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Published online by Cambridge University Press: 06 March 2019
The value of the divergent beam method as a powerful tool for investigating crystal perfection over rather wide limits has been known since the analytical work of K, Lonsdale. This method has been treated experimentally and theoretically by numerous authors and was popularized by Sigmund Weissmann. Although not nearly as useful as the reflection and transmission topographic techniques of Berg-Barrett and Lang for crystal characterization, it is potentially very useful for three dimensional quantitative strain analysis. The “technique phase” as Harvey Yakowitz remarked, is essentially over; however, refinements and optical improvements are certain to evolve if quantitative measurements are to become useful. Very short exposures and the non-destructive nature of the reflection divergent beara - Kossei method is a useful survey tool that has gained limited acceptance.
Presently, the reflection mode is useful in the qualitative survey of numerous semiconductor materials and processes, some of which have been considered from time to time by various authors. A range of crystal perfection, as well as some surface modifications, are surveyed. Kossel reflection pattern artifacts and irregularities are discussed.