The classical meaning of the word "glass" is extended in this Standard to cover "organic glass" and some crystalline optical materials.
Glasses,
inorganic as well as organic, appear as optical elements: e.g. windows, lenses, prisms, solar-cell covers and filters.
Optical materials can be grouped as:
-inorganic glasses - such as silicates, alumino-silicates and boro-silicates;
-organic "glasses" - polymers based on acrylic and methacrylic polymers, poly-carbonate and some polystyrene grades;
-crystalline optical materials - pure silica, sapphire and transparent fluorides. |
