Bessel beam

About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.

The Bessel-beam random access trap

Abstract: We report on the investigation of crossed-Bessel-beam and hybrid Bessel-Gauss configurations for optical trapping of microscopic particles. The non-diffractive nature of the Bessel beam removes the need for high-NA optics. Crossed beam configurations allow creating trapping volumes with small aspect ratio, in comparison to single-beam Bessel traps that create wave-guide like structures. We present numerical simulations of said geometries and present experimental data of in-situ Bessel beam forces on polystyrene beads as precursor to the realization of a random access Bessel trap.

Optical system for generating approximate non-diffracting Bessel beam by LED (Light-Emitting Diode)

Abstract: The invention discloses an optical system for generating an approximate non-diffracting Bessel beam by a LED (Light-Emitting Diode), which comprises a LED lamp bead, a LED condenser lens, a condensation cylinder, a diaphragm, a short-focus lens, a long-focus lens and an axicon which are sequentially arranged, wherein the distance between the short-focus lens and the long-focus lens is the sum of the focuses of the short-focus lens and the long-focus lens; and the centers of the LED condenser lens, the condensation cylinder, the diaphragm, the short-focus lens, the long-focus lens and the axicon are all on an optical axis The invention provides a simple, convenient and rapid method for generating the approximate non-diffracting Bessel beam by an incoherent source The optical system has practical guiding significance for research on the capture of particles, the confinement and the optical coherent tomography by the approximate non-diffracting Bessel beam generated by the incoherent source

Arbitrary shaped beam scattering from a chiral-coated conducting object with arbitrary monochromatic illumination.

Abstract: An exact semi-analytical method of calculating the scattered fields from a chiral-coated conducting object under arbitrary shaped beam illumination is developed. The scattered fields and the fields within the chiral coating are expanded in terms of appropriate spherical vector wave functions. The unknown expansion coefficients are determined by solving an infinite system of linear equations derived using the method of moments technique and the boundary conditions. For incidence of a Gaussian beam, circularly polarized wave, zero-order Bessel beam and Hertzian electric dipole radiation on a chiral-coated conducting spheroid and a chiral-coated conducting circular cylinder of finite length, the normalized differential scattering cross sections are evaluated and discussed briefly.

Diffraction and thermal effect of a Bessel-Gaussian laser for Ag nanoparticle deposition.

Abstract: Nanoparticles are known to sinter at much lower temperatures than the corresponding bulk or micro size particles. A laser-assisted sintering process is considered in this study to sinter Ag nanoparticles by dispensing Ag paste onto an indium tin oxide-coated Si substrate. The Gaussian beam of a CO2 laser source is propagated through axicon and biconvex lenses, and the resulting hollow beam is focused on the Ag paste with a hollow parabolic mirror. A Bessel-Gaussian irradiance distribution is obtained at the focal plane of the parabolic mirror due to the interference of the hollow laser cone. The Fresnel diffraction approximation is considered to determine the phasor of the laser and an analytical approach is implemented to calculate the irradiance distribution of the Bessel-Gaussian beam. This irradiance distribution is utilized as a heat source in a heat conduction model and the temperature distribution is analyzed for thin Ag films formed during the laser sintering of Ag nanoparticles. An analytical expression is obtained for the temperature distribution by solving the heat conduction equation using Fourier transform for finite media. The widths of the deposited Ag lines are predicted from the temperature profiles and the model predictions compare well with the experimental results. The isotherms are found to be geometrically noncongruent with convex and concave tips depending on the locally maximum and minimum irradiances of the Bessel-Gaussian beam, respectively. The convex and concave tips, however, appear in the same isotherm for sufficiently high substrate speed relative to the laser beam.

Effective TE-Polarized Bessel-Beam Excitation for Wireless Power Transfer Near-Field Links

Abstract: The possibility to establish a wireless link in the radiative near field at millimeter waves through Transverse Electric (TE) polarized Bessel beams is here investigated. Previous realizations of TE- polarized Bessel beams at millimeter waves are based on leaky-wave resonant cavities fed with loop antennas. Unfortunately, these feeders also excite undesired, nonnegligible Transverse Magnetic (TM) field components, thus leading to a hybrid TE polarization, rather than a pure TE polarization. In this work, we propose a radial-slot array feeding technique as an effective solution to generate almost pure TE-polarized Bessel beams in leaky-wave resonant cavities. The design is based on an effective leaky-wave approach for the characterization of the launcher. The proposed TE feeding scheme is validated with full-wave results. The study of a complete wireless power transfer scenario shows that the proposed solution significantly improves the link budget compared to previous hybrid TE- and TM-polarization cases.