Circular polarization: Difference between revisions

Revision as of 11:56, 29 September 2024

Revision as of 13:01, 22 November 2024

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The handedness of polarized light is reversed reflected off a surface at normal incidence. Upon such reflection, the rotation of the [[plane of polarization]] of the reflected light is identical to that of the incident field. However, with propagation now in the ''opposite'' direction, the same rotation direction that would be described as "right-handed" for the incident beam, is "left-handed" for propagation in the reverse direction, and vice versa. Aside from the reversal of handedness, the ellipticity of polarization is also preserved (except in cases of reflection by a [[Birefringence|birefringent]] surface).

Note that this principle only holds strictly for light reflected at normal incidence. For instance, right circularly polarized light reflected from a dielectric surface at grazing incidence (an angle beyond the [[Brewster's angle|Brewster angle]]) will still emerge as right-handed, but elliptically, polarized. Light reflected by a metal at non-normal incidence will generally have its ellipticity changed as well. Such situations may be solved by decomposing the incident circular (or other) polarization into components of linear polarization parallel and perpendicular to the [[plane of incidence]], commonly denoted ''p'' and ''s'' respectively. The reflected components in the ''p'' and ''s'' linear polarizations are found by applying the [[Fresnel equations|Fresnel coefficients]] of reflection, which are generally different for those two linear polarizations. Only in the special case of normal incidence, where there is no distinction between ''p'' and ''s'', are the Fresnel coefficients for the two components identical, leading to the above property.

[[File:Reversal of handedness of circularly polarized light reflected by mirror 2s.gif|thumbnail|A 3-slide series of pictures taken with and without a pair of MasterImage 3D circularly polarized movie glasses of some dead European rose chafers (Cetonia aurata) whose shiny green color comes from left-polarized light. Note that, without glasses, both the beetles and their images have shiny color. The right-polarizer removes the color of the beetles but leaves the color of the images. The left-polarizer does the opposite, showing reversal of handedness of the reflected light.]]