Fiber Coating Geometry
The Coating Geometry of the optical fiber has a direct influence on its micro bending sensitivity so it is important to ensure that its geometrical characteristics are within allowable limits.
The coating geometry is frozen at the time of manufacturing but it does drift throughout the life of the fiber. In addition, most cablers apply a coloured layer to the coating prior to cabling, so it is useful and indeed good practice to measure the total diameter of the coated fiber 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.