RESUMEN
A multi-vortex system nested in a Gaussian beam forms complex paths when it propagates in a free space. We consider a configuration of vortex quadrupole and present a systematic way to control the creation and annihilation of vortex pairs using only one parameter. It is shown that three classes of quadrupole vortex beams can be identified by the number of vortex pairs created or annihilated. The beam symmetry, asymptotic behavior, and stability are analyzed. The main theoretical results are verified experimentally.
RESUMEN
Remote positioning by precise measurements of lateral displacements of laser beams at large distances is inevitably disturbed by the influence of atmospheric turbulences. Here we propose the use of optical vortices, which exhibit lower transversal variations at an experimentally validated range of 100 meters. We show the higher precision of the localization of vortex points as compared with standard centroid-based assessment of Gaussian beams. Numerical simulations and experimental measurements show further improvements by averaging of the positions of up to four secondary vortices forming a stable constellation when higher values of the topological charges are used.
RESUMEN
This paper presents an analytical model of the optical vortex scanning microscope. In this microscope the Gaussian beam with an embedded optical vortex is focused into the sample plane. Additionally, the optical vortex can be moved inside the beam, which allows fine scanning of the sample. We provide an analytical solution of the whole path of the beam in the system (within paraxial approximation)-from the vortex lens to the observation plane situated on the CCD camera. The calculations are performed step by step from one optical element to the next. We show that at each step, the expression for light complex amplitude has the same form with only four coefficients modified. We also derive a simple expression for the vortex trajectory of small vortex displacements.
RESUMEN
In the optical vortex microscopy the focused Gaussian beam with optical vortex scans a sample. An optical vortex can be introduced into a laser beam with the use of a special optical element--a vortex lens. When moving the vortex lens, the optical vortex changes its position inside the spot formed by a focused laser beam. This effect can be used as a new precise scanning technique. In this paper, we study the optical vortex behavior at the sample plane. We also estimate if the new scanning technique results in observable effects that could be used for a phase object detection.
RESUMEN
A classical Mach-Zehnder two-beam interferometer was modernized using the Wollaston compensator, which allowed obtaining a stable set of specific optical markers--optical vortices. This new interferometer setup that generated optical vortices was used to measure small angle tilt. The theoretical basis of setups behavior has been described. The value of the described setup was confirmed by practical experiments.
RESUMEN
We present some applications of the optical vortex birefringence compensator, based on the C polarization type singularities generated using two Wollaston compensators. The theory and experimental results of birefringent media properties measurements are presented. The possibility of the simultaneous measurement of both the azimuth angle and the phase retardance has been analyzed and experimentally verified.
RESUMEN
A model of the human eye with a gradient index crystalline lens is presented. The crystalline lens shape at different accommodation levels is described by a single function which is a combination of hyperbolic cosine functions and hyperbolic tangent functions. Using the experimental data published in the literature a model of the variations of the external lens shape was created. Formulae for the lens shape parameters and gradient index distribution for different accommodation levels are given.
