Optical strain gages (FBG-sensors)

The optical strain gages measure mechanical strain by using a glas fiber wire fiber optic cable, in which a microfine grating structure is inserted. White light is introduced into a glass fiber and is reflected at a certain wavelength depending on the grating spacing.

Measurement is carried out by so-called interrogators that carry out spectral analysis of the light reflected in the glass fiber and convert the shift of the wavelengths into levels of strain.
100 measuring points can be measured per fiber.

Typical fields of application are:

• wind power plants
• explosion hazard zones
• aircraft
• sails of sailing boats and yachts
• undersea cables
• composites with high mechanical load
• measuring points with strong electrical interfering fields

Since no electric current flows, these strain gages are suitable for applications, in which strong electric interference fields occur, in which an increased risk of lightning exists, or a risk of explosion caused by flammable gases and/or dust. FBG strain gages are extremely elastic and measure strains of more than 10,000 µm/m, making them highly suitable for composites subject to high level of stress force. It is possible to install wires spanning a length of many miles without suffering losses or requiring repeaters.