Use of the polarizing filter to improve observations of the shadow edges on the refractometer
Darko B. Sturman and Duncan Parker FGA FCGmA

Proper use of the polarizing filter may greatly improve observation on the refractometer. Transmission of polarized light through a polarizing filter is described in detail and a simple construction is used to show how the strength of an image (for example, a shadow edge) depends on an angle between the vibration directions of the polarizing filter and the incoming polarized rays. Two examples are used to describe the incorrect use of the polarizing filter that may lead to wrong identifications.

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