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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17 Feb 2005
TL;DR: In this paper, a solid impregnated lens which obtains a high resolution even if the positional accuracy of an optical axis direction is low is used for inspection of a rear surface of a sample.
Abstract: PROBLEM TO BE SOLVED: To provide an apparatus and a method for inspection by using a solid impregnated lens which obtains a high resolution even if the positional accuracy of an optical axis direction is low. SOLUTION: The method for inspection includes a step of irradiating an observation object of a rear surface of a sample 7 with an infrared laser beam 12 emitted from a laser beam source 1 and incident upon a diffraction lens 4 as a Bessel beam 13, detecting its reflected light 14 by a photodetector 11, and performing analysis. COPYRIGHT: (C)2005,JPO&NCIPI
5 citations
TL;DR: The plane z is divided into four zones which are shown in Fig. 1 for the case t = 0 and for t > 0, the diagram moves with velocity v = c/ cosθ in the direction of z-axis.
5 citations
5 citations
01 Jan 2022
TL;DR: By integrating active phase control and passive phase modulation to a ring array of sectorial planar transducers, quasi-Bessel AV (QB-AV) beams of arbitrary order are built by the line focus of AV fields in this paper .
Abstract: Acoustic Bessel beams are commonly used as ideal sources to study the characteristics for acoustic-vortex (AV) beams, exhibiting prosperous perspectives in contactless object manipulations and acoustic communications. However, accurate Bessel beams are difficult to construct using 2-D arrays in practical applications. By integrating active phase control and passive phase modulation to a ring array of sectorial planar transducers, quasi-Bessel AV (QB-AV) beams of arbitrary order are built by the line focus of AV fields in the current study. Based on Snell’s refraction law, a circular sawtooth lens of phase modulation is designed to converge incident waves toward the beam axis at the same deflection angle. QB-AV beams constructed by the main lobes of the sectorial sources are demonstrated by theoretical derivations, numerical simulations, and quality evaluations, while those created by the sidelobes are neglected to avoid the pressure fluctuations in the near field. Experimental measurements for AV beams of different orders coincide basically with the simulations, demonstrating that line-focused QB-AV beams can be generated along the beam axis across the pressure peak. With the increase of the topological charge, the peak pressure of the beam decreases accordingly with a reduced effective axial range. The favorable results prove that, as a special kind of diffraction sources, the adjustable QB-AV beams may enable more important biomedical applications where Bessel beams are necessary, especially for the line-focused manipulation of biological and drug particles.
5 citations
TL;DR: In this paper, a single and composite off-axis vortexes embedded in the propagation-invariant beams were studied and the influence of radial wavevector of the host beam on the evolution of an offaxis vortex to the centre of the beam (recovery distance) was reported.
5 citations