Instead, they allow light from a very dimly lit location to pass into the goggles, which converts that light into an electrical signal using a special surface called a photocathode.
The next evolution of the technology involved a more advanced photocathode that could further improve the amplification of light.
The photocathode converts the few photons that strike it into a corresponding pattern of electrical energy called electrons.
Any available light from the outside world enters the lens and strikes a special device called a photocathode.
Electrons from the photocathode are then amplified and projected onto a screen inside the goggles.