Patent ID: 7127824

Claim:
A device for detecting a spatial position of a carriage, said device comprising: a prismatic reference standard having line gratings at least on one first and on one second surface thereof, at least one of said line gratings being a two-dimensional line grating, wherein the carriage is movable in a coordinate axis along a guide with respect to the standard, said standard extending parallel to the guide, and a position measuring system for determining a spatial position of a support member fixedly connectible with or integrated into the carriage, said position measuring system comprising: a first reading head and, spaced therefrom, a second reading head, which are provided on the support member and associated with a first one of the line gratings; a third reading head provided on the support member and associated with a second one of the line gratings; and a distance sensor for detecting the distance between the support member and one of the surfaces provided with a line grating or any surface parallel thereto; and wherein the support member is arranged on the carriage in such manner that the support member is prevented from contacting the reference standard during the detection operation.