In the framework of geometrical optics, we show that the general ray-tracing formula for finding the direction of the diffracted rays for thin phase holographic optical elements located on any arbitrary continuous surface can be derived in a form similar to Fermat’s principle.
© 1997 Optical Society of America
P. J. Twardowski and J. Harthong, "Phase holographic optical elements and geometrical optics," J. Opt. Soc. Am. A 14, 1293-1296 (1997)