Ray Propagation in Beam-Waveguides with Redirectors

Correlated and uncorrelated transverse displacements of the lenses of a beam-waveguide 1 2 3 4 5 cause a propagating light beam to deviate from the axis of the guide. Since that deviation can grow proportionally to the number of lenses, the tolerance requirements on the lenses alignment become quite severe when the lenses are closelo spaced, as in beamwaveguides made with gaseous lenses. 67 In order to relax those tolerances, devices have been proposed that sense the position of the beam and introduce deflections tending to realign the beam with the guide axis.* In this paper, the steady-state ray trajectories of beams traveling in opposite directions through a sequence of misaligned lenses are derived for several possible arrangements of iterated redirectors. These calculations answer the following questions: (i) Considering a single beam and assuming that the displacement * Redirectors of this nature were proposed long ago by R. Kompfner and L. U. Kibler for beam-waveguides with widely separated lenses. 105