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Infrared Video: Infrared: More
than Your Eyes Can See
Introduction
The Sun gives off energy at a variety
of wavelengths. It emits x-rays, ultraviolet light, visible
light, infrared radiation, and radio waves. Most of the x-ray
and ultraviolet energy is absorbed by the atmosphere. However,
visible light from the Sun penetrates easily through the atmosphere.
Most eyes in nature respond to this range of wavelengths.
Our eyes are sensitive to the colors we know so well: blue,
green, yellow, orange, and red. These are the colors of light
emitted by the Sun and transmitted through our atmosphere.
Our eyes are only sensitive to a narrow range of wavelengths,
but we encounter “invisible” light in other ways.
Radar is used to find the locations of airplanes and doctors
use x-rays to diagnose diseases. If our ears had similar limitations
to our eyes, we could hear at best a few notes on a piano
around middle C but no other notes higher or lower.
What if our eyes responded to different wavelengths of light—perhaps
to a wavelength longer than the wavelength of red light? If
we had infrared vision, what would our world look like? Infrared
light is produced by every object that has a temperature above
absolute zero (-459.67 degrees F or –273.15 degrees Celsius).
This thermal radiation from every object gives us an indication
of its temperature.
When we look around the world with infrared vision, the world
looks very different. Hot objects stand out and look bright.
For example, a cat’s eyes and ears look bright while
its cold nose looks dark. Special infrared cameras with heat
sensitive detectors give us a very different view of a variety
of objects and animals.
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