Residual Light Amps
Even without light you can see the world with a residual light amplifier
A rest light amplifier is a tube with electrons that is able, under very dim light such as at night, to convert the intensity of the current available light into an optical system. In other words, you can, at night time, view the world around, so you can see what is happening around you.
Traditionally, rest light amplifiers are primarily used in military applications. Nowadays an increasing number of photographers who go out at night make use of a residual light amplifier.