Length or angle measuring apparatus

摘要

A length or angle measuring apparatus which measures the relative position of two objects comprises a scale attached to a first object to be measured and a scanning unit which has at least one scanning element connected to the second object to be measured, wherein the second object and the scanning unit have different thermal expansion coefficients. The graduation of the scale is scanning by a scanning element of the scanning unit at a scanning point. Fastening means are provided which fasten the scanning unit to the second object to be measured, such that the scanning point of the scanning element of the scanning unit has no zero point displacement with temperature changes.