Wave Optics - Polarising Agents

Description:

The substance that has the ability to polarise the light is known as polarising agent. There are different polarising agents, some of which are present in nature while others are manmade polarising agent.

Tourmaline Crystal

It is a natural polarizing agent. This is the most commonly used polarizing agent. It is used in the Malu’s law of polarization.

Nicole Prism

It is a man-made polarizing agent. It is constructed by joining two calcite crystals with a specific angular measurements of 22⁰ - 68⁰ - 90⁰. These crystals are joined together using an adhesive called Canada Balsam which have a refractive index 1.55. The Nicole prism generates two rays which are Extra-ordinary ray (E-ray) and Ordinary ray (O-ray).

E-ray bends less than the O-ray. Nicole prism is mostly used in laboratories.

Herapath Crystal

This polarizing agent was constructed by a scientist named Hearpath in the year 1852. This crystal was Iodo-sulphate of quinine but this was not a stable substance and used to decompose itself.

Polaride

In 1934, a scientist named Lamb used Herapath crystal, he made them stable and put them inline on a transparent paper, so that the crystals acted as a polarizing agent, this was called polaride.