Low-light imaging is a technology used to improve visibility in dimly lit environments. Low-light imaging, thermal imaging and near-infrared illuminations are the three most commonly used night vision technologies.
The most common method of low-light imaging uses a device called an image intensifier to amplify available light. Here's a brief explanation of how an image intensifier works:
- Available light is focused through the objective lens (the lens closest to the object being viewed) onto the photocathode (a photosensitive surface that emits electrons in response to light or other radiant energy) of the image intensifier.
- Electrons released by the cathode are accelerated by an electric field.
- The accelerated electrons enter holes in a microchannel plate and bounce off specially-coated internal walls which generate more electrons as they bounce through.
- This activity creates a denser “cloud” of electrons representing an intensified version of the original image.
- The electrons hit a phosphor screen, making the phosphor glow.
- The light displays the desired view to the user or to an attached camera or video device.
See also: photon, photonics