Spatial partial coherence in Young's interferograms

Young's interferograms with high visibility reveals a high degree of spatia l coherence of first order. But, spatially partial coherence of second orde r can be observed when it interferes itself through a compensated Michelson 's interferometer attached at the exit of the Young's slit pair. We show th at the patterns at the exit of the Michelson's interferometer are Young's i nterferograms with modulation fringes, which allow an estimation of the deg ree of the high order spatial coherence. (C) 1998 Elsevier Science Ltd. All rights reserved.