I think there is a delay that could be minutes from the time of absorption to the time of re-emission as a statistical random manner in time and direction, thus preventing constructive interference to make a forward beam in the case of light absorbed by pigment. Chris. -----Original Message----- From: owner-photoforum@listserver.isc.rit.edu [mailto:owner-photoforum@listserver.isc.rit.edu]On Behalf Of Dan C Sent: 24 October 2002 15:47 To: List for Photo/Imaging Educators - Professionals - Students Subject: RE: Just how do filters work? It's actually much more complicated than that. Even clear glass absorbs all of the light that hits it. No photon actually gets all the way through a glass filter unimpeded. The photons are absorbed and remitted (in all directions) continually by all of the molecules that make up the glass. It is just by a miracle of optical physics (and very complicated mathematics!) that the re-emitted photons both constructively and destructively interfere with one another in just the right way so that the final outcome is an apparently identical bean of light exiting the sheet of glass (or filter). Look up "Extinction Theorem" in an adanced text on Optics, such as the one by Born and Wolf, if you really want the gory details. dan c. At 06:08 PM 23-10-02 +0100, Chris wrote: >The filter absorbs light of the unwanted wavelength. [snip]
