Ray tracing for holographic waveguides: image quality prediction in see-through systems

We present a sequential ray tracing tool, HoloTraceX, to evaluate, prior to experimental recording, the image quality of see-through waveguides formed by a glass substrate and two coupling/decoupling holograms. The model incorporates exact geometry, refractions and reflections with Fresnel coefficients, and volume holography using Kogelnik coupled wave theory to estimate ray efficiency. Wavefront maps and image metrics are calculated along the guided propagation, including chromatic dispersion and angular tolerances. Wavelength and angle scanning allows regions of high efficiency and low aberration to be identified, optimising the design of the couplers and the exit pupil. The results demonstrate that this preliminary analysis would optimise the holographic recording geared towards the optical architecture of see-through AR systems.