Optical fibre coherence tomography based on Fizeau interferometer configurations

摘要

An optical fibre, Fizeau configuration Optical Coherence Tomography (OCT) system is presented in this paper. The interferometer is formed between the distal end of the sample-arm fibre and the sample itself. This ensures 'downlead insensitivity'; polarisation variation is not a problem, as it is in the standard Michelson configuration. Path-length matching is performed by a secondary, bulk-optic scanning Michelson interferometer. A standard Fizeau arrangement, based around a directional coupler, makes relatively inefficient use of the optical power and has a poor SNR compared with the Michelson configuration. In this paper, we demonstrate the use of an optical circulator to permit efficient rerouting of the light, restoring the theoretical maximum SNR to about the same value obtained for comparable Michelson systems. The use of balanced detection to further improve the SNR is also discussed.