Wave-front propagation: design code for synchrotron radiation beam lines.

Third-generation synchrotron radiation light sources provide partially coherent radiation. Certain topics in the optical design of beam lines and monochromators can be studied with electric-field distributions only rather than with intensity distributions of the light source. The radiation characteristics of a dipole or an undulator can be represented by a two-dimensional complex-electric-field distribution at a distance of several meters from the insertion device center. A method is described that transforms this field distribution through a complete beam line (consisting of mirrors and gratings) to the sample plane. Diffraction at apertures can be modeled and Stokes parameters can be evaluated. The derivation of the equations was performed with the algebraic code REDUCE. A comparison with the brightness formalism is provided.