gregg wrote in message <37c5fb73@news.povray.org>...
>Philip;
>Your attempt to model the physical behavior of a fresnel lens using POV-Ray
>is probably doomed to failure, even with the "photon patch", because a
>fresnel lens, unlike an ordinary glass lens, does not "bend" light by
virtue
>of slowing down light differentially along the radial axis, but by wave
>interference and the mutual interaction of an infinite number of spherical
>wavelets eminating from the disturbance, in this case, concentric circular
>grooves on a transparent substrate.

The Fresnel lenses I have seen have components that are so much bigger that
a light wavelength that this cannot be the effect causing the bending of
light.

>Since the photon patch probably relies
>on a simple particle model and not a wave model of light, it is doubtful
>that you will be able to reproduce this effect.

True, the photon patch uses the particle model of light, but as a Fresnel
lens works by bending light the same way that a normal lens bends light, and
the photon patch works just fine with normal lenses, the photon patch will
work with Fresnel lenses.

Mark

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