Compact Portable Double Differential Fiber Optic Sagnac Interferometer

摘要

A compact and portable apparatus for measuring properties of objects utilizing a fiber optic Sagnac interferometer is enabled. The fiber optic Sagnac interferometer may be a double differential Sagnac interferometer. The interferometer core may be implemented with fiber optic components including polarization maintaining optical fiber, and by utilizing an auto-balanced avalanche photodetector. An optical switch may be incorporated to maintain relatively low average probe signal power while allowing optimal peak probe signal power. The compact and portable apparatus may be configured to measure ultrasonic vibrations, a displacement of an object surface in response to ultrasonic vibrations, and/or a vibration speed of the object surface. A wideband light source may be amplified and stabilized. A sensor head of the interferometer may incorporate a collimator adjustable to block a central portion of the projected probe beam thereby at least in part enabling in-plane and out-of-plane measurements.

主权项

1. A system for measuring a property of an object, comprising:
a Sagnac interferometer including a first length of optical fiber and a second length of optical fiber having a minimum bend radius, the second length of optical fiber arranged in a coil with an internal diameter substantially corresponding to twice a minimum bend radius of the second length of optical fiber; a photodetector optically coupled with the Sagnac interferometer; and an assembly configured to contain at least the Sagnac interferometer and the photodetector, the assembly having a maximum internal dimension substantially corresponding to the internal diameter of the coil added to twice a maximum diameter of the second length of optical fiber.