Production of synchrotron X-ray biprism interference patterns with control of fringe spacing

An X-ray biprism has been constructed from a pair of rectangular-section polished diamond bars meeting edge-to-edge, and rotatable about the prism axis so as to vary the convergence of the refracted beams. Interference patterns have been recorded at wavelengths of 0.08, 0.096 and 0.11 nm with good agreement between calculated and observed fringe spacings. Application of the fringe-observing arrangement employed in this work to the assessment of X-ray source characteristics is proposed.