Discovery of Infrared
In 1800, William Herschel conducted an experiment measuring the difference in temperature between the colors in the visible spectrum.
Infrared is a section of invisible light on the electromagnetic spectrum. It’s a form of radiant heat that can also be called “infrared energy.” About 80% of the sun’s rays actually fall in this part of the spectrum.
Night-vision goggles or infrared cameras–allow us to “see” the infrared waves emitting from warm objects such as humans and animals.
Many objects in the universe are too cool and faint to be detected in visible light but can be detected in the infrared.
When sun rays reach the object, they heat it from the inside leaving it warm without heating the air around it.IR travel through the atmosphere without the need of air or any other medium
In communication system
Infrared (IR) is a wireless mobile technology used for device communication over short ranges.Wireless Infrared (IR) communications system is meant to use free-space propagation of light waves as a transmission medium in IR radiation. It is basically light that cannot be seen. An infrared Light Emitting Diode (LED) is to emit the light and a photo diode is equipment to receive the light.
Why infrared wireless
Infrared emitters and detectors capable of high speed operation are available at low cost.
The infrared spectral region offers a virtually unlimited bandwidth.
No bandwidth regulation.
IR makes it easy to secure transmissions and it prevents interference between links operating in different rooms.
Communication is usually exchanged on a one-to-one basis. Thus, data transmitted between devices is normally unencrypted.
IR communication has major limitations because
It requires line-of-sight.
Unable to penetrate walls and serve as short-range communication solutions. Communication from one room to another requires the installation of infrared access points that are interconnected via a wired backbone.
In many indoor environments there exists intense ambient infrared noise, arising from sunlight, incandescent lighting and fluorescent lighting, which induces noise in an infrared receiver.
IR enabled devices are known as IrDA devices because they follow the standards set by the Infrared Data Association (IrDA).
Radio and Infrared Communication
Radio and infrared are transmission media.
Radio is favored in applications where user mobility required.
Radio is favoured when transmission through walls or over long ranges is required.
Infrared is favored for short-range applications.
IR is favoured for low cost installation.
IR is favoured when per-link bit rate must be maximized.
IR is favoured when international compatibility is required.
IR is favored when no license required.