OptiMet by HBM™ - System for Fiber-Optic Sensors

Intrinsic Sensors Ensure Efficiency and Reliable Measurement

When the optical fiber itself forms the sensor element and is used for transmitting measurement data, we refer to an intrinsic, fiber-optic sensor.

In specific applications, fiber Bragg grating-based strain gauges are superior to their electrical equivalents. HBM has completed its range of electrical and optical strain gauges with the OptiMet by HBM™ system of fiber-optic components with and without integrated Bragg grating measurement function.

The OptiMet systems offers single mode optical fibers with integrated functional grids.

  • OptiMet-OMF (optical fiber with Bragg gratings):
    OptiMet-OMF is a singlemode optical fiber. By default, it has 13 fiber Bragg gratings and allows fiber optic strain measurement with a defined gauge factor. Bending radii up to 2.5 mm are possible. OptiMet-OMF is optimally suited for use in laboratory applications.
    Learn more about OptiMet-OMF

  • OptiMet-PKF (optical fiber with Bragg gratings and rugged coating):
    OptiMet-PKF designates a singlemode optical fiber with an additional rugged coating. The standard optical fiber has 13 fiber Bragg gratings and allows fiber optic strain measurement with a defined gauge factor. Bending radii up to 10 mm are possible. OptiMet-PKF is ideally suited for outdoor use.
    Learn more about OptiMet-PKF

Whether in aerospace, geotechnology, or pipeline monitoring, efficiency and reliability are guaranteed!

OptiMet OMF
OptiMet PKF
OptiMet PKF

Applications and Industries

  • ESA - Experimental Stress Analysis
  • Aerospace
  • Automotive
  • Railway
  • Geotechnology
  • Wind power
  • Regenerative energies

Possible Fields of Application

  • Load tests in component development and materials research
  • Fatigue tests
  • Determining static and dynamic loading states
  • Monitoring of settling in pipelines
  • Monitoring during the construction phase (tunnel convergence, elevation, etc.)
  • Monitoring slopes

Advantages Over Electrical Strain Gauges

  • Measurement of high strain values with good resistance to alternating loads
  • Immunity against electromagnetic fields
  • Suitable for use in potentially explosive atmospheres
  • Faster and more cost-efficient installation per measuring point
  • Multiple sensors in a single measuring chain
  • Multiplexing capability
  • Immunity against the effects of humid environments

Configuration and Properties

Figure 1 shows a typical measuring chain configuration.

Fig. 1: Typical configuration for OptiMet OMF and OptiMet PKF

Figures 2, 3 and 4 show OMF and PKF fiber types, each with distinguishing features. The two OptiMet types have the same optical properties:

  • a) Peak form (grid with low reflection characteristics up to 15% reflectivity):

Fig. 2: Typical peak form of Bragg gratings in OptiMet OMF and OptiMet PKF fibers

  • b) Gauge factor: 0.79 (OptiMet-PKF) and 0.78 (OptiMet-OMF)
  • c) Core diameter: 6µm
  • d) Attenuation: 8.6 dB / km (one-way)

The two fiber types are characterized by high stability against alternating load and the capability to absorb high levels of strain.

OptiMet OMF (195µm fiber diameter):

Fig. 3: OptiMet OMF singlemode fiber

OptiMet PKF (700µm fiber diameter):

Fig. 4: OptiMet PKF singlemode fiber

Operating temperature range

The operating temperature range* for the types is:

OptiMet OMF

OptiMet PKF

-269 to 200 °C

-40°C to +100 °C

for a short time up to +300 °C

for a short time up to +300 °C

*)The characteristics of the adhesives used in the installation have not been taken into account

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Measuring with light: A whole bundle of benefits

  • Reduce your installation costs...
    ...because a single fiber can handle multiple measurements.
    With optical strain gages from HBM you benefit from reduced wiring requirements. Several optical strain gages can be used on a single fiber. The optical measurement chain is individually adapted to suit your requirements.
  • Get high-precision test results...
    ...even in difficult environments and materials
    Optical strain gages enable you to test the fatigue strength of your components. Stress testing can be conducted even in materials with high levels of strain, and with high numbers of load cycles. You get consistent and accurate test results even in adverse ambient conditions, for example, in high-voltage systems.
  • Acquire reliable data...
    ... whatever the distance between your optical strain gages and the measurement system.
    The effects of distance and cable length on the test result can be neglected with optical strain gages. Even if your data acquisition system is located many hundred meters from the measuring points, the use of optical sensor technology will not negatively affect the quality of your test results.