Abstract: The invention relates to a tilt mirror arrangement which has at least one tilt mirror, a base and at least one mirror bearing having at least a virtually fixed pivot point between the tilt mirror and the base. The mirror surface is characterized by a length of less than 40 mm and the size of the entire arrangement of the tilt mirror, bearing and housing is arranged below the mirror surface so that the arrangement does not extend beyond the projection of the mirror plane or extends only insignificantly when the mirror tilts.

Abstract: The invention relates to a three-dimensional length-measuring device which employs optical interferometry and in which the comparator principle is satisfied as excellently as possible with respect to all three axes. For this purpose, a workpiece holder which is displaceable in orthogonal horizontal directions carries a three-dimensional reflecting body which defines a measurement space and is in the form of three mutually perpendicular adjacent mirrors (triple mirrors). Extensions of measurement beams with which the three-dimensional reflecting body is measured intersect at a point only slightly offset from the workpiece holder, and to obtain high thermal stability, the measurement table and the housing of the measuring device are made of a material of low thermal expansion.