An introduction to fiber optic sensors

Our society is increasingly demanding measurement and control instruments of all kinds, whether for safety, comfort or product quality control. The development of electronic systems has made it possible to design reliable measuring devices, which are now tried and tested and highly sophisticated. Their miniaturization means that they can be used in large quantities and in increasingly non-intrusive ways.

To this end, optical fibers offer excellent properties, such as very low intrusivity, insensitivity to electromagnetic radiation and rapid transfer of large quantities of information. Their potential is therefore not limited to replacing electrical cables. Fiber optic sensors exploit the intrinsic sensitivity of optical fibers to variations in their environment (temperature, pressure, mechanical stress, etc.). This type of sensor is an ideal replacement for traditional instrumentation in demanding environments such as the nuclear industry, or in humid or high-temperature environments. As a general rule, for most applications, they offer performances comparable to those of electronic sensors in terms of accuracy and sensitivity, although the latter have the advantage of having been tried and tested for longer by users in the field. The real technological breakthrough with fiber optic sensors comes from the distributed nature of the measurement they provide. Thanks to dedicated instrumentation that localizes the measurement along the optical fiber, a single optical fiber can be considered as a large set of cascaded sensors.

The aim of this dossier is to present the physical principles of the main fiber optic sensor configurations, and then to summarize their performance.