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How does night vision work?
Home » Gadgets » Night Vision » How does night vision work?The first step in learning how to see in the dark, is actually learning more about light. The amount of energy in a light wave is related to its wavelength: Shorter wavelengths have higher energy. Of all visible light, violet has the most energy, red has the least, (think ROY G BIV). Just next to the visible light spectrum is the infrared spectrum.
Infrared light can be split into three categories:
• Near-infrared (near-IR) - Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.
• Mid-infrared (mid-IR) - Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.
• Thermal-infrared (thermal-IR) - Occupy the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.
The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level.
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