Detection of dislocations in strongly absorbing crystals by projection X-ray topography in back reflection

X-ray projection reflection topography has been applied to a number of strongly absorbing crystals in order to find general rules for rendering dislocations visible. Single- and double-crystal schemes have been utilized. Considering direct images of dislocations and calculating the ratio of extinction to the absorption depth, we have established a quantitative criterion for detecting individual dislocations. It is shown that ordered dislocation arrangements are less sensitive to the restriction due to the absorption.