Reimer: Scanning Electron Microscopy contains a lot of information about this topic. many fundamental dependencies. A 3D angular distribution of BSE has been published in 2000 by Dirk Berger in his PhD (TU Berlin) in SEM (tilted and non-tilted samples). A very easy way is if you use EBSD detectors for the investigation of the anisotropy of BSE. There one of the fundamental papers have been published by O. Wells et al., Scanning 28 (2006),27-31. Currently, several groups are working in this field (including myself). Wrigth et al. published 2015 in Ultramicroscopy a very nice overview about possibilities. Mainly for imaging, but the principle is the same. 

Wells was also publishing a paper "Effects of collector takeoff angle and energy filtering on the BSE image in the SEM." Scanning 2 (1979)199-216 which also discusses the energy filtering.

Merli et al publihed "Spatial resolution and energy filtering of backscattered electron

images in scanning electron microscopy." Ultramicroscopy 88 (2001)139-150.

Deal et al. "Energy-filtered electron backscatter diffraction." Ultramicroscopy 108 (2008), 116-125 also tested an energy-filtered signal acquired by an EBSD detector.

Hi Gert,

             Can you please share the link of the references you mentioned  in the above amswer.