Physics
Polarisation
Polarization refers to the orientation of oscillations in a transverse wave, such as light or electromagnetic waves, in a specific direction. When a wave is polarized, its electric field oscillates in a particular plane, which can be vertical, horizontal, or at any angle. This phenomenon is crucial in various optical and communication technologies for controlling the direction of waves.
Written by Perlego with AI-assistance
Related key terms
1 of 5
12 Key excerpts on "Polarisation"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 2 Polarization (Waves) Polarization (also Polarisation ) is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves, such as light, and gravitational waves exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same. By convention, the polarization of light is described by specifying the orientation of the wave's electric field at a point in space over one period of the oscillation. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate either towards the right or towards the left in the direction of travel. Depending on which rotation is present in a given wave it is called the wave's chirality or handedness. In gen-eral the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space, the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes. For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 1 Polarization (Waves) Polarization (also Polarisation ) is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves, such as light, and gravitational waves exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same. By convention, the polarization of light is described by specifying the orientation of the wave's electric field at a point in space over one period of the oscillation. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate either towards the right or towards the left in the direction of travel. Depending on which rotation is present in a given wave it is called the wave's chirality or handedness. In general the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space, the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes. For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 2 Polarization (Waves) Polarization (also Polarisation ) is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves, such as light, and gravitational waves exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same. By convention, the polarization of light is described by specifying the orientation of the wave's electric field at a point in space over one period of the oscillation. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate either towards the right or towards the left in the direction of travel. Depending on which rotation is present in a given wave it is called the wave's chirality or handedness. In general the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space, the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes. For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 6 Polarization (Waves) Polarization (also Polarisation ) is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves, such as light, and gravitational waves exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same. By convention, the polarization of light is described by specifying the orientation of the wave's electric field at a point in space over one period of the oscillation. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate either towards the right or towards the left in the direction of travel. Depending on which rotation is present in a given wave it is called the wave's chirality or handedness. In general the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space, the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes. For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 1 Polarization (Waves) Polarization (also Polarisation ) is a property of certain types of waves that describes the orientation of their oscillations. Electromagnetic waves, such as light, and gravitational waves exhibit polarization; acoustic waves (sound waves) in a gas or liquid do not have polarization because the direction of vibration and direction of propagation are the same. By convention, the polarization of light is described by specifying the orientation of the wave's electric field at a point in space over one period of the oscillation. When light travels in free space, in most cases it propagates as a transverse wave—the polarization is perpendicular to the wave's direction of travel. In this case, the electric field may be oriented in a single direction (linear polarization), or it may rotate as the wave travels (circular or elliptical polarization). In the latter cases, the oscillations can rotate either towards the right or towards the left in the direction of travel. Depending on which rotation is present in a given wave it is called the wave's chirality or handedness. In general the polarization of an electromagnetic (EM) wave is a complex issue. For instance in a waveguide such as an optical fiber, or for radially polarized beams in free space, the description of the wave's polarization is more complicated, as the fields can have longitudinal as well as transverse components. Such EM waves are either TM or hybrid modes. For longitudinal waves such as sound waves in fluids, the direction of oscillation is by definition along the direction of travel, so there is no polarization. In a solid medium, however, sound waves can be transverse. In this case, the polarization is associated with the direction of the shear stress in the plane perpendicular to the propagation direction.
eBook - PDFQuantum Physics
Illusion or Reality?
- Alastair Rae(Author)
- 2012(Publication Date)
- Cambridge University Press(Publisher)
The Polarisation of light Imagine that a beam of light is coming towards us and that we think of it as an electromagnetic wave. As we saw in Chapter 1 (Figure 1.1) this means that at any point in space along the wave there is an electric field that is vibrating many times per second. At any moment in time, this electric field must be pointing in some direction, and it turns out that Maxwell’s equations require the direction of vibration always to be at right angles to the direction of travel of the light. So if the light is coming towards us the electric field may point to the left or the right or up or down or in some direction in between, but not towards or away from us (Figure 2.1). In many cases the plane containing the electric field direction changes rapidly from time to time, but it is possible to create light in which this plane remains constant. Such light is said to be plane polarised or sometimes just polarised. The plane containing the 17 18 Quantum physics: illusion or reality? Fig. 2.1 In a light wave coming towards us the electric field may oscillate vertically, horizontally or at some angle in between, but the oscillation is always perpendicular to the direction of travel of the light beam. electric field vectors is known as the plane of Polarisation and the direction in which the electric field points is known as the Polarisation direction. The idea of Polarisation may be more familiar to some readers in the context of radio or TV reception. To get a good signal into a receiver it is necessary to align the aerial dipole along the Polarisation direction (usually either horizontal or vertical) of the radio waves. This ensures that the electric field will drive a current along the aerial wire and hence into the set. Polarised light can be produced in a number of ways.
