Bright-field kinematical conditions

Bright-field kinematical conditions are used when it is necessary to avoid the dynamical contrast effects seen in strong two-beam (dynamical) conditions. This is achieved by tilting the foil just away from the Bragg condition. As a result, the contrast is often easier to interpret,but quantitative measurements, such as the loop sizing, should be made with caution. 

Several different types of diffraction condition are used to characterise radiation damage. These are achieved by tilting the specimen with reference to the Kikuchi pattern. These include dynamical two-beam , bright-field kinematical and weak-beam conditions - see Jenkins and Kirk for a full description. Under dynamical two-beam conditions, small dislocation loops located close to foil surfaces exhibit black-white contrast (Fig. 9.3), and their symmetry can be used to determine the Burgers vectors and habit-planes. 

The conditions for kinematic diffraction [160] are best approximated in the weak-beam method, which consists of making a dark-field image in a weakly excited diffraction spot. The dislocation image then consists of a narrow bright line on a darker background. 

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