Patent ID: 6401349
Filing Date: 2002-06-11
Classification: G01B

Abstract:
Apparatus for measuring the profile of a surface, the apparatus comprising:a column having a longitudinal axis; a stylus mounting moveable along the longitudinal axis of the column; a stylus arm carrying a stylus, the stylus mounting and the stylus arm having cooperating elements which together define a pivot axis about which the stylus arm is pivotable relative to the stylus mounting to allow an angle of the stylus arm relative to the stylus mounting to vary from a substantially constant angle to enable the stylus to follow the surface during relative movement between the stylus mounting and the surface; a detector responsive to pivotable movement of the stylus arm to provide a detector signal having a value representing the angle of the stylus arm relative to the stylus mounting; a drive arrangement for receiving the detector signal, the drive arrangement being responsive to the value of the detector signal to move, when the detector signal does not have a predetermined value, the stylus mounting along the longitudinal axis of the column until the detector signal has the predetermined value so that, as a result of this movement, the stylus arm is maintained at the substantially constant angle relative to the stylus mounting; and a measuring device comprising an interferometer mounted at a fixed location for measuring the displacement of the stylus as the stylus follows the surface.