![]() The intensity of the transmitted light can be measured by a light detector connected to a voltmeter, scope, or PC. ![]() The idea is to measure the transmission of laser light through a linear polarizer as its transmission axis is rotated. Test gear can be set up to check the polarization state of a laser and define its polarization direction. If you look through both lenses separated by a small air gap, you will see that the amount of light transmitted can be varied by rotating one lens 90° with respect to the other. As an interesting experiment, remove the lenses from polarizing sunglasses that are being discarded. Modern polarizing filters are widely used, in everything from camera filters to inexpensive polarizing sunglasses. The longer microwave radiation is blocked while light passes through. (Today, polarizing filters are made by far cheaper, chemical means.) If you want to see an intersecting wire grid polarizer that blocks all radiation of a given wavelength, look at the glass door of your microwave oven. The separation of the wires must be less than the wavelength of the light to be affected, and the wires themselves must be still smaller. Light waves pass between the wires, but not through them. A wire-grid polarizer consists of fine metal wires in a plane. There are various ways to polarize light, the simplest being to pass it through a polarizing filter. Most electromagnetic radiation is called “incoherent”, meaning that it consists of random waves that have varying frequencies, phases and polarizations. ![]() Depending upon the direction of rotation, it may be right or left polarization as viewed from the source.Įlectromagnetic radiation is usually unpolarized or it may be said to exhibit random polarization when it comes from a lamp filament, fire, sun or most other natural or human-made sources. In elliptical polarization, the fields rotate at a constant rate. Light polarization may be linear or elliptical (of which circular polarization is a limiting case). An example of energy having transverse waves is light, which, as James Clerk Maxwell demonstrated in A Dynamical Theory of the Electromagnetic Field (1865), is a form of electromagnetic radiation. The oscillating motion is perpendicular to the direction of propagation, so this energy may exhibit polarization. In contrast, electromagnetic radiation is made up of transverse waves. The magneticįield vector B oscillates in a direction perpendicular to that of the electric field vector and to the direction of propagation of the wave. Because the physical motion of the oscillating particles is in the direction of wave propagation, this energy cannot exhibit polarization. Examples of longitudinal waves are sound waves in a gas or liquid such as human speech conveyed through air or cries of underwater whales in the ocean. Longitudinal waves are those in which the oscillations are in the direction of propagation. That is because polarization either as a process or a state applies only to transverse waves, not to longitudinal waves. Any treatment of wave polarization must begin with a discussion of the differences between transverse and longitudinal waves.
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