Bessel beam

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

Optical design for generating bessel beams for micromanipulation

Abstract: The central maximum of a Bessel beam offers a "non-diffracting" focal line of light that is useful in the fields of optical trapping and micromanipulation. This paper discusses the design and performance of diffractive optics for converting a Gaussian beam into a Bessel beam. The theoretical foundation of Bessel beams will be reviewed along with their optical properties. Bessel beams provide several unique characteristics such as a large depth of field and self-reconstruction. It is well known that the depth of field of a Bessel beam is larger than that of a Gaussian beam of equivalent size. However, this comes at the expense of very little power contained within the central maximum of the Bessel beam. Optical modeling and beam propagation methods are used to analyze what effect the number of rings has on the depth of field. This is an important consideration if Bessel beams are ever to be used in the fields of optical interconnects and imaging or in the area of laser processing. Where appropriate, comparisons are made between Bessel and Gaussian beams.

50 Hz volumetric functional imaging with continuously adjustable depth of focus

Abstract: Understanding how neural circuits control behavior requires monitoring a large population of neurons with high spatial resolution and volume rate. Here we report an axicon-based Bessel beam module with continuously adjustable depth of focus (CADoF), which turns frame rate into volume rate by extending the excitation focus in axial direction while maintaining high lateral resolutions. Cost-effective and compact, this CADoF Bessel module can be easily integrated into existing two-photon fluorescence microscopes. Simply translating one of the relay lenses along its optical axis enabled continuous adjustment of the focal length. We used this module to simultaneously monitor activity of spinal projection neurons extending over 60 micron depth in larval zebrafish at 50 Hz volume rate with adjustable imaging thickness.

Acoustic tweezers for sub-MM microparticle manipulation

Abstract: This paper reports a new design of an acoustic tweezers that can trap microparticles up to 0.5 mm in diameter through a 3-dimensional energy well formed in a bulk of liquid. The acoustic tweezers is built on a 1.02 mm thick lead zirconate titanate (PZT) substrate, with symmetric sectors (pie shaped when viewed from top) of air-cavity Fresnel lens. Each of the sectors is designed to have a different focal length, so that the acoustic waves from different sectors interfere with each other such that they produce a Bessel beam zone (with negative axial radiation force) along the center line perpendicular to the transducer surface. The negative radiation force traps and holds particles. The fabricated acoustic tweezers operating at 2.07 MHz has successfully been shown to trap polyethylene microsphere from 0.3 to 0.5 mm in diameter at 5 mm away from the transducer surface, providing a way to remotely manipulate large-size microparticles without physical contact to any rigid body.

Simultaneous measurement of orbital angular momentum spectra in a turbulent atmosphere without probe beam compensation.

Abstract: In free-space optical (FSO) communications, the orbital angular momentum (OAM) multiplexing/demultiplexing of Bessel beams perturbed by atmospheric turbulence is of great significance. We used the Gerchberg-Saxton algorithm without a beacon beam to compensate for the aberrant helical phase of the Bessel beam distorted by the turbulent atmosphere. The optical vortex Dammann axicon grating was applied for the simultaneous measurement of the intensities of the demodulated spectra of the OAM modes of the Bessel beams disturbed by atmospheric turbulence. The experimental results demonstrate that the distorted phase of the Bessel beam can be compensated and the mode purity of the target OAM mode is enhanced from 0.85 to 0.92 in case of weak turbulence. Our results will improve the quality of the OAM modes of Bessel beam (de)multiplexing in FSO communication systems.