Quantitative determination of out-of-plane displacements by endoscopic electronic-speckle-pattern interferometry

The combination of endoscopes and electronic-speckle-pattern interferometry requires a more detailed consideration of their imaging properties with re spect to interferometric fringe formation, if a quantitative analysis of th e observed deformation is desired. Due to a relatively small distance betwe en the illuminating and the imaging optical elements and to strongly diverg ent beams, the sensitivity vector may not be regarded as constant, and imag e distortions caused by the endoscope optics must be taken into account. A simplified model that deals with the situation of a plane object perpendicu lar to the optical axes of the endoscope is presented and verified by exper imental results. (C) 2001 Elsevier Science B.V. All rights reserved.