Diffraction by a finite crystal: general Laue-Bragg case - comparison with approximate extinction theories

After a comparison of Kato's theory of extinction with the conventional energy-transfer coupling model, it is shown that both models can be solved exactly for crystals with planar boundaries. Integrated reflecting power can be obtained analytically for a parallelepipedic crystal, which allows for a comparison with approximate treatments (such as the Becker-Coppens Laue formula or the infinite slab expression). For general geometric conditions, numerical integration may be needed. Respective usefulness of various models is discussed.