Topic
Bessel beam
About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.
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01 Jan 2000
TL;DR: In this paper, the authors reported on the observation of far field spatial distortions of a Bessel beam after passing through a Kerr liquid and observed a coaxial ring structure that consists of two closely spaced (1.5-3.5 mrad) sharp rings and a diffuse inner ring of smaller intensity separated by 8-9 mrad.
Abstract: We report on the observation of far field spatial distortions of a Bessel beam after passing through a Kerr liquid A coaxial ring structure has been observed to occur at some threshold power. It consists of two closely spaced (1.5-3.5 mrad) sharp rings of comparable intensity and a diffuse inner ring of smaller intensity separated by 8-9 mrad. Evolution of the far field pattern with moving the sample along the propagation path of the Bessel beam shows strong dependence of beam distortions upon the position of the sample. The phenomenon is supposed to be due to nonlinearly induced phase aberrations resulting in the distortion of angular spectrum.
7 citations
TL;DR: In this article, the T-matrix method was used to calculate the incident coefficients of expansion for the incident Bessel beam (ABB) with arbitrary angles of incidence and dimensionless frequency.
Abstract: The forward scattering from rigid spheroids and endcapped cylinders with finite length (even with a large aspect ratio) immersed in a non-viscous fluid under the illumination of an idealized zeroth-order acoustical Bessel beam (ABB) with arbitrary angles of incidence is calculated and analyzed in the implementation of the T-matrix method (TTM). Based on the present method, the incident coefficients of expansion for the incident ABB are derived and simplifying methods are proposed for the numerical accuracy and computational efficiency according to the geometrical symmetries. A home-made MATLAB software package is constructed accordingly, and then verified and validated for the ABB scattering from rigid aspherical obstacles. Several numerical examples are computed for the forward scattering from both rigid spheroids and finite cylinder, with particular emphasis on the aspect ratios, the half-cone angles of ABBs, the incident angles and the dimensionless frequencies. The rectangular patterns of target strength in the (β, θs) domain (where β is the half-cone angle of the ABB and θs is the scattered polar angle) and local/total forward scattering versus dimensionless frequency are exhibited, which could provide new insights into the physical mechanisms of Bessel beam scattering by rigid spheroids and finite cylinders. The ray diagrams in geometrical models for the scattering in the forward half-space and the optical cross-section theorem help to interpret the scattering mechanisms of ABBs. This research work may provide an alternative for the partial wave series solution under certain circumstances interacting with ABBs for complicated obstacles and benefit some related works in optics and electromagnetics.
7 citations
TL;DR: A novel lighting design in microfluidic chips is put forward in which traditional incident Gaussian beam can be modulated into quasi‐Bessel beam by a microprism and waveguide, which theoretically makes forward scattering (FS) detection less than 11° possibly.
Abstract: Light scattering detection in microfluidic chips provides an important tool to identify cancer cells without any label processes. However, forward small-angle scattering signals of cells, which are related to their sizes and morphologies, are hard to be detected accurately when scattering angle is less than 11° in microfluidic chips by traditional lighting design due to the influence of incident beam. Therefore, cell's size and morphology being the golden standard for clinical detection may lose their efficacy in recognizing cancer cells from healthy ones. In this article, a novel lighting design in microfluidic chips is put forward in which traditional incident Gaussian beam can be modulated into quasi-Bessel beam by a microprism and waveguide. The quasi-Bessel beam's advantages of nondiffraction theoretically make forward scattering (FS) detection less than 11° possibly. Our experimental results for peripheral blood lymphocytes of human beings and cultured HeLa cells show that the detection rates increase by 47.87% and 46.79%, respectively, by the novel designed microfluidic chip compared to traditional Gaussian lighting method in microfluidic chips. © 2019 International Society for Advancement of Cytometry.
7 citations
TL;DR: The non-diffracting Bessel beam and the Airy beam have been successfully demonstrated in the volumetric imaging applications with faster speed since a single 2D scan provides information in the whole volume that adopted 3D scan in a traditional laser scanning microscopy.
Abstract: The light propagation in the medium normally experiences diffraction, dispersion, and scattering. It is a century-old problem to study the light propagation as the photons may attenuate and wander. We will start from the fundamental concepts of the non-diffracting beams, and examples of the non-diffracting beams include but not limited to the Bessel beam, Airy beam, Mathieu beams. We then discuss about the biomedical applications of the non-diffracting beams with a focus on the linear and nonlinear imaging, e.g., light-sheet fluorescence microscopy, two-photon fluorescence microscopy. The non-diffracting photons may provide scattering resilient imaging as well as the fast speed in the volumetric two-photon fluorescence microscopy. The non-diffracting Bessel beam and the Airy beam have been successfully demonstrated in the volumetric imaging applications with faster speed since a single 2D scan provides information in the whole volume that adopted 3D scan in a traditional laser scanning microscopy. This is an important advancement in the imaging applications with sparse sample structures, especially in neuron imaging. Moreover, the fine axial resolution can be achieved by using the self-accelerating Airy beams or the deep learning algorithms. These additional features to the existing microscopy directly realize a great advantage over the field especially for the recording of the ultrafast neuronal activities including the calcium voltage signal imaging. Nonetheless, with the illumination of dual Bessel beams at non-identical orders, the transverse resolution can also be improved by the concept of image subtraction, which would provide clearer images in the neuronal imaging.
7 citations
15 Feb 2021
TL;DR: In this paper, the authors demonstrate optical trapping of rare earth-doped NaYF4:Er/Yb nanorods using a quasi Bessel beam (QBB) generated by positive axicon optical fiber tips.
Abstract: We demonstrate optical trapping of rare earth-doped NaYF4:Er/Yb nanorods of high aspect ratio (length 1.47 μm and diameter 140 nm) using a quasi Bessel beam (QBB) generated by positive axicon optical fiber tips. Propulsion or trapping of the nanorods is demonstrated using either single or dual fiber nano-tip geometries. The optical force exerted on the trapped nanorods, their velocities, and their positions have been analyzed. We determine the trap stiffness for a single nanorod to be 0.12 pN/μm (0.003 pN/μm) by power spectrum analysis and 0.13 pN/μm (0.015 pN/μm) by Boltzmann statistics in the direction perpendicular to (along) the fiber axes for an average optical power of 34 mW. The experiments illustrate the advantage of using a QBB for multiple nanorod trapping over a large distance of up to 30 μm.
7 citations