Abstract: An electronic micrometer having an encoding system located inside the micrometer housing for electronically determining and indicating the measurement made by the micrometer. The encoding system produces pulses in response to rotation of the micrometer thimble by having alternating reflecting and nonreflecting surfaces on the inside of the thimble which reflect pulses of light from a light source to a light sensitive cell. A digital counting circuit is provided for counting the pulses produced by the light sensitive cell and a digital readout for displaying the sum result. A system for sensing the direction of thimble rotation, and conditioning the digital counter to add or subtract pulses, has a light source and light sensitive cell opposite a reflecting surface which is either covered by a nonreflecting surface or uncovered depending upon the direction of rotation of the thimble.