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Optical coherence tomography (OCT) is low temporal coherence gated cross-sectional imaging modality which is noncontact, non-invasive and in vivo technology. In conventional OCT mainly a broad-band light source is used to achieve high axial resolution which is inversely proportional to spectral bandwidth of the light source. The most preferred light source in OCT is super-luminescent diode (SLD) or a supercontinuum light source, but they are bulky and costly. In addition, use of broad band light in OCT systems require dispersion compensation system because most of biological tissues are birefringence, therefore, it further adds complexity to the system. Further, use of highly spatially coherent light leads to speckle noise which degrades the image quality. We report longitudinal spatial coherence (LSC) gated line-field optical coherence tomography (LF-OCT) of multilayer structures using partially spatially coherent monochromatic light with speckle-free and reduced crosstalk. The LSC properties of low-cost diode laser source was engineered to significantly reduce LSC length to achieve high axial-resolution. The OCT system was operated both in full-field and line-field mode and it was found that line-field version has better contrast and less crosstalk. Experimental results of LSC gated OCT of multi-layer samples both biological and industrial objects along with speckle contrast, interferometric fringe contrast and LSC length measurement will be presented. The use of a low-cost diode laser in the wavelength range 800 nm for high resolution OCT is important for many biological applications. In addition, the system does not require a dispersion compensation mechanism. |
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