Beams

The Beam class is the standard way to describing an x-ray beam. The following parameters are presently used by various functions in reborn:

\(E\) : The nominal photon energy

\(\lambda\) : The nominal photon wavelegnth

\(\Delta E/E\) : The nominal FWHM of photon energy

\(\Delta \theta_b\) : The nominal beam divergence FWHM

\(\hat{k}_0\) : The incident beam direction

\(\hat{E}_1\) : The primary polarization axis of the electric field

\(\hat{E}_2\) : The secondary polarization axis, equal to \(\hat{k}_0 \times \hat{E}_1\))

Code in the reborn package does not assume a “standard” beam direction, but the Beam class does set the default to \(\hat{k}_0 = (0, 0, 1)\) which we might call the \(\hat{z}\) direction. There is, however, one place where a beam direction is presently assumed: the diffraction viewers presently assume the default beam direction.