Infrared

Type of EM wave of a particular wavelength just beyond what we can see on the red side of the spectrum.
→ William Herschel discovered this in 1800.
→ Infrared is all around us.
→ Most warm objects, including the human body, release radiation of this wavelength.
→ Heat-sensitive cameras work by detecting infrared radiation.
→ Half of the energy emitted by the Sun is infrared.

► Infrared scanners – used to know the temperature variation of the body.

► Infrared remote controls – used in TVs, video cassette recorders, and other electronic appliances.

► Some night vision goggles use IR.

► Some autofocus cameras have a transmitter that sends out infrared pulses.
  → The pulses are reflected by the object to be photographed back to the camera.
  → The distance of the object is calculated by the time lag between sending & receiving pulses.
  → The lens is driven by a built-in monitor to adjust the correct focus of the object.

HOW LASERS AND FIBER OPTICS HAVE IMPROVED TELECOMMUNICATION

• Lasers – Light Amplification by Stimulated Emission of Radiation.
  → Revolutionized communication and are largely responsible for the advent of the Information Age.

• Network of fiber optics – comprise the core of long-distance telephone communications and the internet.
  → Rely on transmitting through glass or plastic fibers via pulses of laser light.
  → Light pulses are converted to electrical signals that provide the information.
  → Rapidly replacing copper wire networks. Their flexibility, lower cost, higher efficiency, clearer signal, and increased capacity make them a superior option for the telecommunication industry.

• New types of lasers are expected to have a range of important applications (e.g., biomedical microscopy & analysis, quantum information processing).