There is an Open Access version for this licensed article that can be read free of charge and without license restrictions. The content of the Open Access version may differ from that of the licensed version.
Pricing information
Please choose your delivery country and your customer group
Electron diffraction patterns from cold-rolled aluminum and chromium specimens showed sharply defined radial streaks, rather than spots, on each Debye-Scherer ring. These patterns were obtained using only the two condenser lenses of a Siemens Elmiskop 1 and with the second condenser aperture removed. Under these conditions, it is shown that the spherical aberration of the second lens partially concentrates the beam in a narrow annulus on the rim of the illuminated area of the specimen. The resulting low lateral coherence in this annulus causes the streaks. By adapting two-beam dynamical theory, the decrease of streak length with increasing radius of the Debye-Scherer rings was explained. The absence of streaks for fully annealed specimens is predicted. (Author)