METHOD OF MEASURING A SPOT SIZE OF A SINGLE-MODE FIBER

摘要

The invention provides a method of measuring the spot size of a single-mode optical fiber, comprising the steps of measuring the far field pattern of a beam emitted from one end of the single-mode optical fiber in a range from the radiation angle at which the far field pattern is maximum to the radiation angle at which the far field pattern is reduced 25 dB or smaller, calculating the near field pattern from the measured far field pattern by the use of Hankel's transform, and determining the spot size from the calculated near field pattern according to a prescribed definition formula. This method avoids the use of a vidicon camera or lens systems which have produced errors in known measurement systems.