Browse Definitions:
Definition

free-space optics (FSO)

Free-space optics (FSO), also called free-space photonics (FSP), refers to the transmission of modulated visible or infrared ( IR ) beams through the atmosphere to obtain broadband communications. Most frequently, laser beams are used, although non-lasing sources such as light-emitting diodes ( LED s) or IR-emitting diodes (IREDs) will serve the purpose.

The theory of FSO is essentially the same as that for fiber optic transmission. The difference is that the energy beam is collimated and sent through clear air or space from the source to the destination, rather than guided through an optical fiber. If the energy source does not produce a sufficiently parallel beam to travel the required distance, collimation can be done with lenses. At the source, the visible or IR energy is modulated with the data to be transmitted. At the destination, the beam is intercepted by a photodetector, the data is extracted from the visible or IR beam (demodulated), and the resulting signal is amplified and sent to the hardware.

FSO systems can function over distances of several kilometers. As long as there is a clear line of sight between the source and the destination, communication is theoretically possible. Even if there is no direct line of sight, strategically positioned mirrors can be used to reflect the energy. The beams can pass through glass windows with little or no attenuation (as long as the windows are kept clean!).

Although FSO systems can be a good solution for some broadband networking needs, there are limitations. Most significant is the fact that rain, dust, snow, fog, or smog can block the transmission path and shut down the network.

This was last updated in March 2011

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • security information and event management (SIEM)

    Security information and event management (SIEM) is an approach to security management that seeks to provide a holistic view of ...

  • polymorphic virus

    A polymorphic virus is a harmful, destructive or intrusive type of malware that can change or 'morph,' making it difficult to ...

  • cyberterrorism

    According to the U.S. Federal Bureau of Investigation, cyberterrorism is any 'premeditated, politically motivated attack against ...

SearchHealthIT

  • accountable care organization (ACO)

    An accountable care organization (ACO) is an association of hospitals, healthcare providers and insurers in which all parties ...

  • patient engagement

    Patient engagement is an ideal healthcare situation in which people are well-informed about -- and motivated to be involved -- in...

  • personal health record (PHR)

    A personal health record (PHR) is a collection of health-related information that is documented and maintained by the individual ...

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.

Close