eBook - PDF- Md Nazoor Khan, Simanchala Panigrahi(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
4 Polarization 4.1 Introduction The phenomena of interference and diffraction proved successfully the wave character of light. However, it cannot confirm whether light is a transverse wave or a longitudinal wave. Interference and diffraction occur in transverse as well as longitudinal waves. The transverse nature of light was first confirmed by an optical phenomenon called polarization. Polarization is defined as a process of restricting the vibrations of a transverse wave to one direction or one plane only. 4.2 Polarization of Waves The appearance of a longitudinal wave is the same when viewed along any direction. It is perfectly symmetrical about the direction of propagation. However, this is not so with transverse waves. All electromagnetic waves are transverse waves. Light is an electromagnetic wave consisting of mutually perpendicular electric vector and magnetic vector. The electric vector is also called light vector. In case of transverse waves, the particles of the medium vibrate at right angles to the direction of propagation. If vibration of electric vectors of the light wave is confined to the XY plane, (i.e., the wave is plane polarized/linearly polarized with the plane of vibration along the XY plane) and the views taken along the X , Y , and Z direction will be different from each other. Ordinary light behaves in such a manner that it appears perfectly symmetrical about the direction of propagation, though there is no doubt about its transverse character – this is due to the fact that millions of light vectors undergo rapid changes in their direction within a metre length; not only does the direction of the transverse vibrations of the light wave change, but the character of the vibration also changes. The transverse vibration of the light wave may undergo changes from linear to circular, circular to elliptical. By using suitable devices, the light vector may be constrained
eBook - PDF- Charles A. Bennett(Author)
- 2022(Publication Date)
- Wiley(Publisher)
We will generally use the electric field to specify the complete electromag- netic wave. An electromagnetic wave with an electric field vector ⃗ E that oscillates back and forth along a fixed direction is said to be linearly polarized. In this case, the electric field oscillates within the plane of polarization, as shown in Figure 6.2. The plane of polarization for the wave illus- trated is inclined between the x–z and y–z planes. At any instant, the electric field vector has Principles of Physical Optics, Second Edition. Charles A. Bennett. © 2022 John Wiley & Sons, Inc. Published 2022 by John Wiley & Sons, Inc. 186 6 Polarization E B k λ Figure 6.1 A linearly polarized transverse electromagnetic wave. E (a) (b) E y E x x y k E x y z k Figure 6.2 (a) Linear polarization in the x–y plane. (b) The electric field vector may be resolved into components along the x and y axes. x and y components given by E 0x and E 0y . The corresponding forward traveling electromag- netic wave is determined by ⃗ E = ⃗ E 0 e i(kz−𝜔t+𝜑) = ( E 0x î + E 0y ̂ j ) e i(kz−𝜔t+𝜑) (6.1) where we have used the complex representation discussed in Section 1.6. Equation 6.1 repre- sents a linearly polarized electromagnetic wave traveling in the positive-z direction, as illus- trated in Figure 6.2. The initial phase angle 𝜙 represents the phase of the wave when z and t both equal zero. 6.2.1 Linear Polarizers A linear polarizer selectively removes light that is linearly polarized along a direction that is perpendicular to its transmission axis, as illustrated in Figure 6.3. In an ideal linear polar- izer, the transmission is zero for electric field components perpendicular to the transmission axis and 100% for electric field components parallel to the transmission axis. The light that is transmitted by the polarizer is linearly polarized along an axis that is parallel to the trans- mission axis, as shown.
eBook - ePubLiquid Crystal Displays
Fundamental Physics and Technology
- Robert H. Chen(Author)
- 2011(Publication Date)
- Wiley(Publisher)
4 The Polarization of an Electromagnetic WaveIn the previous chapters, the observation of double refraction of light and the polarizing effect of calcite were noted, and then light was shown to be an electromagnetic wave that when passed through a medium, was affected by the molecular structure of that medium. In the sinusoidal wave solutions to the electromagnetic wave equation, for anisotropic media, there was found a phase difference between the electric vector components of the light, and that caused a phase lag that polarized the light. The mathematical description of the polarization came from the Maxwell equations, but what does the polarization of light mean physically?Unpolarized LightNaturally occurring light is unpolarized, but according to solutions of the Maxwell equations given in Chapter 2, it was found that elliptical polarization is the state where there are no special correlations between the amplitudes and phases of the components of the electric vector; so what then is “unpolarized light”? The sum of the vibrations of the electric field components in natural light actually always form an ellipse (the most general form of polarization), but the polarization modes are constantly randomly changing through ellipses of different ellipticity (including lines and circles), and if the changes are more rapid than can be detected, then the light is considered unpolarized because all of the polarization effects are averaged out. In the words of Richard Feynman [1],light is unpolarized only if one is unable to determine whether it is polarized or not!Then practically, a beam of light can be tested for polarization by passing it through a polarizer, and if turning the polarizer does not change the intensity of the light passing through, it is deemed unpolarized
eBook - PDF- David Halliday, Robert Resnick, Kenneth S. Krane(Authors)
- 2019(Publication Date)
- Wiley(Publisher)
999 44-1 POLARIZATION OF ELECTROMAGNETIC WAVES You may have had the experience of rotating a small portable radio one way or another to improve the reception of the station to which you were listening. Or perhaps you adjusted the position or orientation of an antenna attached to your stereo system to increase the strength of the signal. If you have a TV antenna on your roof, you must align it in the proper orientation to receive the signals that are broad- cast from the station. These adjustments are necessary be- cause some types of antennas respond to the electric field of an electromagnetic wave, and a signal can be received only if the electric field of the wave can force electrons to flow along wires to make a current. The orientation of the antenna must be chosen to match the orientation of the field of the wave as it is produced by the broadcast antenna. For example, in the United States, television signals may be broadcast so that the field oscillates in a horizontal plane, so the plane of the rooftop antenna must also be horizontal (Fig. 44-1). In some other countries, TV signals may be broadcast with the field oscillating in a vertical plane, and so a different orientation of the rooftop antenna would be required to receive the signal. E B E B E B E B POLARIZATION I n Chapter 38, we showed electromagnetic waves trav- eling such that the electric field vector and magnetic field vector are perpendicular to each other and to the direction of propagation of the wave. That is, electromagnetic waves are transverse waves. This pre- diction follows from Maxwell’s equations. In many of the experiments we have described so far, light waves do not reveal their transverse nature. For example, reflection, refraction, interference, and diffraction can occur for longitudinal waves (such as sound) as well as for transverse waves.
