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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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TL;DR: In this paper, a zero-order Bessel beam has been used for fabrication on fused quartz by direct laser writing and reactive-ion etching, where the Bessel fields are generated by diffractive optical elements.
Abstract: Diffraction-free beams having a large depth of focus are of great merit in laser-based processes in which light-matter interaction is to occur in an extended region along the beam path. We have investigated two kinds of processes that use a diffraction-free beam known as a zero-order Bessel beam: 1) Laser-drilling metal films coated on a substrate to make pinholes therein using nanosecond laser pulses at 532 nm. Given an uneven surface of the substrate, the beam irradiation point, or the process point, would be displaced from a right position. By using the Bessel beams holes ~2 mm in diameter can be formed despite the displacement of ~2 mm or more. 2) Laser-exposing bulk glass to form modifications inside using femtosecond laser pulses at 800 nm. The pulses must be temporally stretched to save their energy from being used up because of multi-photon absorption. The Bessel pulses can modify through glasses ~3 mm thick in a width of <5 mm. We have developed a new set of formulas to calculate the Bessel fields, which are generated by diffractive optical elements. The elements are designed to convert a Gaussian beam efficiently into an approximate form of the zero-order Bessel beam and are fabricated on fused quartz by direct laser writing and reactive-ion etching.
13 citations
TL;DR: Owing to the extended interaction length along the diffraction-free propagation, higher-order Stokes components are generated in a bulk Brillouin-active medium with odd and even orders propagating in opposite directions.
Abstract: We report on an experimental investigation of stimulated Brillouin scattering pumped with a Bessel beam. Owing to the extended interaction length along the diffraction-free propagation, higher-order Stokes components are generated in a bulk Brillouin-active medium with odd and even orders propagating in opposite directions. The spatial, spectral, and temporal properties of the interacting waves are discussed.
13 citations
TL;DR: This work demonstrates theoretically that the quantization of the Bessel beam profile on annular arrays results in a field which is a sum of limited diffraction fields, and demonstrates this for a five-ring, 20-mm diameter, 2.5-MHz transducer.
12 citations
20 Oct 1992
TL;DR: In this article, a conical transducer with a weighted velocity distribution is proposed as a simple and practical way of generating a quasi-non-diffracting beam, which can create a sound field almost the same as that of the Bessel beam transducers in continuous-wave excitation.
Abstract: A conical transducer with a weighted velocity distribution is proposed as a simple and practical way of generating a quasi-non-diffracting beam. It is demonstrated theoretically that the weighted conical transducer can create a sound field almost the same as that of the Bessel beam transducer in continuous-wave excitation. In the case of short-pulse excitation, sidelobes are averaged and the pulse duration time is shorter than that of the Bessel beam transducer. It is also shown through the preliminary experiments that the weighted conical transducer has the capability of generating a narrow beam ultrasound over a long axial range. >
12 citations
TL;DR: In this paper, the third harmonic of the Nd:YAG laser has been generated in air via the four-wave mixing, and the spatial spectra of the signal were presented and analyzed.
12 citations