GB/T 43256-2023Test method for parameters of distributed optical fibre strain measuring system (English PDF)

3.1 Optical fibre strain

The relative change is used to characterize the degree of change in fiber length caused by axial tension or compression of the optical fiber.

Note 1. The amount of strain is the ratio of the amount of axial deformation to the original length. When an optical fiber is stretched or compressed, positive or negative strain occurs respectively.

Note 2. Optical fiber strain is dimensionless and is generally expressed by epsilon or µepsilon or %. 1µepsilon represents the change of 1 x 10^-6, 1epsilon=1000000µepsilon, and 1% strain value is equivalent at 10000µepsilon.

3.2 Distributed optical fibre strain measuring system

A test instrument or test system for testing the spatial distribution of optical fiber strain.

Note 1. Includes two types. single-ended distributed optical fiber strain testing system and loop-type distributed optical fiber strain testing system.

Note 2. The types of optical fibers tested include single-mode optical fiber, multi-mode optical fiber, polarization-maintaining optical fiber, etc.

3.3 Single-ended distributed optical fibre strain measuring system

A testing instrument or testing system that can complete strain distribution testing by simply accessing one end of the optical fiber under test.

Note 1. Including Brillouin optical time domain reflectometer, Brillouin optical frequency domain reflectometer, etc.

Note 2. This document is referred to as "single-ended system".

3.4 Loop-type distributed optical fibre strain measuring system

A test instrument or test system that can complete strain distribution testing by connecting both ends of the optical fiber under test.

Note 1. Such as Brillouin optical time domain analyzer, Brillouin optical frequency domain analyzer, etc.

Note 2. This document is referred to as "loop system" for short.

3.5 Brillouin

A nonlinear scattering effect involving acoustic phonons.