International
Tables for Crystallography Volume B Reciprocal space Edited by U. Shmueli © International Union of Crystallography 2010 
International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 347
Figure 2.5.3.18
M. Tanaka^{f}


Figure 2.5.3.18
(a) Schematic diffraction pattern from a modulated crystal. As an example, the wave number vector of modulation is assumed to be k_{1}a*, k_{1} being an irrational number. Large and small spots denote fundamental and incommensurate reflections, respectively. (b) Incommensurate reflections are obtained by a projection of the Fourier transform of a (3 + 1)dimensional periodic structure. 