SIMULTANEOUS IMPLEMENTATION OF LEENDERTZ AND DUFFYS METHODS FOR INPLANE DISPLACEMENT MEASUREMENT

Leendertz two-beam illumination and Duffy's two-aperture arrangements are two well established optical configurations in speckle interferome try for in-plane displacement measurement. However, the measurement se nsitivities of both these techniques are quite different. In Leendertz method the interbeam angle between the two illumination beams determi nes the sensitivity, while in Duffy's arrangement, it is governed by t he subtense formed by aperture separation at the object. In the presen t paper, we implement both these configurations simultaneously for in- plane displacement measurement. The proposed optical arrangement exten ds the range of in-plane displacement measurement considerably. Detail ed theoretical and experimental results are presented.