On Tue, 08 Jul 2003 00:44:22 -0000, James Horn wrote:

By the way, non-reciprocal optical devices exist and are available. For
instance, if you have a two polarizers in parallel with their axes rotated
45 degrees from each other and put a polarization rotating medium between
them that rotates the light 45 degrees (a solution of sugar for home
experimenters), light travelling one way will only have the ganged
polarizer loss (about 50%) but the other way will see *crossed* polarizers
(over 99%). Small units for directional control in fiber optics are
available off the shelf.

Unfortunately for the original poster, however, such devices won't do what he
wants. I don't know of anything that can do this with white light that has
scattered off a random object (like a person) of varying color and texture.
There might be some exotic non-linear optical element like this, but certainly
not something the size of a normal mirror!

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com