Optical strain gauges are generally made of Bragg grating glass fibers not exceeding 4-9 microns in diameter.
In general, the diameter of a human hair is 60-80 microns. The fiber core is surrounded by a pure glass covering of approximately 125 microns in diameter.
Strain gauges based on Bragg grating have the following advantages:
1. Insensitive to electromagnetic fields
2. It can be used in an environment that may explode
3. In the case of high vibration load, the material (glass) will not cause failure
4. Larger strains can be measured, the maximum strain of the general resistance strain gauge is hundreds of microstrains, while the maximum strain that can be measured by the optical strain gauge is 7000 microstrains
5. Fewer connections, so there is less interference with the test object
6. Interconnections require a large number of sensors, and different Bragg wavelengths can be integrated in a single fiber.
