Bessel beam

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

Generation of diffracted free fields and dark hollow beams using spatial filtering

Abstract: We describe the synthesis of diffraction free beams (DFB) and quasi diffraction free beams (qDFB) with features easily tunable using a holographic techniques. The hologram plate transmittance is generated by interfering two zero order Bessel beams with non-common axis. Spatial filtering techniques are implemented by controlling the kind of illumination during the reconstruction process. The experimental results are for illumination with the same kind of illumination that the recording process, obtaining a set of diffracting free beams. One of these propagates quasi-parallel to the surface hologram. For illumination with a plane wave we obtain dark hollow beam propagating in same direction that reconstruction beam. Experimental results are shown in both cases.

Using axicons for depth discrimination in excitation-emission laser scanning imaging systems

Abstract: Besides generating good approximations to zero-order Bessel beams, an axicon lens coupled to a spatial filter can be used to collect light while preserving information on the depth coordinate of the source location. To demonstrate the principle, we describe an experimental excitation-emission fluorescence imaging system that uses an axicon twice: to generate an excitation Bessel beam and to collect the emitted light.

Synchronous Imaging of Multiple Slices Using Higher-Order Bessel Beams and a Spherical Lens

Abstract: Higher-order Bessel-like optical beams can be created through off-axis coupling of light into a multimode fiber. Thanks to the aberration that is inherent in spherical surfaces, through directing the Bessel-like beam comprising multiple concentric rings onto a low-cost lens, we created multiple foci at different depths. Moreover, scanning of the optical fiber with a piezoelectric actuator in the lateral direction, we were able to acquire data from different targets located at different planes. After coupling back into the fiber, the reflected portions of light from different targets could be spatially differentiated and directed to different photo-detection units. The proposed architecture is particularly appealing for laser scanning endoscopy applications, as it does not require additional passive or active optical components for generating Bessel beams (axicons or spatial light modulators), therefore offering both miniaturized realization and high optical transmission. We’ve further demonstrated the tunability of foci separation via altering fiber-coupling conditions with tilt and translation stages. Overall, the proposed scanning method has paved the way for addressing multiple slices at single lateral scan, thus offering improved speed for imaging or ablation applications.

Diffraction of an electromagnetic vortex bessel beam by the end of a semi-infinite magnetized plasma cylinder

Abstract: Diffraction of an electromagnetic vortex Bessel beam by the end of a semi-infinite magnetized plasma cylinder located in free space is studied in the radio-frequency range. The backscattered and forward-scattered fields are represented using the eigenfunction expansion technique, and a system of integral equations for the expansion coefficients of the fields in the half-spaces on the both sides of the cylinder endface is derived and numerically solved. It is found that for the coaxial incidence of the beam on the cylinder, the forward-scattered power predominantly goes to the direction for which the tangent of the polar coordinate angle reckoned from the cylinder axis is equal to the ratio of the transverse wave number of the incident beam to its longitudinal wave number. The field scattered from the cylinder end is shown to be maximum at the surface plasmon resonance frequency of the cylinder if the topological charge of the incident beam coincides with the azimuthal index of the chosen plasmon resonance.