There are many specifications used to define optical components, such as lenses, mirrors,
windows, etc. Some, like focal length, might seem obvious. Others, like power
and centration, might not be as self-explanatory.
Here is an incomplete glossary of some of the most commonly used specifications for
The world remains in a continuing state of uncertainty due to the new COVID-19 coronavirus. Face masks and disinfectants are selling very well. Disinfection with UV light could offer a way of disinfecting larger areas without the use of chemical disinfectants, especially in hospitals where patients are being treated.