D. Svatos, F. Joyeux, D. Polack, . Phalippou, . Opt et al., 7 Results were first presented XRM '93 conference on X ray microcopy, This communication was accidentaly omitted from the conference proceedings, and the main result was reproduced in Ref, 1993.

. See, M. For-example, E. Born, and . Wolf, Principle of Optics Pergamon, p.262, 1964.