Equipment for measuring the length of dielectric elements transmitting optical frequencies

摘要

An equipment for measuring length or refractive index of a dielectric element capable of transmitting optical frequency signals, for instance an optical wave guide. The used method consists in making at least one measurement of the propagation time of a light impulse over a length of the said element, and deducing therefrom the unknown length or index, if one of the latter is previously known. The equipment includes an injector of light signals, a separator dividing each light pulse signal into a delayed and a non-delayed one respectively transmitted through a first and a second path one of which contains the dielectric element to be measured and the other of which is used as a comparison one, a detector at the output of each of said paths, and a viewing element displaying the outputs of both detectors on a common screen, for instance that of an oscilloscope whereby the propagation time difference between said paths is translated into the spacing between the said outputs observed on said screen.