Patent ID: 7400408
Filing Date: 2008-07-15
Classification: G01B

Abstract:
1. An interferometric measuring device for measuring at least one of a shape, a roughness, and a clearance distance of a surface of a measured object, comprising: a radiation source; a modulation interferometer coupled to the radiation source, wherein a short-coherent radiation is supplied to the interferometer by the radiation source, and wherein the interferometer includes: a measuring probe spatially separated from the modulation interferometer and coupled to the interferometer by a light-conducting fiber set-up downstream from the modulation interferometer, wherein the measuring probe includes a probe-optical fiber unit having a slanted exit surface on an object side, the probe-optical fiber unit splitting the combined first beam component and the second beam component into a measuring beam guided to the surface and a reference beam, wherein the measuring beam reflected at the surface and the reference beam reflected at a reference plane are superposed; a receiver device coupled to the measuring probe for converting received radiation into electrical signals; and an evaluation device coupled to the receiver device for evaluating the electrical signals on the basis of a phase difference; wherein an angle of inclination of the exit surface to the normal of a longitudinal optical probe axis of the probe-optical fiber unit is at least 46°; wherein the probe-optical fiber unit includes a first section and a second section, the second section being proximate to the measured object, wherein an exit surface of the first section slants at an exit angle with respect to an optical probe axis of the probe-optical fiber unit, and wherein an entrance surface of the second section slants at an entrance angle with respect to the optical probe axis, wherein a partially transmitting region in the form of a wedge-shaped gap is formed between the exit surface of the first section and the entrance surface of the second section, and wherein the exit surface of the first section and the entrance surface of the second section are inclined in the same direction with respect to the optical probe axis.