Wavelength#
In diffraction, the wavelength of the incident radiation sets the radius of the Ewald sphere. [1] Only \(hkl\) reflections which lie within the Ewald sphere are accessible to the experiment.
Note
While the energy of the incident beam may be interesting to diffractometer users at X-ray synchrotrons, wavelength is the general term used by diffraction science.
Here, a diffractometer (as a subclass of
DiffractometerBase) is a positioner that expects the
incident radiation to be monochromatic. Knowledge of wavelength is essential
for diffractometer operations. Simulators are provided for the general case
(Wavelength()) for any type of monochromatic
radiation) and for the case of X-rays
(WavelengthXray()) where photon energy is computed
from the wavelength.
When the wavelength (and possibly the energy) is known from EPICS, read-only
support is provided for the general case
(EpicsWavelengthRO()) and for a monochromator
(EpicsMonochromatorRO()) which provides both
wavelength and energy. Control of these EPICS PVs is beyond the scope of
diffractometer controls. Refer to EPICS for control of the monochromator or
wavelength PV. Or, create a custom subclass of
_WavelengthBase().
See also
The incident module.