Fibre optic sensing has become a popular method of measuring changes in temperature, strain and other variables, using light as the detector when it travels along a fibre.
Fibre optic sensing is often selected in applications where size may be an issue, or in more remote project locations where there is no electrical power. It is a useful tool; a number of sensors can be multiplexed along the length of a fibre using light wavelength shift for each sensor, or by sensing the time delay as light passes through each. Time delay can be determined using a device such as an optical time-domain reflectometer (OTDR); wavelength shift can be calculated using an instrument implementing optical frequency domain reflectometry.
Another advantage offered by fibre optic sensors is their immunity to electromagnetic interference. They don’t conduct electricity and can be used in applications in which there might be high-voltage electricity or flammable material. They are also designed to withstand higher temperatures.
Demand for these properties is helping to grow the market. According to the latest report from ResearchAndMarkets.com, the global market for fibre optic sensors is forecast to reach $4.9bn by 2025 from $2.9bn in 2020. This marks a compound annual growth rate (CAGR) of 10.9 per cent for the forecast period.
The Global Fiber Optic Sensors Market 2020-2025 report stated that shortcomings and limitations of traditional sensing technologies have partially paved the way for fibre optic sensing. Optical fibres, it said, are light-weight, passive and unobtrusive sensing wires with a thickness comparable to a human hair.
Using this technology additionally allows movement away from traditional discrete measurement points to continuous measurements visualising strain and temperature gradients, pressure, multi-directional force, curvature and shape information.
In terms of applications, fibre optic sensing is benefiting a number of industries from industrial processing, structural health monitoring and energy to aerospace, medical and safety and security.
According to the report, the greatest market success can be found where the attributes of optics can’t be replicated. Medical and defence, for example, are markets in which optics have a distinct advantage over competing electronic options. Medical applications also offer growth potential, should the devices obtain the appropriate approvals for use in humans.
Fibre optic sensing technology on the market now
Vendors offering fibre optic sensing technology include Analog Devices, which provides optical sensing devices designed to achieve very high signal-to-noise ratios at low power. The company’s portfolio spans a wide range of wavelengths in an IC form factor, from UV to 1600nm in the near IR for use in healthcare, automotive and industrial applications.
Balluff fibre-based devices for plastic and glass fibres are designed for when a conventional optical sensor might be too large or too rigid for an application. They can be combined with plastic or glass fibre optics for a complete sensor so that – depending on the application – the maximum amount of flexibility is available.
Baumer’s collection of universal fibre optic sensors is particularly useful in material-handling applications where besides rapid process monitoring, accurate positioning or detection of small objects can be everyday occurrences. One single sensor assumes the tasks where previously many different ones would have been used. The user can select between 3 to 8 different operating modes, from short response time to high sensitivity.
Broadcom offers fibre sensing technologies and the related infrastructure for effective system and application integration. These technologies generically enable light-weight industrial sensor design, providing high electromagnetic interference (EMI) immunity and low electromagnetic susceptibility (EMS).
As for the cables themselves, Corning provides distributed sensing cables. These are designed to be robust for reliability in harsh conditions with no tradeoff in sensitivity. The design enhances and amplifies sensor signal delivering to deliver high operational performance.
Fibre sensor components from Coherent are designed to help OEMs build fibre optic gyroscopes, delay lines and current sensors with precision-wound coils. They have commercial to strategic grade coils for automotive, space and defence applications and are available in small form factors, as well as a variety of patterns and lengths.
Emcore’s lasers for optical sensing support technologies such as Lidar, strain measurement, tracking, terahertz-spectroscopy, position and interference measurement, interferometry and free space communications. Components can be custom designed in a variety of form factors to integrate into a wide range of industrial applications such as autonomous vehicles, oil and gas exploration, materials characterisation, aerospace, astronomy and more.
Hamamatsu Photonics has a wide range of optical sensors available including photodiodes for a broad spectral range, in metal, ceramic and module types; avalanche photodiodes (APDs) with internal gain produced by the application of a reverse voltage; photo IC with diverse functions and integrated photodiode with signal processing IC; multi-pixel photon counter (MPPC); phototubes and photomultiplier tubes. The company also supplies spectrometer/ spectrum sensors, infrared detectors, UV & flame sensors, x-ray, radiation, electron & ion sensors, distance & position sensors and application-specific sensors.
Highland Technology offers precision analog measurement and signal generation, data acquisition and control instrumentation, pulse and picosecond timing delay generation, laser diode drivers, waveform generators and fibre optic, photonics and mixed technology products for demanding aerospace, defence, scientific and industrial applications.
Luna Innovations provides fibre optic-based test products for the telecommunications industry and fibre optic-based sensing solutions for infrastructure, aerospace and automotive industries. The company’s sensing solutions are used in applications such as structural analysis, material testing and structural health monitoring applications.
OZ Optics’ Foresight series of fibre optic distributed strain and temperature sensors (DSTS) use Brillouin scattering in optical fibres to measure changes in temperature and strain along the length of an optical fibre. By wrapping or embedding a fibre inside a structure — such as an oil pipeline or dam — one can detect when the structure is being strained or heated/cooled and correct the problem before failure occurs.
TE Connectivity manufactures a broad range of sensor types for applications across a wide range of industries, including automotive, aerospace and defence, appliance and industrial, medical and commercial transportation. This includes sensors in cars and sensors for home systems, sensors in blood pressure devices and sensors for robotics.
Yokogawa carries a variety of sensor products and services that aim to meet the needs of various industries. The company offers products and solutions for modern process needs such as high-performance sensors, which ensure stable and high-precision performance under all circumstances. The ability to accurately and reliably measure pressure, flow, temperature and level rate is ideal when trying to control a process, while the use of process analyzers is essential to determine the chemical composition or physical properties of substances involved in industrial processes.
This is not an exhaustive list. If you provide fibre optic sensing solutions and would like your company to be included, please let us know.
