• fos4Test

    Fiber-optic measurement technology

Universal fiber-optic measurement module

The new fos4Test fiber-optic measurement amplifiers from imc enable precise measurements with fiber Bragg-based sensors.

Equipped with 4 channels, the Expert version of the measurement amplifiers acquire the signals of the FGB sensors at a sampling rate of up to 25 kHz per channel - without aliasing.

Simple integration and convenient operation

The systems can be quickly and easily connected to a PC or company network via an Ethernet interface. The operation, visualization and storage of the measurement is carried out comfortably via the imc STUDIO measurement software.

Synchronous measurements with all imc measurement systems

Together with the fiber-optic measurement modules, all other imc measurement systems can be operated synchronously in one measurement. This allows FBG sensors and traditional electrical sensors to be used in one application e.g., for pressures, speeds, sounds, etc.

The advantages at a glance

  • High-precision measurements even in tough environmental conditions
  • Aliasing-free measurement (fos4Test expert)
  • High sampling rates up to 25 kHz (fos4Test expert)
  • Multiple sensors per fiber possible (fos4Test nSense)
  • Synchronous measurement with all imc measurement system families via imc STUDIO
  • High-precision synchronization using precision time protocol (IEEE-1588)
  • Connection of additional electrical sensors

Device variants of the fos4Test series

fos4Test expert

For demanding measurement tasks:

  • 25 kHz sampling rate per channel
  • 4 channels
  • 1 sensor per channel
  • < 1 pm measurement uncertainty
  • Rack mounting possible
  • Configuration, operation and visualization via imc STUDIO

fos4Test nSense

For multi-channel measurement tasks:

  • 100 Hz sampling rate per channel
  • 4 channels
  • Up to 9 sensors per channel
  • < 0.1 pm measurement uncertainty
  • Rack mounting possible
  • Configuration, operation and visualization via imc STUDIO

FBG sensors from imc

Torque sensor: fos4Strain

The fos4Strain sensor is a fiber-optic strain sensor based on a fiber Bragg grating.

Product highlights:

  • Measures high strain up to ±4000 µm/m
  • Reliably measures more than 108 load cycles
  • Is insensitive to electromagnetic interference
  • Enables precise measurements on inhomogeneous structures such as glass-fiber-reinforced plastics, which usually exhibit an inhomogeneous strain distribution on their surface.

Special features

The fos4Strain strain sensor offers three major advantages over simple fiber Bragg grating sensors:

  • Compensates for the influence of temperature on the strain measurement

The special design of the sensor counteracts and compensates the thermal expansion of the structure. This allows the temperature strain cross sensitivity to be counteracted.

  • Compensates for structural inhomogeneities

Material inhomogeneities, such as are common with fiber composites, generate locally inhomogeneous strain fields. The integrating design of the transducer avoids resulting measurement errors.

  • Is compatible with anisotropic materials

Different temperature expansion in different spatial directions is a normal property of structures made of fiber composite materials. The sensor also compensates for this.

Accelerometer: fos4Acc

Accelerometers are widely used in many areas. With the fos4ACC accelerometer, the advantages of fiber-optic measurement technology can now be applied in acceleration measurement. The possible fields of application are versatile: lightweight construction, automotive, aerospace, mechanical engineering, medical technology, energy and many more.


  • Acceleration measurements under demanding environmental conditions

Due to optical measuring methods, the sensor is insensitive to electromagnetic interference and can be used, for example, in high-voltage areas or in explosive environments.

  • Easy to mount

The sensor can be attached to the test object with a screw or magnetically. This makes the sensor easy to handle and reusable many times over.

  • Resonant frequency up to 200 Hz

The sensitivity and resonance frequency of our fiber-optic accelerometer can be adjusted over a wide range. This results in a vast range of applications from vibration measurement on lightweight structures to powertrain monitoring and medical applications.

Additional features

  • Measurement bandwidth up to ±100 m/s²
  • Sensitivity up to 10 g/nm
  • Measurements at  -20 °C to 50 °C possible
  • Measurement range ±10 g

Additional sensors

Fiber Bragg gratings can measure both strain and temperature. A wide range of physical quantities can be measured using transducers.

The advantages of fiber-optic measurement technology can thus be used in a wide range of applications.

Fiber-optic sensors are suitable for many applications

Many physical quantities can be measured using transducers equipped with fiber Bragg gratings:

  • Strain
  • Temperature
  • Acceleration
  • Force
  • Torque
  • Pressure

In the fos4 series, special sensors are already available for many applications. In addition, many of the sensors available on the market are compatible with the fos4Test system. Contact us and we will be happy to advise you on the choice of the right sensor for your application.

Special sensors for special tasks

Depending on the application, the concrete sensor designs may have to be adapted: From "bare" sensor fibers to rosette and half-bridge arrangements to complex force-torque sensors. We have a comprehensive set of methods and are happy to support you in finding individual solutions to your measurement problems.

In Practice

Whether wind turbine, automobile, aircraft or industrial plant - precise assessments of the structures with regard to ageing behavior, load capacity and maintenance requirements are decisive. Conventional strain gauges quickly reach their limits: Too many load changes, too high amplitudes, too little installation space, too high of demands on the precision of the measurement.

Fiber-optic sensors are ideal for demanding tasks. For example, fiber-optic strain sensors can withstand 1,000 times more load changes at amplitudes up to 10 times higher than traditional strain gauges. In addition, they require less installation space and are insensitive to interference. This results in very high reliability. This opens up new possibilities both for testing prototypes and for monitoring the operation of technical structures.

Wind Energy

Fiber-optic load measurements on the rotor blade of a wind turbine enable you to measure the dynamic load change occurrences. Strains in the blade root and induced accelerations in the blade center of gravity are measured.

This data is used to calculate further information that is relevant for plant control, monitoring, certification and insurance purposes: Maximum loads, blade bending moments, lifting moments, rotation rates, azimuth angles, wind direction, stiffness changes, order analyses, etc.

Blade load measurements and condition monitoring can help to reduce the maintenance costs of wind turbines and increase their yield.

Structure Monitoring

The ability to use very long sensor cables or to integrate several sensors in one measurement cable (chain setup) is ideal for monitoring buildings and bridges. The monitoring of dams is therefore also an easy application to implement.

Railway Industry

Its insensitivity to electromagnetic interference makes fiber-optic measurement technology ideal for vibration measurements on bogies and pantographs. The solution is also suitable for monitoring rail lines.

Automobile Industry

Fiber-optic measurement technology offers a wide range of applications in vehicle manufacturing. From structural analysis of lightweight components to reliable measurements of live parts such as batteries, fuel cells and electric drive trains.

Chemical Industry and Power Plants

Due to their technical properties, fiber-optic sensors can be used in potentially explosive atmospheres and are therefore particularly suitable for measurements in refineries, power plants or drilling platforms.

imc Test & Measurement is an Axiometrix Solutions company.