peterobrien186
DarkStar
Here is an example of what crossed polarized light can and can't do.
The bright crystal is orientated between two crossed polarizing filters so that it's optically active and the light passing through the crystal is twisted and allowed to pass freely through the 2nd polarizer in the configuration. The colors arise from the degree of twisting as the light travels within the crystal. Whereas the dark crystal is presenting its basal facet, which is optically inactive, so the singularly polarized light passing through it is unaffected and is extinguished when encountering the other polarizer.
The fact you can see the dark crystal at all is from the scattered light from the brighter one.
DarkStar
Here is an example of what crossed polarized light can and can't do.
The bright crystal is orientated between two crossed polarizing filters so that it's optically active and the light passing through the crystal is twisted and allowed to pass freely through the 2nd polarizer in the configuration. The colors arise from the degree of twisting as the light travels within the crystal. Whereas the dark crystal is presenting its basal facet, which is optically inactive, so the singularly polarized light passing through it is unaffected and is extinguished when encountering the other polarizer.
The fact you can see the dark crystal at all is from the scattered light from the brighter one.