Position gauge for measuring relative distance between two objects

摘要

The position gauge has a scale (14) on one object and a monitor (6) on the other which monitors the scale and is secured to a carrier (7) by an intermediate connector (12) enabling it to be moved longitudinally. The coefficient of expansion alpha AL of the intermediate connector is greater than the coefficient of expansion alpha ST of the carrier which in turn is greater than that of the scale. The intermediate connector is bonded to the carrier with a layer (13a) having a low Young's modulus, and the measurement scale is bonded to the intermediate connector with a further layer (13b) of which at least a part has a Young's modulus considerably greater than that of the other layer.