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Proceedings Paper

Gouy phase shift in Fourier-domain optical coherence tomography
Author(s): G. Lamouche; S. Vergnole; M. L. Dufour; B. Gauthier
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Paper Abstract

A Gouy phase shift is acquired each time a beam goes through a focal point. It is a common practice in optical coherence tomography (OCT) systems to focus the light on a sample to obtain a good transverse resolution in addition to the axial resolution provided by the coherence gating. In presence of chromatic aberration, the position of the focal point is wavelength dependent. This leads to an enhanced wavelength dependency of the Gouy phase shift for measurements performed in the focal region of the sample arm. This affects the positioning of the envelope of the interferogram and can thus have a strong impact on the axial position accuracy as measured by an OCT system using the maximum of the envelope. Chromatic aberration not only leads to a Gouy phase shift, but also to an additional wavelength-dependent term related to the transverse phase distribution over the aperture of the collecting optics. This last term brings a contribution that is of the same order as the Gouy phase shift. We demonstrated these effects in time-domain OCT in a previous paper [Lamouche et al., Optics Comm., Vol. 239, 297 (2005)]. This problem is revisited with Fourier-domain OCT by performing measurements with a swept-source OCT system. This allows to confirm that the effect observed is not interferometer dependent but purely optical in origin. It also provides a clear experimental confirmation that the effect is related to chromatic aberration. This work is of interest for OCT measurements that require accurate relative position measurements in the focal region.

Paper Details

Date Published: 18 February 2008
PDF: 8 pages
Proc. SPIE 6847, Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XII, 684726 (18 February 2008); doi: 10.1117/12.764837
Show Author Affiliations
G. Lamouche, National Research Council Canada (Canada)
S. Vergnole, National Research Council Canada (Canada)
M. L. Dufour, National Research Council Canada (Canada)
B. Gauthier, National Research Council Canada (Canada)

Published in SPIE Proceedings Vol. 6847:
Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XII
Joseph A. Izatt; James G. Fujimoto; Valery V. Tuchin, Editor(s)

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