We demonstrate noninvasive structural and microvascular contrast imaging of different human skin diseases in vivo using an intensity difference analysis of OCT tomograms. The high-speed swept source OCT system operates at 1310 nm with 220 kHz A-scan rate. It provides an extended focus by employing a Bessel beam. The studied lesions were two cases of dermatitis and two cases of basal cell carcinoma. The lesions show characteristic vascular patterns that are significantly different from healthy skin. In case of inflammation, vessels are dilated and perfusion is increased. In case of basal cell carcinoma, the angiogram shows a denser network of unorganized vessels with large vessels close to the skin surface. Those results indicate that assessing vascular changes yields complementary information with important insight into the metabolic demand.

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Abstract:We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of 840 nm. The results demonstrate competitive sensitivity, speed, image contrast and penetration depth when compared to conventional point scanning OCT. LPSI allows high-speed retinal imaging of function and morphology with commercially available components. We further demonstrate a method that mitigates the effect of the lateral Gaussian intensity distribution across the line focus and demonstrate and discuss the feasibility of high-speed optical angiography for visualization of the retinal microcirculation.

We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300 nm with up to 440 kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin. Decoupling the illumination from the gaussian detection increases the global sensitivity and enables dark field imaging. Dark field imaging is useful to avoid strong reflexes from the sample surface that adversely affect the sensitivity due to the limited dynamic range of high speed 8 bit acquisition cards. In addition the possibility of contrasting capillaries with high sensitivity is shown, using inter-B-scan speckle variance analysis. We demonstrate intrinsic advantages of the extended focus configuration, in particular the reduction of the phase decorrelation effect below vessels leading to improved axial vessel definition.

A parallel Frequency Domain Optical Coherence Tomography (FD-OCT) system and - to the best of our knowledge- first in vivo tomograms obtained with such system are presented. A full tomogram of 256(x) x 512(z) pixels covering a sample region of 8 mm x 3,8 mm is recorded in only 1 ms. Since the transverse as well as the depth information is obtained in parallel, the structure is free of any motion artifacts. In order to study cross talk issues for parallel illumination the transversal resolution for a thermal light source is compared to that with an SLD.