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
