Dislocation contrast in X-ray synchrotron topographs

The contrast of dislocations in X-ray topographs taken in the Guinier-Tennevin mode with synchrotron radiation has been studied. In reflections where high orders were insignificant, dislocation images appeared very similar to those in Lang topographs taken with characteristic radiation. At large specimen-to-plate distances orientation contrast is important in the direct image. The sense of the Burgers vector of dislocations showing double contrast can be deduced.