Subscribe to FOSA News

FOSA DFOS Glossary

DFOS Glossary

To download the glossary app on an Android device click here
A
Acoustic Bandwidth [DAS] - The range of frequencies over which the fiber optic sensor, usually DAS, measures over. The bandwidth can be described by maximum detectable frequency to minimum detectable frequency.

Asset [generic] - The physical object to be monitored using fiber optic sensors. The asset is considered to be separate from the optical fiber and therefore a mapping is usually required from fiber to the asset.
Examples: Pipelines, Power Cables, Tunnels.

B
Brillouin Frequency [DSS] - Frequency shift of light caused by Brillouin scattering.

Brillouin Scattering [DSS] - Inelastic scattering of light involving energy transfer to or from acoustic phonons.

C
Cycle time [generic] - Time for measuring a complete sequence of channels where multiple fiber channels are available on the instrument.

Channel [DAS] - Range of adjacent fiber locations used for evaluating acoustic signals.

D
DAS [DAS] - Distributed Acoustic Sensing is a sensing technology that delivers real time spatially resolved acoustic and vibration output from virtually unlimited points along a fiber optic cable. The technology effectively turns common optical fiber (or specially optimized cables) into a series of thousands of sensitive virtual microphones or vibration sensing devices. DAS produces thousands of channels of acoustic output from these virtual microphones - in real time. See FOSA Technology Primer What is Distributed Acoustic Sensing? FOSA Introduction to Distributed Acoustic Sensing

DFOS [DAS, DSS, DSTS, DTS] - Distributed fiber optic sensors are systems that connect opto-electronic interrogators to an optical fiber (or cable), converting the fiber to an array of distributed sensors. The fiber becomes the sensor while the interrogator injects laser energy into the fiber and detects events along the fiber. See FOSA Technology Primer What is Distributed Fiber Optic Sensing? FOSA Introduction to Fiber Optic Sensing

Distance Range [generic] - Maximum length of optical fiber to be measured.

Distributed Acoustic Sensor [DAS] - Distributed Acoustic Sensing (DAS) is a sensing technology that delivers real time spatially resolved acoustic and vibration output from virtually unlimited points along a fiber optic cable. The technology effectively turns common optical fiber (or specially optimized cables) into a series of thousands of sensitive virtual microphones or vibration sensing devices. DAS produces thousands of channels of acoustic output from these virtual microphones – in real time. See FOSA Technology Primer What is Distributed Acoustic Sensing? FOSA Introduction to Distributed Acoustic Sensing

Distributed Fiber Optic Sensor [DAS, DSS, DSTS, DTS] - Distributed fiber optic sensors (DFOS) are systems that connect opto-electronic interrogators to an optical fiber (or cable), converting the fiber to an array of distributed sensors. The fiber becomes the sensor while the interrogator injects laser energy into the fiber and detects events along the fiber. See FOSA Technology Primer What is Distributed Fiber Optic Sensing? FOSA Introduction to Fiber Optic Sensing

Distributed Strain Sensor [DSS] - Distributed Strain Sensing (DSS) is a fiber-optic sensing technology providing spatially resolved elongation profiles along a fiber-optic sensing cable. By combining multiple sensing cables at different positions in the asset cross-section, DSS is used to compute the asset (device under test) elongation (strain), shape (bending radius and bending direction), twist etc. See FOSA Technology Primer What is Distributed Strain Sensing? FOSA Introduction to Distributed Strain Sensing

Distributed Strain and Temperature Sensor [DSS] - Distributed Strain and Temperature Sensing (DSTS, also known as DTSS) is a fiber optic sensing technology that delivers spatially resolved measurements of changes to both strain and temperature at any point along the length of a fiber optic cable. This allows a single optical fiber to replace thousands of individual strain or temperature sensors. See FOSA Technology Primer What is Distributed Strain and Temperature Sensing? FOSA Introduction to DSTS

