Optical noncontact dual-angle linear displacement measurements of large structures

An optical technique has been developed whereby two angles and linear displacement can be simultaneously measured in a noncontact fashion. The method depends upon the properties of diffraction gratings with linear variation of period along their length and photodetection using CCD arrays. The grating is attached to a structure at a point of interest while all other system components are placed at a remote location. Experimental results obtained using this technique are presented and compared with theory.