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Just an interesting question of semantics that annoyingly comes up from time to time when people are comparing x-ray beam diameters. What counts as "microbeam?" Of course "micro" has the precise meaning in SI as being a factor of 10^-6. The problem is that the prefix "micro" just means "extremely small" in common usage. The term is used very confusingly everywhere. Take microwaves. Microwaves have wavelengths from 1 millimeter to 1 meter. Go figure. They're just "extremely small" radio waves. Now I believe that it is more widely accepted that "nanofabrication" is making objects that are measured in nanometers. So shouldn't microbeams rightly be x-ray beams with diameters measured in microns (i.e. < 1 mm and >= 1 micron). Of course this makes all crystallography beams microbeams and everything smaller than 1 micron a nanobeam. That won't be popular. I've always called anything smaller than 50 microns microbeam because that's about as small of an aperture-based collimator as we could make. So a user should ask for "microbeam" if regular collimator is too large. I was always puzzled at the APS habit of calling this "minibeam", but it's starting to sound better all the time. But in practice, I think "microbeam" sometimes means "smaller beam than yours." So microbeam used to be 30 microns, 10 or 5, now maybe 1 micron. Pretty soon no microbeam at all. I think maybe I'll stick with "small", "smaller than usual", and someday "extremely small." I'd love to hear people's opinion on the topic. Richard Gillilan MacCHESS