Modulation of Non-diffracting Hermite Gaussian Beams and Nonlinear Optical Microscopy for Nanoscale Sulfur Imaging

Abstract:
“Hermite Gaussian beams are the solutions of the scalar paraxial wave equation in Cartesian coordinates. A method was developed to modulate the intensity profile of non-diffracting Hermite Gaussian (HG) beams. The original HG beams intensity profile consists of high intense corner lobes and low intense central lobes which is not ideal for structured illumination in light-field microscopy. The modulated HG beams were generated by multiplying the original HG beam’s envelope by a super-Gaussian envelope to modify the intensity profile to attain equal intensity lobes. The propagation of the original HG beam and modulated HG beam were compared to determine that the non-diffracting properties of the modulated HG beam were held.

Two-photon absorption (TPA) is a nonlinear optical process in which the absorption coefficient depends on the optical intensity. In the process of two-photon absorption, an atom makes a transition from its ground state to an excited state by the simultaneous (  1 fs) absorption of two photons. In the second project, two-photon microscopy was used to detect the root uptake and determine the biodistribution of nanoscale sulfur. Characterization of pristine, stearic acid coated, and bulk sulfur was done to determine their fluorescent signal properties. Tomatoes that were grown in nano-sulfur treated soils to enhance crop nutrition and suppress disease, were imagined under the two-photon microscope to detect the root uptake of the nanoscale sulfur.”