FIELD: measuring equipment.
SUBSTANCE: invention relates to measuring equipment using optical fiber, to fiber-optic security detectors. An optical circuit of a fiber-optic security detector, which uses combined interferometers, is claimed, containing closed and open loops forming reflection signals, in which the same segments of optical fiber of a cable are sensitive elements of interferometers, in which a phase shift of a probing pulse is created according to the applied physical impact, the same for both loops. In this case, the closed loop is a Sagnac interferometer, and the other open loop is a Michelson interferometer, while the optical circuit is placed in a connecting coupling.
EFFECT: increase in the accuracy of determination of a place of impact to a sensitive element; provision of uniform sensitivity of a sensitive part; increase in the reliability of a fiber-optic security detector; simplification of mounting; implementation by the invention of its purpose.
5 cl, 12 dwg
