What are the applications of glass?
The term 'glass' refers to a state of matter, usually produced when a viscous molten material is cooled rapidly to below its glass transition temperature, with insufficient time for a regular crystal lattice to form. Consequently a key feature is that glasses have structures that are liquid-like i.e. not crystalline; this means that they lack the internal structural boundaries present in most other materials. So they are typically transparent to light, although this can also depend on their composition. As a result they are enormously valuable for windows, containers, ovenware, tableware, lighting, and optical fibres for telecommunications (underpinning the internet and mobile phones).
A wide range of additional glass applications result from glasses that have been treated to give them added value (functional glasses). Such glasses typically possess surface properties different from the bulk ones due to chemical or thermal treatment, coatings or surface structuring. The Romans for example were able to produce beautiful artistic effects using technically challenging surface modification.
These days techniques such as laser structuring are able to modify a glass surface on an amazingly fine scale. This picture, for example, shows a planar diffractive microlens with a diameter of just 0.6 mm .