Infrared light is a wavelength of energy that is invisible
to the human eye.
The most common source of this energy is heat;
objects can have their relative temperatures measured
by how much of this energy they give off.
Slightly more than half of the energy from the Sun
arrives on Earth in the form of infrared radiation. The
balance between absorbed and emitted infrared
radiation has a critical effect on Earth's climate.
Infrared is electromagnetic radiation with longer
wavelengths than those of visible light, extending
from the nominal red edge of the visible spectrum at
700 nanometers (nm) to 1 mm.
This range of wavelengths corresponds to a
frequency range of approximately 430 THz down to
300 GHz, and includes most of the thermal radiation
emitted by objects near room temperature
4. HOW INFRARED WORKS
infrared radiation is the region of the
electromagnetic spectrum between microwaves
and visible light.
In infrared communication an LED transmits the
infrared signal as bursts of non-visible light. At
the receiving end a photodiode or photoreceptor
detects and captures the light pulses, which are
then processed to retrieve the information they
Doctors use infrared lamps to treat skin diseases and relieve the pain of
infrared imaging is used extensively in military for target acquisition,
surveillance, wireless communication, night vision, homing and
infrared have allowed buildings to keep cool even in the summer. Gold
transparent films in the windows of large office buildings reflect
infrared and help to keep temperatures cool.
Photographers use film that is sensitive to infrared
rays to take pictures in places where there is no
TVs, VCRs and CD players also use infrared.
Infrared is used extensively in specially-designed
ovens for drying painted and enameled surfaces,
leather, metals, papers and textiles.
Low power requirements: therefore ideal for laptops, telephones,
personal digital assistants
Low circuitry costs: $2-$5 for the entire coding/decoding circuitry
Simple circuitry: no special or proprietary hardware is required,
can be incorporated into the integrated circuit of a product
Higher security: directionality of the beam helps ensure that data
isn't leaked or spilled to nearby devices as it's transmitted
Few international regulatory constraints: IrDA (Infrared Data
Association) functional devices will ideally be usable by
High noise immunity: not as likely to have interference from
signals from other devices
Line of sight: transmitters and receivers must be
almost directly aligned (i.e. able to see each
other) to communicate
Blocked by common materials: people, walls,
plants, etc. can block transmission
Short range: performance drops off with longer
Light, weather sensitive: direct sunlight, rain, fog,
dust, pollution can affect transmission
Speed: data rate transmission is lower than
typical wired transmission