Simulation of microfocused image size from a one-bounce glass capillary

A new method of numerical calculation, based on geometrical optics for X-rays rather than ray-tracing, is developed to simulate the focal spot size and intensity gain from an elliptically-tapered one-bounce glass mono-capillary. Numerical results for a capillary designed for protein crystallography are in good agreement with experimental measurements and confirm a capillary slope errors limitation on the image quality.