From Wikipedia,
the free encyclopedia
Ewald's sphere is a
geometric construct used in
X-ray crystallography which
neatly demonstrates the
relationship between
- (a) the
wavelength of the incident
beams of light,
- (b) the
angle of diffraction for a
given reflection,
- (c) the
unit cell and
reciprocal unit cell of the
crystal, and
- (d) the distance between the
crystal and the film.
It was conceived by
Paul Peter Ewald, a German
physicist and crystallographer.
Ewald's sphere can be used to
find the
maximum resolution available
for a given wavelength of light
and the unit cell dimensions. It
is often simplified to the
two-dimensional "Ewald's circle"
model.
Ewald's sphere is also known as
the Ewald sphere.
