COHERENT X-RAY-SCATTERING FROM AN OPTICAL GRATING

X-ray speckles due to scattering of partially (transverse) coherent x rays from an optical reflection grating are observed. The speckles ind icate the presence of surface inhomogeneities of the grating that are otherwise undetectable with either visible laser light or transversely incoherent x-ray scattering. Qualitative analysis of the speckle patt erns provide information on the surface morphology of the grating. The underlying order due to the periodicity of the grating enhances the d etection of the speckles. (C) 1998 American Institute of Physics.