Autocorrelation noise free Optical Coherence Tomography using the novel concept of resonant OCT (ROCT)

Abstract

Optical Coherence Tomography OCT is a noninvasive imaging technique that takes pictures of cross sections of human body tissues with a great resolution compared to other techniques. Fourier Domain OCT method provides significant improvement of imaging speed and detection sensitivity but suffers from autocorrelation noise arising as interference signals from reflections of sample layers that tends to obscure some of sample structure details. We present in this paper a new implementation of Common Path Optical Coherence Tomography, based on a resonant structure. The structure employs a semiconductor optical amplifier SOA and uses two mirrors, one coated fiber end and the other is the sample under test. Amplified multiple reflections between the laser cavity high reflection mirror and the sample layers along with SOA gain behavior results in the reduction of autocorrelation noise. Autocorrelation noise is greatly reduced by a factor of 5 dB compared to an ordinary FDOCT system. This new structure, with the absence of autocorrelation noise that covers some of the details of the sample under test in OCT setups, is capable practically of attaining images with higher resolution.