Nonspecular phenomena in partly coherent beams reflected by multilayered structures

Abstract

Past studies determined that fully coherent beams undergo nonspecular changes on reflection by multilayered media. These changes involve lateral, focal, and angular shifts of the beam axis and a magnification of the beam width. By using Gaussian Schell-model beams, we examine such nonspecular effects in the case of partly coherent beams. We find that only the angular shift is affected by the presence of incoherence, while the other three nonspecular effects are identical to those in coherent Gaussian beams having the same waist size. On the other hand, we show that the coherence length, the far-field diffraction angle, and the degree of global coherence also are changed by the reflection process. However, all these nonspecular changes are correlated so that a specific combination of beam parameters is preserved as an invariant quantity.