An Extended Analytical Model to Simulate Optical Coherence Tomography Systems with a Quasi-Stationary Optical Delay Line
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AbstractThe use of Optical Coherence Tomography (OCT) in early cancer detection is still under development. While the specificity and precision of the technique has improved, the development of affordable, portable OCT configurations is important for increased clinical access by general practitioners. To this end, a proposed microphotonic time domain (TD) OCT system is being developed, based on a liquid crystal array and a microphotonic stepped mirror structure. In order to characterize the practicality of this system and its performance compared to other optical delay line (ODL) and OCT configurations, a previously demonstrated analytical simulation model has now been extended to retrieve from the interferogram, depth profiles and reflectivities for better strata OCT definition. Based on a Michelson interferometer configuration, the model allows user definition of the broadband light source, the sample’s characteristics and the ODL configuration. User defined sample characteristics include the number, thickness and reflectivities of layers. The purpose of the forwards model was to compare the conventional moving ODL reference arms with their quasi-stationary and stationary alternatives. The primary goal of the current investigation is to determine the efficacy of the backward fitting model (BFM) that uses a genetic algorithm to iteratively optimize solutions for the layer thickness and layer reflectivities for a given simulated interferogram. The genetic algorithm does retrieve the depth and reflectance of the layers identified in the interferogram, improving in precision and accuracy with each generation. The BFM can deconvolve interferograms produced using different types of ODL, with the prospect of improving the proposed discrete-step quasistationary optical delay line functionality.