The U.S. Border At Night, Part 6

IR Night Vision cameras

IR Night Vision cameras are simply daylight or low light level cameras that have been fitted with some kind of light source that the human eye does not see. These cameras can be used in the daytime and at night (using their built in light source).

Humans can see a full range of colors and those colors really represent the wavelength of the light being seen. Light at a higher, or lower, wavelength than we can see can be used by a camera sensitive to that wavelength of light. The camera can see you, but you cannot see that it is seeing you.

Most of the IR cameras use lower wavelength light — called Infra-red or IR. These cameras have a huge light bulb with a special filter which allows only invisible to us IR light through the filter. Other brands use hundreds of small semiconductor illuminators in a huge flat panel — LEDs. With a bright enough IR light source these cameras can see for several miles.

These cameras cannot see through fog or rain or snow or a sand storm or even haze. They cannot see any better than you can with your own eyes — if you could see IR. This can be very bad if there is fog or rain or snow or a sand storm or haze and gang members or drug smugglers are coming across the border and your job is to see them.

Again, the cameras can see objects through the obscurant if enough light gets through the obscurant. For example, they — just as you — can see brake lights of a distant car right through the fog.