International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

International Tables for Crystallography (2006). Vol. C. ch. 4.4, p. 437

Figure 4.4.2.5 

I. S. Andersona and O. Schärpff
[Figure 4.4.2.5]
Figure 4.4.2.5

Illustration of how a variation in the bilayer period can be used to produce a monochromator, a broad-band device, or a supermirror.