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Fiber Optic Cable and Connector Selection - page 5 / 5





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A stabilized sight source (SLS), an optical power meter (OPM) and an optical return loss meter (ORLM) are required to determine the performance of cables. Insertion loss measurements are performed with an SLS and an OPM. Return loss is measured with an SLS and an ORLM. The SLS should be the same wavelength as the system because connector and cable performance can vary dramatically with wavelength. For locating faults in cables, an optical time domain reflectometer (OTDR) is required.

More elaborate tests can be run on systems to look for specific problem areas. These tests are usually driven by the environment, such as performing drop-out testing on aircraft connectors to determine if a connection is temporarily broken during vibration.

11. System Qualification

For critical applications, such as in aircraft, qualification testing is required to determine if a fiber optic system will perform properly. Most connectors and cables have been qualified to meet certain environmental requirements but this does not mean they meet all environmental requirements. System designers must examine what environment a connector is qualified to and with what cable. Different cables on the same connector act differently when subject to vibration or thermal cycling.

Most qualification testing is well-defined in Bellcore and military standards and can be performed in a relatively short time. The one test that can take a long time is thermal life testing, which is required for systems that will go through thermal cycles and must work for long periods of time without failure.


Fiber optic systems have performed flawlessly in environments as diverse as the bottom of the ocean and in space. The key to designing a successful fiber optic system is understanding the performance and environmental requirements, implementing good designs utilizing the appropriate components, properly testing the system to verify requirements compliance, and using validated installation configurations and methodologies to assure system integrity and longevity.

ANDREW DEVINE is President of Coastal Connections, 2368 Eastman Ave., Ventura, CA 93003; (805) 644- 5051 Fax: (805) 644-5355; E-mail: andy@coastalcon.com; Web site: www.coastalcon.com. RON DEPPEN was business unit leader, Mil/Aero, RIFOCS Corp.


End Applications: High-reliability applications such as communications, aerospace, automotive and marine systems

Related Products: Fiber optic cables and connectors

Main Point: These 11 steps provide readers with the knowledge to know what questions to ask and what tradeoffs are being made when designing a fiber optic system.

The keys to designing a successful system are:

  • Understanding the performance and environmental requirements

  • Implementing good designs utilizing the appropriate components

  • Properly testing the system to verify requirements compliance

  • Using validated installation configurations and methodologies to assure system integrity and


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