INFLUENCE OF THE GEOMETRY OF ILLUMINATION AND VIEWING BEAMS ON DISPLACEMENT MEASUREMENT ERRORS IN INTERFEROMETRIC METROLOGY

Out-of-plane interferometers are widely used in metrological investiga tions. Most of them use divergent beams to allow displacement measurem ents on a large dimension object and have a configuration which makes them sensitive to in-plane displacements. The limits of such systems a re described. The error for different interferometric configurations i s computed and solutions to correct it are proposed. It must be notice d that the error could be very large for some common configurations an d has to be corrected. (C) 1997 Elsevier Science B.V.