Polarimeter passes polarized light through an optically active substance to measure the angle of rotation. This polarized light will rotate either clockwise or anti-clockwise when it passes through chemical substances that are optically active. This amount of light rotating is known as angle of rotation. If the light rotates to left (anti-clockwise) it is a levo-isomer, and if it rotate to right (clockwise) it is a dextro-isomer. A few different types of Polarimeters include:
Laurent's Half-Shade Polarimeter
Biquartz Polarimeter
Lippich Polarimeter
Manual Polarimeter
Fully Automatic Polarimeter
Each polarimeter is used according to its usages in different industries.