Optical Polarimetric Modalities For Biomedical Research

Author : Lukas Kontenis
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (133 download)

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Download or read book Experimental Nonlinear Polarimetric Microscopy written by Lukas Kontenis and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear optical microscopy is an imaging technique that employs nonlinear optical processes for structural visualization and characterization. The method does not require labelling and provides inherent 3D optical sectioning. It is suitable for noninvasive live sample imaging, and can be applied in disease diagnostics and for clinical use. A wealth of structural information about a specimen is contained in the polarization-resolved nonlinear signal, which stems from the nonlinear susceptibility tensor \txtchin. Information on the \txtchin tensor gives access to the sample ultrastructural properties beyond the diffraction-limited spatial resolution of the microscope. Due to the nonlinear origin of the signals more details can be obtained about the structure, compared to linear optical response; although the complexity of the \txtchin tensor measurement is also increased. Typically, reduced polarimetry methods that are specific to the studied sample have been employed in nonlinear microscopy. The first experimental demonstration of complete 2D nonlinear Stokes-Mueller polarimetric (NSMP) microscopy is presented in this thesis. The NSMP method does not require \emph{a priori} assumptions about the symmetry and the structural organization of the sample. The extraction of all 2D-observable complex-valued molecular-frame {\txtchin} tensor components is performed for the first time in second- and third-harmonic generation (SHG and THG) modalities. Biomedical application of the technique is demonstrated by recovering the SHG {\txtchitwo} tensor of wall muscle from a fruit fly larva and the THG {\txtchithree} tensor of carotenoid crystallites from the root of orange carrot. The presented microscope and the analysis techniques open new frontiers to study the ultrastructure of a wide variety of samples. The general properties of polarization-resolved SHG and THG are presented in terms of the underlying \txtchin tensor properties and useful expressions are obtained; for example, the Stokes parameters and circular anisotropy of the emitted harmonic signals are derived, and new reduced polarimetric imaging techniques are demonstrated based on these expressions. In addition, details of the design, construction and calibration of the polarimetric microscope are provided together with a copy of the NSMP analysis software. Nonlinear Stokes-Mueller polarimetric microscopy can be used for accurate and model-free characterization of the nonlinear susceptibility tensor \txtchin in combination with linear polarimetric properties (e.g.,~birefringence and the degrees of polarization) of a sample, enabling a new generation of complete nonlinear polarimetric microscopy techniques for biomedical imaging and fundamental nonlinear optics research.