ABSTRACT
Chapter 20, Beam Combination with Polarization Ray Tracing Matrices, analyzes interactions of multiple wavefronts with similar and different propagation directions. As part of the ray tracing processes, the interaction of multiple exiting beams must be simulated to analyze the electric field at the output plane accurately and reliably. This chapter addresses methods to simulate the combination of overlapping wavefronts, polarization ray tracing matrices and optical path lengths, as preparation for analyzing polarization aberrations of sophisticated devices with multiple overlapping polarized beams, such as crystal polarizer in Chapter 22 and multi-order retarder in Chapter 26.
Many optical systems divide a light beam into two or more partial waves, operate on each of these beams separately, and interfere the beams at an output plane. Such systems include beam splitters, interferometers, achromatic retarders, Lyot filters, optical isolators, crystal polarizers and many others. All birefringent components generate multiple wavefronts due to double refraction. The exiting wavefronts can completely or partially overlap in case of a retarder, or split and not overlap in case of beam splitters. When these wavefronts do overlap at an output plane, the resultant wavefront is the interference between all the partial waves. The output plane could be a detector such as a CCD, an exit pupil, screen for viewing interferograms, a device to record an interference pattern or hologram, or a surface to be illuminated, perhaps with structured light. One of the many issues combining multiple wavefronts is the relative positions of ray grids and the necessity for interpolation for each eigenmode. When these wavefronts do overlap at an output plane, the resultant wavefront is the interference between all the partial waves.
