LCD

Liquid crystals are a class of materials that change their transmission/reflection characteristics in response to an electric field.

Examples:

1 The light reflected from black and silver LCD calculator screens is polarized. Reflection occurs only from the parts of the screen that appear silver.

2 LCD computer screens, telephone displays etc. in full color are a more advanced application. Again the light from the screen is polarized.

LCD telephone screen and Polaroid film. Rotating the Polaroid 90° obscures the screen.

Details are on the web.