A focusing X-ray camera for recording low-angle diffraction from small specimens

An X-ray camera is required in many low-angle diffraction experiments to focus the X-ray beam incident on the specimen. This paper describes an X-ray camera designed to record two-dimensional diffraction data from small specimens with unit cells as large as 50 nm. It matches the 200 μm focal spot of a rotating-anode X-ray generator to an electro-optical detector with a spatial resolution of 300 μm. The camera is very flexible and can accommodate a total source-to-detector distance of 2.5 m. The X-ray beam is focused by two 20 cm mirrors bent by simple two-point benders. The theory of such benders and the design of X-ray cameras incorporating them is discussed briefly. The paper also describes a fast (1 ms) X-ray shutter and simple ion chambers useful for alignment and operation.