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©1990-2002 J.Paul Robinson, Purdue University
Light Propagation & Vergence
•Considering a point source emission of light, rays emanate over 4pi steradians
•If the ray of light travels through a length L of a medium of RI n, the optical path length S=Ln (thus S represents the distance light woul dhave traveled in a vacuum in the same time it took to travel the distance L in the medium (RI n).
•Rays diverge (because the come from a point source
•Vergence is measured in diopters
Shapiro p 93
