These two modulations relate directly to the cos k,r and sin k,r terms in the ordered and disordered sections of the Landau representation table.
The e modulation has a repeat of 3 nm and the f modulation has a repeat of 5 nm. These values would have had the same k value if the photographs were obtained from the same specimen.
An example of the e-type quantum order modulation, associated with ordering in the plagioclases. In Chapter 23,The Feldspars, 1974, NATO Advanced Study Institute, Manchester 1972, edited by W.S.MacKenzie and J.Zussman
Electron optical image of the quantum ordering modulation in a plagioclase feldspar of composition 55% Anorthite. Initially this specimen underwent spinodal decomposition, which is responsible for the coarser texture of the specimen. At a lower temperature of 800o C it then developed the extremely regular fine scale e-type incommensurate quantum modulation associated with ordering on the anorthite scheme. This photograph was obtained in dark field using the paired e satellites associated with ordering
An example of the f-type quantum disorder modulation in the plagioclases shown at the First Hallimond Lecture , 1970, on Electron-optical study of phase transformations, in Min.Mag. 1971,38, No 293, 1-20
My electron optical resolution of the disorder (f) modulation in a plagioclase feldspar of composition 70o Anorthite. This extremely regular disorder modulation was obtained using the direct beam 000 and the pair of associated f satellite reflections.