New stylus probe with interferometric transducer for surface roughness and form profiling

A prototype of a new stylus probe with an interferometric transducer for surface profiling is presented. Rotation of a measuring arm is transformed into electrical pulses by a multimode laser diode interferometer. A holographic grating laid on a cylindrical surface acts as a length master. The cylinder axis overlaps the rotation axis. Geometrical errors of the cylinder axis position relative to the rotation axis are analyzed. The influence of the offset of the measuring tip position relative to the measuring lever axis is emphasized. General characteristics of the device construction and metrological feasibilities of the prototype are presented. Resolution of 0.02 μm and nonlinearity error of ±0.05 μm in the measuring range of 7 mm are obtained.