A systematic method for aligning double-focusing mirrors.

A comprehensive description of an alignment procedure for double-mirror (Franks) cameras is presented.* It is intended to serve as a practical laboratory guide. The method is summarized in a flow chart and illustrated by beam photographs and intensity profiles. Principals underlying the method are explained. Detailed procedures are given for the initial alignment of the mirrors, optimizing the focus and shape of the beam, adjusting the reflection and takeoff angles, defining and guarding the beam, and monitoring the process with a fluorescent screen, photographs and an X-ray counter. In the double-mirror sysstem, which was originally constructed by Kirkpatrick & Baez (1948) and developed by Franks (1955), X-rays emitted from a localized source can be focused by total reflection from two orthogonal curved mirrors to form small intense beams with narrow angular divergence. Double-mirror cameras are now commonly used for diffraction studies requiring high order-to-order resolution.