X-ray interferometric moire fringes in the presence of temperature gradient within the frameworks of eikonal approximation

An expression for local period of interferometric moire fringes is obtained in the eikonal approximation. The earlier developed theory was employed for the case of temperature gradient in the mirror block of the interferometer. The geometric shape, the intensity distribution, and the dependence of local period of moire fringes on the coordinates were obtained. It was shown that in the direction of applied gradient the fringes are of purely dilatational type, while in the perpendicular direction they are of purely rotational type.