Citation:
P. Casaubieilh, H. D. Ford, S. W. James and R. P. Tatam. Optical coherence tomography with a Fizeau interferometer configuration. Proceedings of the SPIE Nano- and Micro-Metrology, 16-17 June 2005, Munich, Germany. Volume 5858, 58580I. Eds. Heidi Ottevaere, Peter DeWolf, Diederik S. Wiersma
Abstract:
We report the investigation of a Fizeau interferometer-based OCT system. A
secondary processing interferometer is necessary in this configuration, to
compensate the optical path difference formed in the Fizeau interferometer
between the end of the fibre and the sample. The Fizeau configuration has the
advantage of 'downlead insensitivity', which eliminates polarisation fading. An
optical circulator is used in our system to route light efficiently from the
source to the sample, and backscattered light from the sample and the fibre end
through to the Mach-Zehnder processing interferometer. The choice of a Mach-
Zehnder processing interferometer, from which both antiphase outputs are
available, facilitates the incorporation of balanced detection, which often
results in a large improvement in the Signal-to-Noise ratio (SNR) compared with
the use of a single detector. Balanced detection comprises subtraction of the
two antiphase interferometer outputs, implying that the signal amplitude is
doubled and the noise is well reduced. It has been discerned that the SNR drops
when the refractive index variation at a boundary is small. Several OCT images
of samples (resin, resin + crystals, fibre composite) are presented.
