In telecommunications, Free Space Optics (FSO) is an optical communication technology that uses light propagating in free space to transmit data between two points. The technology is useful where the physical connection by the means of fibre optic cables is impractical, due to high costs or other considerations. Free Space Optics are also used for communications between spacecrafts. The optical links are implemented using infrared laser light, although low-data-rate communication over short distances is possible using LEDs. Maximum range for terrestrial links is in the order of 10 km , but the stability and quality of the link is highly dependent on atmospheric factors such as rain, fog, dust and heat. In space range is in the order of several thousand kilometers . IrDA is a very simple form of free-space optical communications.
The invention of laser in the 1960s, revolutionized free space optics. Military organizations were particularly interested and boosted development. The technology lost market momentum when the installation of optical fiber networks for civilian uses was at its peak.
Typically scenarios for use are:
The light beam can be very narrow, which makes FSO hard to intercept, improving security. In any case, it is comparatively easy to encrypt any data traveling across the FSO connection for additional security. FSO provides vastly improved EMI behavior using light instead of microwaves.
These factors cause an attenuated receiver signal and lead to higher bit error ratio (BER). To overcome these issues, vendors found some solutions, like multi-beam or multi-path architectures, which use more than one sender and more than one receiver. Some state-of-the-art devices also have larger fade margin (extra power, reserved for rain, smog, fog). To keep an eye-safe environment, good FSO systems have a limited laser power density and support laser classes 1 or 1M. Atmospheric and fog attenuation, which are exponential in nature, limit practical range of FSO devices to several kilometres.
US Patent Issued to Fuji Xerox on Oct. 19 for "Vertical-Cavity Surface-Emitting Laser, Module, Optical Transmission Device, Optical Transmission System, Free Space Optical Communication Device, and Free Space Optical Communication System" (Japanese Inventors)
Oct 20, 2010; ALEXANDRIA, Va., Oct. 26 -- United States Patent no. 7,817,703, issued on Oct. 19, was assigned to Fuji Xerox Co. Ltd. (Tokyo)....
WIPO ASSIGNS PATENT FOR "METHOD AND SYSTEM FOR FREE-SPACE OPTICAL COMMUNICATION WITH REDUCED SCINTILLATIONS" (RUSSIAN INVENTOR)
Aug 20, 2011; GENEVA, Aug. 20 -- Publication No. WO/2011/098982 was published on Aug. 18. Title of the invention: "METHOD AND SYSTEM FOR...