beam_basis#

anri.geom.beam_basis(k_in_lab)[source]#

Return unit vectors along a beam and across it, horizontally and vertically, in the lab frame.

Horizontal is perpendicular to the beam and to lab z (the untilted omega axis); vertical is perpendicular to the beam and to horizontal. For a beam along lab x they are lab y and lab z. Beam divergence (ky, kz) and polarisation are defined along these directions, so they follow the beam wherever it points.

Parameters:

k_in_lab (Array) – [3] Direction of the incoming beam (need not be normalised; must not be vertical)

Returns:

  • k_hat (jax.Array) – [3] Unit vector along the beam

  • e_h (jax.Array) – [3] Horizontal unit vector across the beam, \(\hat{z} \times \hat{k}\) normalised

  • e_v (jax.Array) – [3] Vertical unit vector across the beam, \(\hat{k} \times \hat{e}_h\)