Physics is the branch of science when it comes to the nature and properties of matter and energy. The matter of physics includes anything having 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 goggle is a device with electronic eyes that boost weak night-time vision into something more powerful. The light we can see is called visible light which is part of the electromagnetic spectrum.
There are other lights such as infrared and ultraviolet. The spectrum includes the gamma rays, x-rays, UV, visible light, infrared, microwave, and radio waves. Visible light consists of violet, indigo, blue, green, blue, yellow, orange, and red which are sensitive to the human eyes. Many people who works with the military and law enforcement agencies use night vision technology. It can also be used for hunting and watching animals during the night. The night vision goggles are green at night because the photons that hit the lens at the front of the goggles are carrying light of all colors. It is better for people to look at a green screen at night than looking at a black and white screen.
There are two different types of night vision goggles are image enhancement (active) and thermal imaging (passive). There are five steps explaining the way night vision goggles work is.
First, the lens at the front is where the dim light enters which is made out of photons of all colors. Photons are the particles of light.
Second, when the photons enter the goggles, it strikes a light-sensitive surface called a photocathode. 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 some kind of photoelectric cell.
Fourth, after the electrons leave the photomultiplier, it hits a phosphor screen which is similar to the old fashion television.
Fifth, when there are more photons than originally entered the goggles, the screen becomes a brighter version than before. Thermal imaging is all about a function of their 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 cooled detector infrared camera and uncooled detector infrared camera. The difference between the two is only the temperature and is it stabilized or not stabilized.
Source by Tierra T Smith