Longer FBGs have a higher reflectivity, but are narrower in wavelength. Our SmartScan instrument range is optimised for best accuracy and resolution with 2 mm or 5 mm FBGs. SmartScope instruments can accommodate narrower FBGs and fiber optic sensors with different spectral features.
You may need to choose the length of the FBG based on the size and strain distribution of the substrate you are planning to measure. E.g., choose a FBG smaller than the substrate length. Also, if there is a strong strain gradient where you want to measure, a shorter FBG is better because the reflection peak of a longer FBG is more likely to become distorted and hard to measure.
Please Email Technical Support or call +44 1344 484111 if you need more help on this point.