Dawid Borycki

A superconductor with 4-fermion attraction weakly perturbed by magnetic impurities

A superconductor with 4-fermion attraction, considered by Maćkowiak and Tarasewicz is modified by adding to the Hamiltonian a long-range magnetic interaction V between conduction fermions and localized distinguishable spin 1/2 magnetic impurities. V has the form of a reduced s-d interaction. An upper and lower bound to the system’s free energy density f(H, β) is derived and the two bounds are shown to coalesce in the thermodynamic limit. The resulting mean-field equations for the gap Δ and a parameter y, characterizing the impurity subsystem are solved and the solution minimizing f is found for various values of magnetic coupling constant g and impurity concentration. The phase diagrams of the system are depicted with five distinct phases: the normal phase, unperturbed superconducting phase, perturbed superconducting phase with nonzero gap in the excitation spectrum, perturbed gapless superconducting phase and impurity phase with completely suppressed superconductivity.

Control of the optical field coherence by spatiotemporal light modulation

The novel spatiotemporal optical coherence manipulation technique, which allows one to tailor the second-order coherence properties of a light beam, is introduced. With the use of an interferometric setup we show that the basic measure of the contrast of interference fringes, i.e., Michelsons visibility, can be controlled across the interference pattern by modulating the phase of the spectral degree of coherence.

Imaging through turbid media with wavefront modulated illumination full-field optical coherence microscopy

Imaging deep inside the tissue still remains a challenge for all microscopic techniques. Imaging using coherent illumination is even more challenging due to unwanted effects like speckle formation causing significant loss of imaging contrast. In our work we propose a solution to this problem by controlling the spatial distribution of phase of light illuminating the sample. In newly developed optical set-up the beam illuminating the sample first is passing through SLM that enables to fully control projected light patterns. The interferometric setup enables to perform 3D full field OCM imaging. We present the results from controlled wavefront illumination and its ability to image through scattering layers. The ultimate goal of our techniques is to create new imaging method applicable for biological 3D imaging in turbid medium.

Fast method of cross-talk effect reduction in biomedical imaging(Conference Presentation)

Optical imaging of biological samples or living tissue structures requires light delivery to a region of interest and then collection of scattered light or fluorescent light in order to reconstruct an image of the object. When the coherent illumination light enters bulky biological object, each of scattering center (single molecule, group of molecules or other sample feature) acts as a secondary light source. As a result, scattered spherical waves from these secondary sources interact with each other, generating cross-talk noise between optical channels (eigenmodes). The cross-talk effect have serious impact on the performance of the imaging systems. In particular it reduces an ability of optical system to transfer high spatial frequencies thereby reducing its resolution. In this work we present a fast method to eliminate all unwanted waves combination, that overlap at image plane, suppressing recovery of high spatial frequencies by using the spatio-temporal optical coherence manipulation (STOC, [1]). In this method a number of phase mask is introduced to illuminating beam by spatial light modulator in a time of single image acquisition. We use a digital mirror device (DMD) in order to rapid cross-talk noise reduction (up to 22kHz modulation frequency) when imaging living biological cells in vivo by using full-field microscopy setup with double pass arrangement. This, to our best knowledge, has never been shown before. [1] D. Borycki, M. Nowakowski, and M. Wojtkowski, Opt. Lett. 38, 4817 (2013).

Angio-OCT as a noninvasive tool for three-dimensional vascular network visualization in retinal diseases

In this paper we demonstrate applicability of intensity-based optical coherence tomography technique for noninvasive visualization of 3D retinal microcapillary network. The study was performed with ultra high resolution and high speed (180,000 Ascans/sec) spectral optical coherence tomography (SOCT). New scanning protocols and data processing algorithms have been introduced to visualize microcapillary network. Moreover, results obtained in the eyes of healthy volunteers and patients with eye diseases were compared with fluorescein angiography. Presented report shows that SOCT is well suited for visualization of 3D retinal capillary network in the healthy and pathologic eyes as well. Obtained results demonstrate high correspondence with fluorescein angiography, without using any contrast agents. Our data suggest that intensity-based SOCT has potential in the early diagnosis of the retinal vascular diseases.