DECREASE IN SPATIAL COHERENCE OF LIGHT PROPAGATING IN FREE-SPACE

It is shown that a highly spatially incoherent light distribution may be generated from a highly coherent one on propagation in free space. This result essentially demonstrates that there exists an inverse of a classic result of optical coherence theory, namely, the van Cittert-Z ernike theorem. The analysis also indicates that the technique of phas e conjugation may be used to reverse changes in the coherence properti es of light, at least those which are generated on propagation in free space. (C) 1997 Optical Society of America.