Abstract
The X-ray scattering amplitude for a finite wave packet diffracted by a distorted crystal is calculated by the use of a previously formulated theory (M. Kuriyama: J. Phys. Soc. Japan 23 (1967) 1369). Only a limited portion of the crystal is responsible for scattering. The geometrical arrangement of this region is discussed in terms of an observation point on the crystal exit surface, an incident (glancing) angle and an observation (detector) angle. The accuracy of the results depends on the lateral size of the incident X-ray beam. The internal wave fields and paths of classical energy flow are also discussed from the viewpoint of the present formulation.