Infrared is part of what is termed the "electromagnetic (EM) energy
spectrum", which includes x-rays, visible light, microwaves and
radio frequencies.
In the image below, you can see that infrared lies just under
visible light in its frequencies. Infrared energy has a longer wave
form than the energy of visible light.
Like radio
energy, there are many individual frequencies within the infrared
band of energy, and each "band" of frequencies has some unique
characteristics.
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Infrared energy is radiated heat energy. Heat is radiated in
the form of infrared energy. When you hold your hands to a
heater or a fire, what you are feeling as heat is actually
infrared energy. |
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When you turn on a light bulb, visible light is not the only thing it
produces, it is also producing other forms of energy like sound and heat
(infrared).
Every moment you
are alive, your body produces many different types of energy. Sound,
heat, radiant heat (Infrared, or IR), electricity, mechanical and
chemical, as well as performing an absolutely amazing range of chemical
reactions, some of them so quick that they can really only be expressed
mathematically.
Getting back to
thermal imaging, your body heat is radiated from you as IR (infrared)
energy. The scanning equipment captures this IR energy and quantifies
it. Because IR is radiated heat, an accurate temperature measurement can
be gained by careful measurement of the IR energy's amplitude and
frequency radiating from the emitting surface (skin).
In summary, thermal imaging is a picture that captures the infrared
energy (heat) emitted from your body instead of capturing the light
reflecting from your body.
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For a more detailed look at infrared and its history, please
visit
IPAC
for and excellent discussion of infrared energy including its
history, definitions and current uses.
N.B. - IPAC is an external and independent site. No affiliation
with ATI is suggested or implied.
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