Optical glasses will be found in scientific instruments, microscopes, fighter aircraft and most commonly in spectacles.
The most important properties are the refractive index and the dispersion:
- Refractive index is a measure of how much the glass bends light.
- Dispersion is a measure of the way the glass splits white light into the colours of the rainbow.
Glass makers use the variations in these characteristics to develop optical glasses.
In this Section
Many glass making terms have entered the language: 'Coddswallop': Hiram Codd invented the marble stoppered 'pop' bottle in the 1870s, and millions of the bottles were made, particularly in South Yorkshire. 'Wallop' was the name given to the cheap beer of the day, and beer drinkers dubbed the contents of the codd bottle 'a load of coddswallop'.