Optical measuring system measurement range is widened

An optical measuring system measurement range, which is determined by the width of a beam used to detect the measuring indicator position on a distance gauge, is widened by the provision of additional reference indicators of known spacing on the gauge. The measuring range of an optical measurement system, in which the range is determined by the width of a beam used to detect the position of a measuring indicator on a distance gauge, is widened by: (a) providing a series of reference indicators which are arranged transversely to the beam on the gauge at spacings of not greater than the measuring range and which are moved, together with the gauge, successively in or through the beam; and (b) determining the position of the distance gauge from the position of one or more of these reference indicators within the beam using an evaluation unit of the measuring equipment, the reference indicator measurement providing an offset value corresponding to its distance from the measuring indicator located outside the beam. An Independent claim is also included for equipment for carrying out the above process.