Curl in an optical fiber is a by-product of the stresses that exist at the manufacturing stage and are frozen into the fiber. The curl does not generally change throughout the life of the fiber.
The degree of curl in the fiber is interesting as it has a known influence on the usability of a particular fiber in a ribbon structure. When attempting to splice a ribbon fiber structure, the effect of any curl exhibited by the fiber will be visible in the splicing machines display and will result in one or more of the the splices in the ribbon having higher than normal loss.
Like most optical characteristics, the curl of the fiber is frozen at the time of manufacturing and is not known to vary throughout its operating life. It does however vary along the its length and so it is useful and considered good practice to measure the curl even within a cable manufacturing environment to ensure the consistency of the product.
The 'Production/Lab/R&D' range is suitable for manufacturers of fiber and cables. It is considered unlikely that this measurement would be required in a field environment.