# Circular polarization

circularly polarizedcircularly polarized lightcircularcircular polarisationcircularlycircular polarizedcircularly polarised lightcircularly polarisedhelicitiescircular basis
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.wikipedia
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### Polarization (waves)

polarizationpolarizedpolarized light
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.
In circular or elliptical polarization, the fields rotate at a constant rate in a plane as the wave travels.

### Elliptical polarization

elliptically polarizedellipticalaxial ratio
Circular polarization is a limiting case of the more general condition of elliptical polarization.
Other forms of polarization, such as circular and linear polarization, can be considered to be special cases of elliptical polarization.

### Waveplate

wave platequarter-wave platehalf-wave plate
To convert a given handedness of polarized light to the other handedness one can use a half-waveplate.
A waveplate or retarder is an optical device that alters the polarization state of a light wave travelling through it. Two common types of waveplates are the half-wave plate, which shifts the polarization direction of linearly polarized light, and the quarter-wave plate, which converts linearly polarized light into circularly polarized light and vice versa.

### Transverse wave

transversetransverse wavestransversal
The phenomenon of polarization arises as a consequence of the fact that light behaves as a two-dimensional transverse wave.
A wave produced by moving your hand in a circle or an ellipse is a circularly or elliptically polarized wave, two other special cases.

### Birefringence

birefringentdouble refractionbiaxial
Aside from the reversal of handedness, the ellipticity of polarization is also preserved (except in cases of reflection by a birefringent surface).
For instance, a quarter-wave plate is commonly used to create circular polarization from a linearly polarized source.

### Magnetic circular dichroism

Also, under the right conditions, even non-chiral molecules will exhibit magnetic circular dichroism, that is, circular dichroism induced by a magnetic field.
Magnetic circular dichroism (MCD) is the differential absorption of left and right circularly polarized (LCP and RCP) light, induced in a sample by a strong magnetic field oriented parallel to the direction of light propagation.

### Circular dichroism

CDcircular dichroism spectroscopyhelicity
The extent to which emissions are polarized is quantified in the same way it is for circular dichroism, in terms of the dissymmetry factor, also sometimes referred to as the anisotropy factor.
Circular dichroism (CD) is dichroism involving circularly polarized light, i.e., the differential absorption of left- and right-handed light.

### Linear polarization

linearly polarizedlinearlinear polarized
The other special case is the easier-to-understand linear polarization.
Circular polarization

### Fresnel equations

FresnelFresnel reflectionFresnel coefficients
The reflected components in the p and s linear polarizations are found by applying the Fresnel coefficients of reflection, which are generally different for those two linear polarizations.
checking that the final polarization was circular.

### Photon polarization

polarization transversalitylight polarization
In the quantum mechanical view, light is composed of photons.
can be described as having right or left circular polarization, or a superposition of the two.

### Plane wave

plane wavesplane-waveplane
Given that this is a plane wave, each vector represents the magnitude and direction of the electric field for an entire plane that is perpendicular to the axis.
Represented in the second illustration is a circularly polarized, electromagnetic plane wave.

### Optical rotation

optically activeoptical activityoptically inactive
In general, this phenomenon will be exhibited in absorption bands of any optically active molecule.
Whereas linear birefringence in a crystal involves a small difference in the phase velocity of light of two different linear polarizations, circular birefringence implies a small difference in the velocities between right and left-handed circular polarizations. Think of one enantiomer in a solution as a large number of little helices (or screws), all right-handed, but in random orientations.

### Helical antenna

helicalhelical antennasHelical (axial mode)
or helical elements:

### Dipole antenna

dipolehalf-wave dipoledipoles
A number of different types of antenna elements can be used to produce circularly polarized (or nearly so) radiation; following Balanis, one can use dipole elements:
A turnstile antenna comprises two dipoles crossed at a right angle and feed system which introduces a quarter-wave phase difference between the currents along the two. With that geometry, the two dipoles do not interact electrically but their fields add in the far-field producing a net radiation pattern which is rather close to isotropic, with horizontal polarization in the plane of the elements and circular or elliptical polarization at other angles. Turnstile antennas can be stacked and fed in phase to realize an omnidirectional broadside array or phased for an end-fire array with circular polarization.

### Mantis shrimp

stomatopodmantis shrimpsStomatopoda
Since then, circular polarization has been measured in several other scarab beetles like Chrysina gloriosa, as well as some crustaceans such as the mantis shrimp.
Rows 1 to 4 process colours, while rows 5 and 6 detect circularly or linearly polarized light.

### Scarabaeidae

scarab beetlesscarab beetlescarab
Since then, circular polarization has been measured in several other scarab beetles like Chrysina gloriosa, as well as some crustaceans such as the mantis shrimp.
Several members of this family have structurally coloured shells which act as left-handed circular polarisers; this was the first-discovered example of circular polarization in nature.

### Total internal reflection

critical angleinternal reflectiontotally internally reflected
If this light is then totally internally reflected back down, its vertical component undergoes a phase shift.
If the light is circularly or elliptically polarized, it will undergo the analogous Imbert–Fedorov effect.

### Polarization in astronomy

polarizationpolarizedDavis–Greenstein mechanism
According to the Davis–Greenstein mechanism, the grains spin rapidly with their rotation axis along the magnetic field.
Both circular and linear polarization of light from the Sun has been measured.

### Sinusoidal plane-wave solutions of the electromagnetic wave equation

planar light wave in vacuum
Sinusoidal plane-wave solutions of the electromagnetic wave equation
The polarization components can be linear, circular or elliptical.

### Polarizer

polarizing filtercircular polarizerpolarized
Polarizer
Circular polarizers, also referred to as circular polarizing filters, can be used to create circularly polarized light or alternatively to selectively absorb or pass clockwise and counter-clockwise circularly polarized light.

### 3D film

3D3-D3-D film
3D film
In the case of RealD a circularly polarizing liquid crystal filter which can switch polarity 144 times per second is placed in front of the projector lens.

### Classical electromagnetism

electrodynamicsclassical electrodynamicselectrodynamic
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.