Chat with us, powered by LiveChat

Careers | Training | Resource!!!

arrow_back_ios

Main Menu

See All Products See All Knowledge See All Services & Support See All Solutions See All About See All Contact Us See All Demo See All Load cells title
arrow_back_ios

Main Menu

See All Acoustic End-of-Line Test Systems See All DAQ and instruments See All Electroacoustic application See All Software See All Transducers See All Vibration Testing Equipment See All Electroacousticsb - OLD unpublished See All Academy See All Resource Center See All Services See All Support See All Applications See All Industries See All Our Business
arrow_back_ios

Main Menu

See All Actuators See All Combustion Engines See All Durability See All eDrive See All Transmission Gearboxes See All Turbo Charger See All DAQ systems See All High precision and calibration systems See All Industrial electronics See All Power Analyser See All S&V Handheld devices See All S&V Signal conditioner See All Accessories for electroacoustic application See All DAQ See All Drivers API See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All Utility See All Vibration Control See All Acoustic See All Current / voltage See All Displacement See All Load cells See All Pressure See All Strain Gauges See All Torque See All Vibration See All Temperature See All LDS Shaker Systems See All Power Amplifiers See All Vibration Controllers See All Accessories for modal exciters See All Test Solutions See All Training Courses See All Primers and Handbooks See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Acoustics See All Asset & Process Monitoring See All Electric Power See All NVH See All OEM Custom Sensors See All Structural Integrity See All Vibration See All Automotive & Ground Transportation See All Business Ethics
arrow_back_ios

Main Menu

See All CANHEAD See All GenHS See All LAN-XI See All MGCplus See All Optical Interrogators See All QuantumX See All SomatXR See All Fusion-LN See All Accessories for industrial electronics See All Handheld Software See All Accessories for S&V handheld devices See All BK Connect / PULSE See All API See All Microphone sets See All Microphone Cartridges See All Acoustic calibrators See All Special microphones See All Microphone Pre-amplifiers See All Sound Sources See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All Accessories for strain gauges See All Non-rotating (calibration) See All Rotating See All CCLD (IEPE) accelerometer See All Charge accelerometer See All Impulse hammers / impedance heads See All Cables See All Accessories See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All Resources See All Electroacoustics See All Environmental Noise See All Noise Source Identification See All Product Noise See All Sound Power and Sound Pressure See All Vehicle Pass-by Noise See All Production Testing and Quality Assurance See All Machine Analysis and Diagnostics See All Structural Health Monitoring See All High Voltage See All OEM Sensors for the Agriculture Industry See All OEM Sensors for Robotics and Torque Applications See All Structural Dynamics See All Material Properties Testing
null

Optical Strain Measurement Glossary

A useful guide of technical terms to help you understand the precise concepts related to the fundamentals of strain measurement using optical strain sensors.

List of Terms related to Strain Measurement with Optical Sensors

λ Wavelength

Wavelength is the measured peak wavelength of a fiber Bragg grating sensor. It is normally expressed in nanometers (nm).
λ0 Reference wavelength

The reference wavelength is the peak wavelength of a fiber Bragg grating sensor at a reference condition (zero strain, at reference temperature, and so forth.. It is normally expressed in nanometers (nm).
Δλ Wavelength variation

The wavelength variation (also commonly referred to as shift or as change) is the difference between the wavelength and the reference wavelength (reference value): Δλ= λ- λ0. It is normally expressed in nanometers (nm).
k k-factor The gauge factor k (also referred to as k-factor) of an optical strain gauge is the proportional change in the Bragg wavelength (Δλ/λ0) and the strain variation Δε. Is is being measured as: Δλ/λ0 = k.Δε. This value is a dimensionless number and depends on the characteristically used optical fiber and sensor encapsulation. In the case of HBM optical strain sensors, the k-factor is identified on the data- and calibration sheets that are individually delivered with each sensor.
ε Strain

Strain is a dimensionless value that represents the relative change in the length of a material to its initial length. It is normally of a very small value, and hence is represented by µm/m, ppm or 10-6.
S Sensitivity

The sensitivity of an optical strain sensor is the direct ratio between the measured strain and the change in the Bragg wavelength: Δε/Δλ= S. It is normally stated as value in micro-strain per nanometer [(µm/m)/nm)] and is different for every sensor, as it depends on its initial base wavelength, that is: S=1/(k. λ0).
 TCS Temperature cross-sensitivity

The temperature cross-sensitivity is a sensor measurement drift caused by temperature variation. It is the strain that is wrongly measured when there is a change of 1ºC (or 1ºK) in temperature. The value is given in (µm/m)/ºC [or (µm/m)/ºK] and can be used to compensate the effect of temperature on the optical strain sensor (not considering the compensation for the thermal expansion of the specimen).
σ Stress

Mechanical stress is expressed by the quotient of the force F and the cross-sectional area A of the stressed material, σ=F/A. It is normally represented in KPa.
E Elastic modulus

The modulus of elasticity, or Young’s modulus, is the ratio between stress and strain in a linear elastic material. It is given by Hooke’s Law (σ=E.ε). It is normally represented in GPa (109 Pa) to correlate strain in µm/m (10-6) with stress in KPa (103 Pa).
v Poisson's ratio

Poisson's ratio is defined by the division of the transverse strain εt and the longitudinal strain εl. For aluminum alloys, ν = 0.33, for example.

Recommended for you

No more result to load

Modern Slavery Statement     Imprint    Cookie Policy    Privacy Policy    Sitemap    Ethical Business

 

© 2025 Hottinger Brüel & Kjær

 

 

close
nCode logo
Graphics Brand

We haved moved ${referer} to www.hbkworld.com

 

This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.

close
ReliaSoft-Logo-webp
Graphics Brand

We haved moved ${referer} to www.hbkworld.com

 

This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.

close
Prenscia HBM-Logo rgb
Graphics Brand

We haved moved ${referer} to www.hbkworld.com

 

This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.

close
HBM-Logo blue rgb
Graphics Brand

We haved moved ${referer} to www.hbkworld.com

 

This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.

close
logo of Brüel & Kjær (BKSV), experts of sound and vibration measurements from HBK
Graphics Brand

We haved moved ${referer} to www.hbkworld.com

 

This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.