Bessel beam

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

Multifocal Compressive Sensing Spectral Domain Optical Coherence Tomography Based on Bessel Beam

Abstract: We present a method CS-MB-SDOCT, which combines multifocal Bessel beam spectral-domain optical coherence tomography (MB-SDOCT) and compressive sensing (CS) to increase the imaging depth using a spectrometer with lower spectral resolution.

Optimization of Confocal Bessel Beam Light-sheet for Axonal Connectomics

Abstract: Axonal connectomics entails tracing of dense axons over large brain volumes. Here, we describe a light-sheet imaging approach using scanned Bessel beam illumination and confocal slit detection and the results of simulation-guided optimization. We evaluate the performance of our approach for axon resolution and segmentation.

Submillimeter-wave cornea phantom sensing over an extended depth of field with an axicon-generated Bessel beam

Abstract: The feasibility of a 220 - 330 GHz zero order axicon generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25-degree cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate a monotonically decreasing, band integrated, backscatter intensity for increasing radius of curvature from 7 - 11 mm, when lens reflector and optical axis are aligned. Further, for radii >= 9.5 mm, maximum signal was obtained with a 1 mm transverse displacement between lens and reflector optical axes arising from spatial correlation between main lobe and out of phase side lobes. Thickness and permittivity parameter estimation experiments were performed on an 8 mm radius of curvature, 1 mm thick fused quartz dome over a 10 mm axial span. Extracted thickness and permittivity varied by less than ~ 25 $\mu$m and 0.2 respectively after correction for superluminal velocity. Estimated water permittivity and thickness of water backed gelatin phantoms showed significantly more variation due to a time varying radius of curvature.

Low‐Cost 2D Collimation of Real‐Time Pulsed Ultrasonic Beams by X‐Wave‐Based High‐Voltage Driving of Annular Arrays

Abstract: Experimental limited-diffraction waves, based on proposals in the electromagnetic field for ideal infinite apertures (where the Bessel beam concept was already implicit), were reported for finite transverse apertures, firstly in the optic field and soon extended to an acoustic context, as the so-called X-waves. The first verification of the X-waves in acoustics was based on the sequential driving of the elements in an annular array and posterior synthesis of a limited-diffraction beam by using software composition of all the radiated patterns. This would need a complex and rather expensive multi-channel electronic instrumentation, to be extended for ultrasonic generation applicable in a strict real-time regime, as it is required for effective beam collimation in practical ultrasonic applications like non-invasive medical diagnosis by imaging or industrial inspection. In this chapter, principles and implementation details are shown for an author s proposal, by means of which an efficient and simple real-time generation of limiteddiffraction ultrasonic waves can be achieved in an impulsive regime. This is based on approaching X-wave non-diffracting solutions, by converting the complex morphology of the classical X-wave excitation signals in two-level simpler pulses (equivalent, -only for driving & vibration effects-). The pulses are optimized in amplitude & width using, as target functions, time-pulsed responses in emitting faces of all the array annuli. This approach would permit to attain efficient electronic X-beam collimation in Megahertz range, having both cost and size very reduced in the multi-channel hardware involved. A real-time ultrasonic emitting and beamforming configuration, based on the new proposal for the array electric excitations, is described in detail showing: the array elements characterization, HV driving pulses and related electronic procedure. Transient acoustic field results with good focusing pattern and large field depth are demonstrated. Our optimized results for the array excitations and the acoustic beam patterns, related to an ad-hoc designed 8-annuli array (with similar dimensions and working frequency as that proposed in the classical approach), are compared with those calculated using the exact 0-order X-wave solution. The comparison shows the viability of our proposal with only small deviations from the ideal case, which can be very acceptable for imaging.