Measurement of small phase shifts using a single-mode optical-fiber interferometer

Abstract

Periodic phase changes in the 10(-6) -rad region have been induced and detected in a single-mode all-fiber Mach- Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10(4) Hz.

Foreword on the contribution of the university of Kent’s applied optics group to the field of fiber optics sensors

“…Operating under normal laboratory conditions the outputs of the interferometer were constantly varying due to the interferometer's sensitivity to random temperature fluctuations, air currents and acoustic noise. In order to determine the MDPS the fiber interferometer placed in a specially designed chamber to isolate the MZI from acoustic and environmental noise [1]. The MDPS achieved was 10 -5 rads/√Hz at 10 2 Hz.…”

A Synchronous Phase-Detection System for an Optical Interferometric Sensor

“…This type of modulator induces an optical phase shift by stretching the fiber resulting from an electromechanical radial displacement of the cylinder [18] . If these piezoelectric devicesare operating at frequencies well below their resonant frequency, they may be modeled as linear devices exhibiting a linear relationship between the applied voltage and the induced optical phase shift [19]. In the optics laboratory at the Naval Research Laboratory's Underwater Sound Reference Detachment in Orlando, Florida, a 5-cm-diam, PZT-A (lead zirconate-lead titanate) cylinder, with a wall 0.3-cm-thick and 5-cm-long with approximately 10 m of fiber wrapped around it, is capable of producing a phase shift (using the 6328-Ä line from a helium-neon laser) of approximately 10 rads/V.…”

Investigation of some critical aspects of on-line surface measurement by a wavelength-division-multiplexing technique

“…The fabrication of integrated circuits and MST/MEMS devices is now a mature technology in many senses, however their broad use across a number of sectors has highlighted one of the problems of micro and nano scalar manufacture namely, large region surface measurement (for form and waviness) and fast quality control in the production field [4][5][6][7][8].…”

“…The optical measurement system multiplexes two Michelson fibre interferometers with shared optical path in the main part of the optical system, one of which is used as a reference interferometer to monitor and control the high accuracy of the measurement system under environmental perturbations; the other offers remote 4 measurement with high precision in workshop environment. Spatial light-wave scanning over the surface to be measured is used to reduce the requirement of mechanic scanning that is major source of spurious signal.…”