New methods of optical coherence tomography (OCT) have been developed. OCT is a modern technique for noninvasive in vivo examination of upper layers of human skin and subcutaneous blood vessels using nonionizing radiation. The instruments described in this work use a low-power (0.2–0.4 mW) superluminescent diode. Several wavelengths can be applied simultaneously. Raster scanning and raster averaging in the interferometer sample arm increase the signal-to-noise ratio by 4–10 dB.
The application of small-angle raster scanning and averaging in the sample arm of the Michelson interferometer in optical coherence tomography (OCT) is described. Raster averaging is used to increase the signal-to-noise ratio and to reduce the speckle noise of the 2D OCT image in diagnostics of surface layers of human skin and subcutaneous blood vessels in vivo. The method allows using low-coherence source of low-power radiation and increasing the depth of human skin coherent probing up to 1.5 – 1.8 mm. The reduction of speckle noise in the obtained OCT image for the first time allowed visualisation of subcutaneous ...
Experimental methods of Optical Coherence Tomography (OCT) are applied for two-dimensional mapping of subcutaneous human blood vessels. Structural images of in vivo human finger and human palm macro vessels (0.2-1.0 mm) before and after optical clearing using the modified low power rapid scanning optical delay line are presented. Images are scanned with 12 µm minimum spatial resolution. The described modifications enable to apply low power (0.4-0.5 mW), low noise broadband near infrared light source and to obtain structural images with detection of not only reflected but also multiply scattered coherence-gated photons. The achieved transcutaneous probing depth ...
Imaging fibre bundles are widely used in image transmission systems in the visible spectral range1. Their image transmission capabilities and flexibility make them interesting for OCT endoscopy2. However, cross-talk occurring between individual fibres and multimode transmission cause deterioration of the images obtained with OCT systems. In this study, a model of light propagation in a fibre bundle is developed using the Finite Difference - Time Domain (FDTD) method in order to quantify these effects. The simulated bundle output power density distribution is compared to experimental images.
Fiber imaging bundles have been investigated for use in endoscopic optical coherence tomography (OCT) systems, to obviate the requirement for scanning components within the endoscope probe section. Images have been acquired using several optical configurations, two of which are common path in design. Configurations have been selected as having potential for miniaturization and inclusion in endoscopic-type systems, since the advantages of employing imaging bundles are most clearly seen in this type of system. The various types of bundle available are described, and the properties of the leached bundles used here are discussed in detail, with reference to their effect upon ...
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