Fiber diameter measurements and their calibration

Seeks to establish a high level of confidence in fiber cladding diameter measurement by the use of three methods: white light interferometry, mechanical contact, and image inverting microscopy. Calibration with transfer fibers is considered unattractive because of the difficulty of maintaining the calibrated cleaved end. The uncertainties involved in calibrating other methods are investigated, namely image shear, grey scale digitization, and refracted near field, using chromium on glass circular patterns or lines. Their use is found to give consistent results with uncertainties not exceeding ±0.15 μm. Experimental arrangements are discussed. There are some sources of measurement error, but these can be overcome so that measurements of fiber diameter with an uncertainty of less than ±0.15 μm look feasible using chromium on glass calibration standards