Working conditions on designing an X-ray phase plate using three-beam dynamical diffraction

Dynamical effects in three-beam X-ray diffraction are considered for the design of an X-ray phase plate to change linearly polarized X-rays into circularly and elliptically polarized ones. A working condition on selecting a proper three-beam diffraction is derived from the kinematical and the dynamical theories. Calculations on the intensities and phases of σ− and π-component waves are carried out based on the dynamical theory. An optics of realizing circular polarization is also proposed.