(optics) A point from which light (or other radiation) apparently emanates, such as in the virtual image produced by a plane mirror.

A very intense focus (of the human mind); a hyperfocus.

(programming, information science) Text normalization where uppercase and lowercase characters are treated as equivalent.

(botany) Synonym of leaf trace

plural of foliar trace

(rail transport, UK) A small explosive charge (detonator) which can be placed on a railway line in fog, to be detonated by a train passing over it as a warning signal to the driver.

plural of fog signal

An mirror used to bend an optical path so that it can be made longer than the physical size of the system

A fold mirror that is a "sphere", i.e. a spherical mirror

A fold mirror that is a "flat", i.e. a plane mirror