Fiber-diffraction Interferometer using Coherent Fiber Optic Taper

TL;DR

This paper introduces a fiber-diffraction interferometer utilizing a coherent fiber optic taper and a single-mode fiber with a thermally-expanded core, enabling stable optical testing even in uncontrolled environments by stabilizing interference fringes against vibrations and focus shifts.

Contribution

The novel use of a coherent fiber optic taper combined with a thermally-expanded core single-mode fiber enhances stability and robustness of fiber-diffraction interferometry in challenging conditions.

Findings

Interference fringes remain stable despite target movement.

The system effectively suppresses focus shift effects.

Vibration-induced phase noise is minimized.

Abstract

We present a fiber-diffraction interferometer using a coherent fiber optic taper for optical testing in an uncontrolled environment. We use a coherent fiber optic taper and a single-mode fiber having thermally-expanded core. Part of the measurement wave coming from a test target is condensed through a fiber optic taper and spatially filtered from a single-mode fiber to be reference wave. Vibration of the cavity between the target and the interferometer probe is common to both reference and measurement waves, thus the interference fringe is stabilized in an optical way. Generation of the reference wave is stable even with the target movement. Focus shift of the input measurement wave is desensitized by a coherent fiber optic taper.