We report the development of a low-cost hand-held optical coherence imaging system. The proposed system is based on the principle of linear optical coherence tomography (Linear OCT), a technique which was proposed in the early 2000s as a simpler alternative to the conventional time-domain and Fourier-domain OCT. In our design, as in the traditional Michaelson interferometer, light from a broadband source is split into sample and reference beams. Unlike in a Michaelson interferometer though, upon return, a tilt is introduced to the reference beam before it is combined with the sample beam to illuminate a detector array. The resulting fringe pattern encodes information about the relative time-of-flight of photons between the sample and reference arms, which can be decoded by standard signal processing techniques to obtain depth resolved reflectivity profiles of the sample. The axial resolution and the SNR of our system was measured to be approximately 5.2 μm and 80 dB, respectively. The performance of the proposed system was compared with a standard state-of-the-art Fourier-domain low coherence interferometry (LCI) system by imaging several biological and non-biological samples. The results of this study indicate that the proposed low-cost system might be a suitable choice for applications where the imaging depth and SNR can be traded for lower cost and simpler optical design. Two potentially useful applications of the proposed imaging system could be for imaging the human tympanic membrane (TM) for diagnosing middle ear pathologies, and to visualize the sub-surface features of materials for non-destructive evaluation and quality inspection.
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