Analysis of polarized light, refraction, polarizers

1809 brought about changes in the scientific world society. Engineer from France, E. Malus discovered a new method of polarization of the light. Experimenting, he accidentally drew attention to the fact that if the crystal can rotate reflected from the glass beam, the intensity of light may either increase or decrease. But all the light is not extinguished, but only increases or diminishes, but only at a certain position of the crystal. The statement called “law of Malus”, it was recognized in the scientific community.

We know From physics that light can be converted into a plane polarized beam. This happens when using special devices that can pass only a certain direction of oscillation. An example of this can be located parallel to the plane of oscillations, transmits light and, perpendicular to check fluctuations. As the polarizer used in the anisotropic medium with respect to the variations of the vector, such as crystals. The most famous natural origin is tourmaline. He is strong enough to absorb the rays of light whose electric vector perpendicular to the optic axis, which also follows as a conclusion of the law of Malus. But the light in which this element is a parallel, almost not absorbed. This explains the fact that natural light passing through the crystal plate, and is absorbed only half of the linearly polarized with the electric vector are parallel to the optic axis of tourmaline.

More convenient to use a crystal having the same characteristics, is Polaroid. It consists of artificially prepared colloidal films, which are needed in order to obtain polarized light. As with tourmaline, the principle of operation is based on a single crystal, which absorbs vibrations perpendicular to the light. And in this phenomenon the law of Malus is not expressed. Consider other examples.

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But when the polarization of the light rays occurs when the refraction or the reflection at the boundary with isotropic dielectric – this is the law of Malus. He corrected the number of physical phenomena associated with the electric oscillations of light.

But the law of Malus, the conclusion of which we formulated above, does not claim that this method of polarization the main and only. There are others.

Any device that is used to obtain the polar rays of light is called a polarizer. But studied and studied it with the help of analyzer.

For Example, there are two crystals, which are arranged one behind the other so that the axes form an angle. The first will miss the light, whose electric vector is directed parallel to its axis. Component of the intensity of the beam is delayed by the second crystal. And in two of the Polaroid it will pass with the same length of the electric vectors. In other words, the ratio of these intensities will be proportional to the square of the amplitude.

We conclude that the light passing through the analyzer, its power is equal to the force of the beam travelling through the polarizer and multiplied by the cosine of the angle squared between them. This ratio is the phenomenon that describes the law of Malus.

This also can be attributed to the double refraction of rays of light, which is the main feature when passing through crystals. This is due to the features that are present in the environment anisotropy to the light propagation. For example, sending a crystal spar, a narrow light beam passing through it, there will be two separated beam running parallel to each other. This will happen in any case, even if the light falls on the crystal in the normal position. One of them is called common and is a continuation of the primary beam, and the second – extraordinary, as has the ability to reject.