Polarization-multiplexed and phase-stepped fiber optic shearography using laser wavelength modulation

Roger M. Groves; Stephen W. James; Ralph P. Tatam

doi:10.1117/12.357773

17 August 1999 Polarization-multiplexed and phase-stepped fiber optic shearography using laser wavelength modulation

Roger M. Groves, Stephen W. James, Ralph P. Tatam

Proceedings Volume 3745, Interferometry '99: Applications; (1999) https://doi.org/10.1117/12.357773
Event: International Conference on Optical Metrology, 1999, Pultusk Castle, Poland

Abstract

Shearography is a non-contact technique that measures deformation gradients, which can subsequently be used to evaluate out-of-plane strain components. In this paper orthogonal deformation gradients are measured quasi- simultaneously. The object under investigation is illuminated using linearly polarized light from an optical fiber. A polarization sensitive Michelson interferometer shears the speckle image from the object in orthogonal directions, for horizontally and vertically polarized light, allowing both displacement gradients to be measured independently. Laser diode injection current modulation provides a wavelength shift, which can be used to step between linear polarizations by using the birefringence of a highly-birefringent optical fiber. Wavelength modulation can also be used to phase step the interferograms produced, by using an unbalanced Michelson interferometer. If the wavelength modulation, optical fiber length and the pathlength imbalance are matched, then the polarization can be stepped between linear polarizations and the phase can be stepped by the same wavelength modulation. Images of the phase stepped correlation fringes and the wrapped phase maps illustrate the system operation.

Citation Download Citation

Roger M. Groves, Stephen W. James, and Ralph P. Tatam "Polarization-multiplexed and phase-stepped fiber optic shearography using laser wavelength modulation", Proc. SPIE 3745, Interferometry '99: Applications, (17 August 1999); https://doi.org/10.1117/12.357773

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available