Distributed Temperature Sensor [DTS] - Distributed Temperature Sensing (DTS) is a fiber-optic sensing technology for measuring spatially resolved temperature profiles along fiber-optic sensor cables. Sensor cables may be installed near linear assets as well as on 2- or 3-dimensional objects for measuring their temperature profiles. See FOSA Technology Primer What is Distributed Temperature Sensing? FOSA Introduction to Distributed Temperature Sensing

DSS [DSS] - Distributed Strain Sensing is a fiber-optic sensing technology providing spatially resolved elongation profiles along a fiber-optic sensing cable. By combining multiple sensing cables at different positions in the asset cross-section, DSS is used to compute the asset (device under test) elongation (strain), shape (bending radius and bending direction), twist etc. See FOSA Technology Primer What is Distributed Strain Sensing? FOSA Introduction to Distributed Strain Sensing  

DSTS, also known as DTSS [DSS] - Distributed Strain and Temperature Sensing is a fiber optic sensing technology that delivers spatially resolved measurements of changes to both strain and temperature at any point along the length of a fiber optic cable. This allows a single optical fiber to replace thousands of individual strain or temperature sensors. See FOSA Technology Primer What is Distributed Strain and Temperature Sensing? FOSA Introduction to DSTS

DTS [DTS] - Distributed Temperature Sensing is a fiber-optic sensing technology for measuring spatially resolved temperature profiles along fiber-optic sensor cables. Sensor cables may be installed near linear assets as well as on 2- or 3-dimensional objects for measuring their temperature profiles. See FOSA Technology Primer What is Distributed Temperature Sensing? FOSA Introduction to Distributed Temperature Sensing  

DTSS, also known as DSTS [DSS] - Distributed Temperature and Strain Sensing is a fiber optic sensing technology that delivers spatially resolved measurements of changes to both strain and temperature at any point along the length of a fiber optic cable. This allows a single optical fiber to replace thousands of individual strain or temperature sensors. See FOSA Technology Primer What is Distributed Strain and Temperature Sensing? FOSA Introduction to DSTS

F
Fiber channel [generic] - Length of fiber connected to one optical output of an interrogator.

G
Gauge Length [DAS] - Length of a fiber section used to evaluate changes of length or phase.

I
Interrogation Rate [DAS, DTS, DSS] - See Pulse Repetition Frequency.

M
Measurement time [generic] - Time required for taking a measurement from one fiber.

O
Optical Loss Budget [generic] - The optical loss budget establishes the total amount of tolerable loss attributable to the fiber/cable loss and loss through connectors and splices.

P
Pigtail [generic] - A pigtail is a short optical fiber cable with an optical connector on one end and a length of exposed optical fiber at the other end.

Pulse Rate, also known as Pulse Repetition Rate [generic] - Number of laser pulses per second.

Pulse Repetition Rate, also known as Pulse Rate [generic] - Number of laser pulses per second.

R
Raman Scattering [DTS] - Inelastic scattering of light involving energy transfer to or from optical phonons or molecular vibrations.

Rayleigh Scattering [DAS] - Elastic scattering of light at particles or inhomogeneities that are smaller than its wavelength.

S
Single Ended Measurement - A measurement taken from only one end of an optical fiber. Example: measurements on a subsea power cable where access to the subsea end of the fiber is not possible.

Sampling Interval [generic] - Distance between measuring data locations along a fiber. 

Spatial Resolution [DTS, DSS] - Length of a temperature or strain event required for 90% reading response.

T
Temperature Resolution - Standard deviation of local temperature data taken in a measuring sequence.

Temperature Accuracy [DTS] - Deviation between average measured temperature and true temperature.

W
Warmup Time - Time between power-on and readiness to take measurements according to the specification.

Z
Zone [generic] - Range of adjacent fiber locations used for triggering events according to common alarm criteria.

FOSA thanks the efforts of the FOSA Technology Committee for creation of the FOSA DFOS Glossary, in particular member companies AP Sensing, NKT Photonics, Omnisens and OptaSense.

2020 Copyright ©Fiber Optic Sensing Association. All rights reserved.