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Collinear Phase Matching For Second Harmonic Generation Using Conoscopic Interferometry, A Puri, A De
Collinear Phase Matching For Second Harmonic Generation Using Conoscopic Interferometry, A Puri, A De
Physics Faculty Publications
The problem of finding phase-matching directions in noncentrosymmetric biaxial crystals is simplified here by the use of Conoscopic interferometry. Based on vector relations for wave propagation in birefringent media and solutions to phase-matching equations, we show that phase matching directions can be located on the conoscopic interferograms and that fringe numbers for dark-isochromes can be used as a guide to find phase-matching directions for a biaxial crystal. This technique can be generalized and extended to any anisotropic crystal. We have demonstrated this method for the particular case of a biaxial KTiOPO4 crystal, where it is found to be particularly …
Phase Contrast Imaging Using Photothermally Induced Phase Transitions In Liquid Crystals, Chandra S. Yelleswarapu, Sri-Rajasekhar Kothapalli, Francisco J. Aranda, D.V.G.L.N. Rao, Yvonne Vaillancourt, Brian R. Kimball
Phase Contrast Imaging Using Photothermally Induced Phase Transitions In Liquid Crystals, Chandra S. Yelleswarapu, Sri-Rajasekhar Kothapalli, Francisco J. Aranda, D.V.G.L.N. Rao, Yvonne Vaillancourt, Brian R. Kimball
Physics Faculty Publications
Phase contrast imaging is performed for live biological species using photothermal induced birefringence in dye doped liquid crystals. Using typical 4-f configuration, when liquid crystal cell is at back focal plane of Fourier lens, low spatial frequencies at center of Fourier spectrum are intense enough to induce local liquid crystal molecules into isotropic phase, whereas high spatial frequencies on the edges are not intense enough and remain in anisotropic phase. This results in π/2 phase difference between high and low spatial frequencies. This simple, inexpensive, all-optical, user-friendly, self-adaptive phase contrast imaging technique using low-power laser offers several distinct advantages.