eBook - PDFSneaking a Look at God's Cards
Unraveling the Mysteries of Quantum Mechanics - Revised Edition
- Giancarlo Ghirardi, Gerald Malsbary(Authors)
- 2021(Publication Date)
- Princeton University Press(Publisher)
2.1. Polarization States of the Electromagnetic Field In the preceding chapter we discussed states of the electric field that cor-respond to certain polarization states—that is, linear polarization. We saw how the electric field at one point of space varies with the progress of time (Figure 1.3), and how the same field varies at one given instant with the changes of position along the ray of the wave’s propagation (Fig-ure 1.4). It has been possible to use such simple graphs to represent the value and direction of the electric field because it has been tacitly as-sumed that we are dealing with linear polarization states. This means that the electric field (and the magnetic field perpendicular to it) oscillates in a plane. The same illustrations will also give us the opportunity of making more clear another topic we discussed in that chapter, namely, in-terference phenomena. Let us now suppose that at a certain instant of time, a certain region of space is traversed by two different “electromagnetic waves,” which for the sake of convenience we will now describe only in terms of the electric field. Let us then consider a light ray—a precise line along which the fields are being propagated—and suppose that the two waves are charac-C H A P T E R T W O 26 F IGURE 2.1. Constructive interference (a), and destructive interference (b), of two electrical fields with the same plane of polarization and of equal frequency and amplitude. The two fields are represented by the dotted and shaded lines, the resulting one by the solid dark line. As long as the fields are in phase (a), they give a field of double intensity (of quadruple energy density at every point). When their difference of phase is equal to half a wavelength (b), they will have (at every point and at every mo-ment) equal and opposite values, so that their sum will be equal to zero, and there will be no field. terized by electric fields polarized in the same plane, with equal wave-length and amplitude.
eBook - PDF- A Clarke, C Eberhardt(Authors)
- 2002(Publication Date)
- Woodhead Publishing(Publisher)
Furthermore, if the direction of rotation of the displacement in the x y plane is clockwise (when looking opposite to the direction of propagation), it is called right circularly-polarised. However, if the rotation is counter-clockwise and the phase difference is an odd multiple of 90º, it is called left circularly-polarised light. Circular Polarisation is illustrated in Fig. 1.14(c). 1.2.6 Polarisers and quarter-wave plates An important polarising element often found in microscopy is the linear polariser. In 1938, Edwin Land invented a special film (called Polaroid film) of oriented long-chain hydrocarbon molecules which became conducting when the film had been dipped in iodine solution (and he also invented the Polaroid film processing procedure). When the electric field vector is parallel to these chains, electric currents are set up along the chains and the light energy is absorbed. If the electric field is perpendicular to the chains, the light is transmitted with little attenuation. Such a film is called a polariser and the direction perpendicular to 22 Microscopy techniques for materials science the chains is called the transmission axis. Malus’ Law relates the output intensity, I , of the linearly polarised light wave to the initial intensity I 0 (when it passes through a polariser whose transmission axis is at an angle to the plane of Polarisation of the incident wave). I I 0 cos 2 1 : 24 The quarter-wave plate is a device for creating circular Polarisation from two linearly polarised beams. Some transparent crystals like calcite or mica are ‘doubly-refracting’ (or birefringent) because their refractive index has two different values for two different directions of Polarisation of an incoming light beam, as shown in Fig. 1.16(a). The quarter-wave plate is a specially cut crystal slab of thickness d , such that it has a slow axis (maximum index of refraction, n 1 ) at right angles to a fast axis (minimum index of refraction, n 2 ).
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
