Editing Circular polarization (section)

=== From the point of view of the source ===

Using this convention, polarization is defined from the point of view of the source. When using this convention, left- or right-handedness is determined by pointing one's left or right thumb {{em|away}} from the source, in the {{em|same}} direction that the wave is propagating, and matching the curling of one's fingers to the direction of the temporal rotation of the field at a given point in space. When determining if the wave is clockwise or anti-clockwise circularly polarized, one again takes the point of view of the source, and while looking {{em|away}} from the source and in the {{em|same}} direction of the wave's propagation, one observes the direction of the field's temporal rotation.

Using this convention, the electric field vector of a left-handed circularly polarized wave is as follows:
<math> \left( E_x ,\, E_y ,\, E_z \right) \propto \left(\cos \frac{2 \pi}{\lambda} \left(c t - z \right),\, -\sin \frac{2 \pi}{\lambda} \left(c t - z \right),\, 0 \right) . </math>

As a specific example, refer to the circularly polarized wave in the first animation. Using this convention, that wave is defined as right-handed because when one points one's right thumb in the same direction of the wave's propagation, the fingers of that hand curl in the same direction of the field's temporal rotation. It is considered clockwise circularly polarized because, from the point of view of the source, looking in the same direction of the wave's propagation, the field rotates in the clockwise direction. The second animation is that of left-handed or anti-clockwise light, using this same convention.

This convention is in conformity with the [[Institute of Electrical and Electronics Engineers]] (IEEE) standard and, as a result, it is generally used in the engineering community.<ref>IEEE Std 149-1979 (R2008), "IEEE Standard Test Procedures for Antennas". Reaffirmed December 10, 2008, Approved December 15, 1977, IEEE-SA Standards Board. Approved October 9, 2003, American National Standards Institute. {{ISBN|0-471-08032-2}}. {{doi|10.1109/IEEESTD.1979.120310}}, sec. 11.1, p.&nbsp;61."the sense of polarization, or handedness ... is called right handed (left handed) if the direction of rotation is clockwise (anti-clockwise) for an observer looking in the direction of propagation"</ref><ref name=Orfanidis>Electromagnetic Waves & Antennas – S. J. Orfanidis: Footnote p.45, "most engineering texts use the IEEE convention and most physics texts, the opposite convention."</ref><ref>Electromagnetic Waves & Antennas – S. J. Orfanidis Pg 44 "Curl the fingers of your left and right hands into a fist and point both thumbs ''towards'' the direction of propagation"</ref>

Quantum physicists also use this convention of handedness because it is consistent with their convention of handedness for a particle's spin.<ref name="Lectures_on_Physics(Vol_1_ch_33-1)" >Lectures on Physics Feynman (Vol. 1, ch.33-1) "If the end of the electric vector, when we look at it as the light comes straight toward us, goes around in an anti-clockwise direction, we call it right-hand circular polarization. ... Our convention for labeling left-hand and right-hand circular polarization is consistent with that which is used today for all the other particles in physics which exhibit polarization (e.g., electrons). However, in some books on optics the opposite conventions are used, so one must be careful."</ref>

Radio astronomers also use this convention in accordance with an [[International Astronomical Union|International Astronomical Union (IAU)]] resolution made in 1973.<ref name=IAU>IAU General Assembly Meeting, 1973, Commission 40 (Radio Astronomy/Radioastronomie), 8. POLARIZATION DEFINITIONS -- "A working Group chaired by Westerhout was convened to discuss the definition of polarization brightness temperatures used in the description of polarized extended objects and the galactic
background. The following resolution was adopted by Commissions 25 and 40: 'RESOLVED, that the frame of reference for the Stokes parameters is that of Right Ascension and Declination with the position angle of electric-vector maximum, q, starting from North and increasing through East. Elliptical polarization is defined in conformity with the definitions of the Institute of Electrical and Electronics Engineers (IEEE Standard 211, 1969). This means that the polarization of incoming radiation, for which the position angle, q, of the electric vector, measured at a fixed point in space, increases with time, is described as right-handed and positive.'"</ref>