Optical fiber sensor networks - Applications

Since the first R&D work on the use of optical fibers for measurement in the late 1970s, numerous technical advances have been made, both in terms of fibers and end components, driven by the telecoms sector, and in terms of optoelectronic interrogation systems. As early as the 1980s, sensor networking became a technical and economic necessity if demonstrators were to be taken out of the laboratory and into industry. Thus, by successively using the three phenomena of light scattering in the fiber core - Rayleigh, Raman and Brillouin effects - distributed sensor networks with innovative functionalities were developed, and then brought to market. At the same time, a complementary approach, based on the phenomenon of photo-inscription in the core of optical fibers, has enabled the development of Bragg grating sensors addressing numerous measurands, and which can be networked with various multipoint sensor topologies, in particular thanks to spectral multiplexing techniques similar to those used in modern optical telecoms.

These techniques are now available on the market, and the equipment used is increasingly high-performance. In fact, many application sectors use them to replace or complement traditional techniques, but above all to benefit from their new functionalities, such as "continuous" measurements over several tens of kilometers using a single fiber, or rapid, ultra-insulating measurements at the heart of materials.

Many applications for RCFO fiber optic sensor networks, whether distributed or distributed, can be conceptually grouped under the heading of "structural and materials monitoring". These may include natural structures, civil engineering constructions, fire detection, monitoring of onshore and offshore oil pipelines, perimeters and borders, manufacturing and health control of high-value-added composite structures such as in aeronautics, or even extreme areas such as those found in the nuclear power industry.

In each of these sectors, year after year, advances are being made thanks to RCFOs, and of course to the players who develop and implement them. This article presents the most relevant sectors in terms of distributed RCFO applications. The text is enriched by numerous supplements relating to the field of CFO and RCFO, which can be consulted thanks to the references and Internet links of the various players making up this community.

The main techniques and instruments for measuring OFDM (OTDR, OFDR, FMCW, DTS, BOTDA, BOTDR, BOFDA, BOFDR, DAS, DVS, etc.) are described in the previous article [R 460] .