The recent use of single mode fibers in electronic speckle pattern int
erferometry (ESPI) shows that it is possible to produce a small and co
mpact system for the use even in a hostile environment, Standard singl
e mode fibers are easy to handle but cannot preserve the polarization
state of the input light when ambient conditions change during long te
rm measurements, The quality of the ESPI fringes decreases and the per
formance of the measuring system suffers, Under this point of view the
correlation of speckle patterns produced by light of different polari
zation states is investigated. (C) 1997 Society of Photo-Optical Instr
umentation Engineers.