This is above the objective, and is made up of a polarising plate, whose height may be adjusted at will, using a graduated dial (1).

Unlike the polariser, the analyser does not always have a part to play in the passage of the light rays and can be installed or removed at will. It is used to study certain properties but is not necesary for others.

The polarising plane is generally N-S, and it is always perpendicular to the polariser, such that if there is no object in the way, no light passes and Extinction occurs.

Below it is a slot where compensating plates can be inserted.

When only the polariser (1) is being used, a normal image is observed, but when the analyser is in place (2), an extinction of light occurs.

If an anisotropic substance is in the light's path, the light splits into two rays which vibrate perpendicularly and do not necessarily coincide with the directions of the polariser or analyser. When these rays reach the analyser, two components come into being which vibrate, one on the plane of the analyser and the other on a perpendicular one. The former is responsible for the grain being seen, whilst the latter is annulled. A false colour appears, known as an interference colour (3).


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