Advances in digital topography for characterizing imperfections in protein crystals

A system which joins digital topography with fine ϕ‐sliced reflection profiling has been developed and applied to cryocrystallography. In this demonstration, fifteen fine ϕ‐sliced reflection profiles with corresponding topographic sequences are evaluated: twelve reflections from a crystal at cryogenic temperatures and three reflections from a room‐temperature crystal. The digitally collected data show results comparable with film, albeit at a lower resolution, but are acquired at a substantially higher rate. Additionally, anti‐blooming circuitry in the CCD was tested and shown to provide useful data even when pixels were overloaded.