METHOD OF MEASURING OPTICAL LENGTHS AND DELAYS OF FIBER LIGHT GUIDES AND OTHER FIBER-OPTIC ELEMENTS Russian patent published in 1995 - IPC

FIELD: measurement technology. SUBSTANCE: linear dependence of phase shift of modulated optical signal in light guide on modulation frequency f is used for realization of the method. As phase difference meters are able to measure phase shift only in 2π boundaries, the electric signal frequency should be changed according to the method which modulates intensity of optical radiation passing through the light guide. Two values f₁ and f₂ of frequencies are fixed which correspond to two sequent "zero" countings of phase differences of signals in channels of two-channel measuring device; in this case channels of light guide measured or other passive fiber-optic element are disconnected. After that two sequent countings f₃ and f₄ are fixed which correspond to two sequent countings of phase differences of signals in channels but taking into account that one channel of light guide measured is connected to the circuit. Optical length of the light guide to be found and measured as well as signal delay in passive fiber-optic element are calculated from the relation given in the description of the invention. EFFECT: simplified process of measurement: improved precision. 3 dwg