The Physics of Night Vision Goggles

Physics is the branch of science when it comes to the nature and properties of matter and energy. The subject of physics includes everything that has to do with heat, mechanics, light, sound, electricity, the structure of atoms, magnetism and other radiation. A good example would be night vision goggles. Night vision goggles are a device with electronic eyes that magnify weak night vision into something more powerful. The light we can see is called visible light and is part of the electromagnetic spectrum.

There are other lights such as infrared and ultraviolet. The spectrum includes gamma rays, X-rays, UV, visible light, infrared, microwaves, and radio waves. Visible light consists of violet, indigo, blue, green, blue, yellow, orange, and red, which are sensitive to human eyes. Many people who work with the military and law enforcement use night vision technology. It can also be used to hunt and observe animals at night. Night vision goggles are green at night because photons hitting the lens at the front of the goggles carry light of all colors. It is better for people to watch a green screen at night than to watch a black and white screen.

There are two different types of night vision goggles: image enhancement (active) and thermal imaging (passive). There are five steps that explain how night vision goggles work.

First, the lens at the front is where the dim light comes in which is made up of photons of all colors. Photons are the particles of light.

Second, when photons enter the glasses, they hit a light-sensitive surface called a photocathode. The photocathode is a cathode that emits electrons when illuminated, causing an electric current. Electrons are subatomic particles that carry electricity around a circuit.

Third, the electrons are amplified by a photomultiplier which is a kind of photoelectric cell.

Fourth, after the electrons leave the photomultiplier, they hit a phosphor screen that is similar to an old-fashioned television.

Fifth, when there are more photons than originally entered the glasses, the screen becomes a brighter version than before. Thermography is all about a function of your temperature.

For example, the hotter a certain object is, the more radiation it emits. There are two different types of thermal imaging detectors which are the infrared camera with a cooled detector and the infrared camera with an uncooled detector. The difference between the two is only the temperature and whether or not it is stabilized.