Fiber Optical Sensors

For Precise Measurement in Demanding Applications With Maximum Flexibility in Sensor Design.

Fiber Optics: Precise Measurement With Maximum Flexibility

Using fiber optic measurement solutions (WLPI: White Light Polarisation Interferometry) from ALTHEN, you can measure strain, pressure, displacement, or temperature. Conventional electronic sensors are often hampered by distorting effects such as high voltage or EMV. This is where our systems come to shine: They open up new possibilities for reliable measurements, especially in the most challenging environments.

Properties and advantages of Fiber Optic Sensors

  • High immunity: No sensitivity to high voltage and electromagnetic disturbance.
  • Long-term stability: No optical losses due to shifting or bending fibers or connectors.
  • Superior ruggedness: The sensors are rugged and suitable for the most demanding applications.
  • Simple installation: Easy length adjustment of optical fibers, mounting via spot welding, gluing, or full integration into components.
  • Lightweight and compact form factor: The sensors can be very small.
  • Versatility: The same signal evaluation unit can capture all measured quantities mentioned above.
  • No maintenance: No calibration or maintenance required.
  • Intrinsically safe: The sensors are suitable for high voltage environments, ATEX protection areas, as well as chemically aggressive environments.

WLPI: Possible Applications for Fiber Optic Sensors

  • Manufacturing
  • Aerospace
  • Defense
  • Geotechnical applications
  • Construction
  • Structural monitoring
  • Energy / renewables
  • Chemical industry

Food and beverage industry

The experts at Althen call on more than 40 years of experience to offer the perfect solution tailored to your requirements. This also includes custom fiber optic and fully integrated solutions. Your advantage: We provide independent advice and do not limit you to one manufacturer. At your request, we tailor measurement systems to your specific needs. We are happy to answer any questions you might have.

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Fiber Optical Sensors for every application: Our product portfolio

Find the perfect pressure sensor for your application. We’d be happy to help you choose.

Fiber Optic Sensors – Perfect for the Most Challenging Applications

Fiber Optic White Light Polarisation Interferometry (WPLI) is patented fiber optic technology which enables precise measurements to be made in the most challenging of applications. It offers maximum flexibility in sensor design such that reliable measurements can be generated even in extremely unfavorable environments.

This includes:

  • Simple adjustment of optical fibers,
  • easy mounting,
  • and the possibility to fully integrate sensors in components even as small as a credit card. Including all components required for signal evaluation.

And a single signal evaluation unit can capture all measured quantities offered.

Fiber Optic Sensors: Our Product Range

Fiber optic strain sensors enable precise measurements of deformation. Possible applications include the following:

  • Structural monitoring
  • Detection of microfissures and localized material defects
  • Measurement of rotor blade load in wind turbines
  • Manufacturing optimization in lightweight engineering
  • Vibration analysis

Our Fiber optic pressure sensors enable high-precision pressure measurements, even in the most demanding environments. Thanks to their small form factor, high immunity, and great reliability, these sensors are suitable for many applications, such as

  • Scientific research
  • Industrial applications

Fiber optic position sensors boast long life cycles and are suitable for the most demanding applications that require absolute reliability. They are ideal for all industrial applications, including

  • Real-time structural monitoring
  • Monitoring of concrete structures
  • Structural monitoring in aircraft

Fiber optic temperature sensors are used for creating temperature profiles. One typical fiber optic temperature sensor is the single point sensor, which is attached to the end of a fiber. Optical fibers are resistant against electromagnetic radiation. That allows them to be used even in high voltage gradients, explosive environments, or chemically aggressive environments without problems. Typical applications include the following.

  • Monitoring in Magnetic Resonance Imaging (MRI)
  • Process monitoring in pipe reactors
  • Analysis drilling cores and leak detection

Our Fiber Optical Sensors in Use

Would you like to get to know our products in practice? Take a look at these interesting projects from our customers:

WLPI Technology explained

White light polarization interferometry (WLPI) technology offers a great degree of flexibility in the design of various types of fiber optic transducers. How does WLPI work?

Advantages of Fiber Optical Sensors

Fiber Optical Sensors is a new technology based on White Light Polarization Interferometry (WLPI), which offers great benefits. Read more.

How does fiber optic WLPI technology work?

Fiber optic white light polarisation interferometry is a patented technology. It enables precise measurements in the most demanding applications. WLPI allows great flexibility in sensor design for reliable measurements even in the most challenging environments.

Fiber optic measuring systems comprise two main components: the fiber optic sensor and a signal processing unit. The fiber optic sensor consists of a sealed housing that contains the optical sensor element and an optical fiber, which serves different purposes depending on the technology used.

There are several fiber optic measuring procedures based on different properties of light (intensity, phase, polarisation, or spectrum). Depending on the procedure, variations in the designated measurement quantity causes one or more of these properties to change, so that the returning signal is altered.

Extrinsic and Intrinsic Sensors

Fiber optic sensors can be divided into two main categories: extrinsic and intrinsic sensors. They differ both in design and function, featuring specific properties that make them suitable for different applications.

In intrinsic sensors, the light conductor is an essential component of the measurement mechanism. The optical fiber is the sensor. Common examples of this category include sensors based on Fiber Bragg Grating.

Extrinsic sensors, on the other hand, are characterized by the sensitive component being separate from the optical fiber. The optical fiber merely transmits the light signal between the sensor unit and the evaluation electronics. Examples of extrinsic sensors include temperature sensors based on gallium arsenide crystals (GaAs) as well as the WLPI-based fiber optic sensors presented below.

Precise Optical Measuring Procedure

The signal evaluation unit feeds the light signal into the optical fiber, receives the reflected, altered signal, and processes it to output physical units of the measured quantity. The light source used can differ depending on the measuring procedure and technology.

Optical interferometry, which measures the phase modulation of light, is considered the most sensitive method of fiber optic measurement. An interferometer is a high-precision optical measurement device featuring two or more light beams that are guided on different paths through semi-transparent mirrors before being reflected and recombined by another set of mirrors. This results in an interference pattern which is determined by the difference between the optical paths taken by the individual beams before their recombination/superimposition.

Using interferometry lets you measure a physical quantity whenever variations in that quantity cause variations in the path length in the interferometer.

Laser vs. White Light

The lasers used as light sources in conventional fiber optic sensors led to issues with phase ambiguity due to their narrow bandwidth. This was due to the coherence length of the light source generally being larger than the difference in wavelength in the interferometer. As a result, possible applications for fiber optic sensors based on interferometry were limited. The solution to this problem lies in using a light source with a shorter coherence length and broader light spectrum.

This kind of interferometry is called white light interferometry or optical coherence tomography. The founders of Opsens are pioneers in white light interferometry for fiber optic measurements. They have refined this technology to commercial viability.

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