is extended from the housing and, together with a radial uncoiling bias generated by confining the coil of tape in the housing, is configured to maintain a critical distance (d) from the optical sensors to the indicia surface of the tape in an acceptable range (R), notwithstanding the undulations in the tape as the tape is extended from the housing. <EOS>