The concept of light must be understood in order to comprehend the concept of night vision. A light wave's energy is inversely proportional to its wavelength; the higher the energy, the shorter the wavelength. The energy of visible light is divided into red and violet, with violet having the highest and red having the lowest. The infrared spectrum is located next to the visible light spectrum. There are several categories for infrared:
Near infrared (near R)—Near infrared has a wavelength range of 0.7–1.3 microns and is a form of light that is close to visible light (1 micron is equal to one ten thousandth of a meter).
Mid-Infrared (Mid-IR) - The mid-infrared has a wavelength range of 1.3 to 3 microns. Many electrical devices, including remote controls, utilise near-infrared and mid-infrared technology.
Thermal Infrared (Thermal IR): With a wavelength range of 3–30 microns, thermal infrared makes up the majority of the infrared spectrum. Because thermal infrared is emitted by objects rather than reflected by them, it differs significantly from the other two forms of infrared. A change in an object's atoms causes it to produce infrared light.
