Polarization
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Polarization as PDF for free.
More details
- Words: 313
- Pages: 2
Card # 55 Polarization: The lack of asymmetry of vibration about the direction of propagation of light is called a polarization.
Unpolarized light:
The light having vibrations of electric field vectors in all possible directions perpendicular to direction of propagation of wave are called unpolarized light. Plane polarized light:
The light having vibrations of electric field vectors only in one direction perpendicular to direction of propagation of wave is called polarized light. Polaroids:
These are thin films of ultramicroscopic crystals of quinine idosulphate with their optical axis parallel to each other. Polaroid allows the light oscillations parallel to the transmission axis pass through them. If unpolarized light is incident on a Polaroid, the transmitted light is plane polarized as shown in fig. Here the vertical oscillations are transmitter because the transmission axis is also vertical. Horizontal oscillations are not transmitted. That is why, on the right hand side there are no dots at the intersection of lines. The crystal or Polaroid on which unpolarized light is incident is called polarizer. Crystal on which polarized light is incident is called analyzer. If the transmission axis of polarizer & analyzer are parallel, then the whole polarized light passes through the analyzer. If they are perpendicular to each other then no light passes through analyzer. Such polarizer & analyzer are said to be crossed.
Polarization by Reflection: Brewster’s law: If unpolarized light falls on a transparent surface of refractive index n at certain angle, then light is Plane polarized. Under this condition (Brewster’s law) n = tan ip and the reflected refracted rays are mutually perpendicular i.e. ip + r = 90˚ where r is the angle of refraction.
Malus law: If I0 be the intensity of the polarized light incident on the analyzer and θ is the angle between the analyzer & transmission axis of polarizer, then the intensity is given by I = I0cos2θ
Unpolarized light:
The light having vibrations of electric field vectors in all possible directions perpendicular to direction of propagation of wave are called unpolarized light. Plane polarized light:
The light having vibrations of electric field vectors only in one direction perpendicular to direction of propagation of wave is called polarized light. Polaroids:
These are thin films of ultramicroscopic crystals of quinine idosulphate with their optical axis parallel to each other. Polaroid allows the light oscillations parallel to the transmission axis pass through them. If unpolarized light is incident on a Polaroid, the transmitted light is plane polarized as shown in fig. Here the vertical oscillations are transmitter because the transmission axis is also vertical. Horizontal oscillations are not transmitted. That is why, on the right hand side there are no dots at the intersection of lines. The crystal or Polaroid on which unpolarized light is incident is called polarizer. Crystal on which polarized light is incident is called analyzer. If the transmission axis of polarizer & analyzer are parallel, then the whole polarized light passes through the analyzer. If they are perpendicular to each other then no light passes through analyzer. Such polarizer & analyzer are said to be crossed.
Polarization by Reflection: Brewster’s law: If unpolarized light falls on a transparent surface of refractive index n at certain angle, then light is Plane polarized. Under this condition (Brewster’s law) n = tan ip and the reflected refracted rays are mutually perpendicular i.e. ip + r = 90˚ where r is the angle of refraction.
Malus law: If I0 be the intensity of the polarized light incident on the analyzer and θ is the angle between the analyzer & transmission axis of polarizer, then the intensity is given by I = I0cos2θ
Related Documents
Polarization
December 2019 5
Polarization
October 2019 14
Classification Of Polarization
December 2019 8
Polarization Controller Stanford Lefevre
April 2020 3
