An OTDR, rather than being a parameter in itself, is a piece of equipment used to measure Attenuation along the length of the fiber. Attenuation in an optical fiber occurs as a result of the way the light interacts with the structure of the fiber both at a microscopic and a macroscopic level. It is one of the parameters that can significantly be affected by the processes used to manufacture and install/join the cable.
All the intrinsic and extrinsic mechanisms that create this loss of signal are known to be wavelength dependent and as such are normally measured over the useable spectrum for which the fiber is designed('Spectral Attenuation'), but with an OTDR, these Attenuation characteristics are measured as a function of length rather than wavelength. Having said that, OTDRs do posses the ability to carry out this test at more than one wavelength.
There are several mechanisms to be considered:
- Scattering and Absorption (the intrinsic attenuation of the fiber)
- Splicing/Connectorising (extrinsic single point events)
- Bending (extrinsic single and macro events)
The OTDR enables the user to determine the effects of these mechanisms individually. The main purposes of this measurement is to yield information about the location of any undesirable or out of spec attenuation events.
The 'Production/Lab/R&D' range is suitable for manufacturers of fiber and cables.
The 'Field Equipment' range is suitable for measuring installed links in the field as well as in the cable manufacturing environment.