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Sector Metalens for Sharp Focusing of Laser Light
2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring), 2019In this paper we have investigated a 16-sector metalens fabricated in a thin film of amorphous silicon and consisting from a set of subwavelength binary diffractive gratings. The metalens converts linearly polarized incident light into an azimuthally polarized optical vortex and focuses it. Experimentally using scanning near-field optical microscope it
S. S. Stafeev +3 more
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Sharpness-statistics-based auto-focusing algorithm for optical ptychography
Optics and Lasers in Engineering, 2020Abstract In ptychography, the precise diffraction distance is critical to recover the object with high quality. An auto-focus algorithm is proposed which consists of a rough focusing step and a fine focusing step. These two steps make the sharpness statistics for the amplitude reconstructed from a single diffraction pattern and the amplitude ...
Rui Ma +8 more
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Sharp focusing of vector optical vortices using a metalens
Journal of Optics, 2018Using an FDTD-simulation, we numerically show that a spiral metalens with topological charge m = 1, numerical aperture 1, and a focal length equal to the incident wavelength produces a tight near-surface focal spot shaped as a circle for incident TE-waves or a doughnut for TM-waves.
V V Kotlyar, A G Nalimov
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Polarization conversion at sharp focusing of vector vortex beams
2017 19th International Conference on Transparent Optical Networks (ICTON), 2017We demonstrate the conversion of cylindrically polarized laser beams in an orthogonal polarization state by introducing a high-order vortex phase singularity. Our theoretical and experimental investigations show that increasing the order of the phase singularity leads to effective generation of azimuthal polarization from radial polarization.
Svetlana Khonina, Dmitry Savelyev
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Sharp focusing of laser beams in anisotropic uniaxial crystals
Journal of Optical Technology, 2015This paper discusses the sharp focusing of homogeneously polarized laser beams in a uniaxial crystal. It is shown analytically and numerically that, when homogeneously polarized radiation is sharply focused along the axis of a crystal, two foci are formed, corresponding to the ordinary and extraordinary rays. The introduction of a vortex phase into the
S. N. Khonina +2 more
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Extraction and transport of sharp focused electron beam
Czechoslovak Journal of Physics, 2006The characteristics of the electron beam extracted from plasma sources based on hollow cathode were investigated by using computer code Kobra3-INP. It has been used to evaluate the extraction and acceleration systems in attempt to generate an electron beam with high current, high brightness and low divergence.
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Sharp-focusing Schlieren systems for studies of flat flames
Journal of Scientific Instruments, 1962The application of sharp-focusing Schlieren systems, of the type first described by Kantrowitz and Trimpi (1950), to flat disks of non-luminous flames is discussed with the object of measuring details of the flame contour across a given plane. Such details may include local effects of introducing small probes into the flame, or the measurement of small
G Dixon-Lewis, G L Isles
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Periodically focused propagation-invariant beams with sharp central peak
Optics Communications, 2003The existence of a new class of longitudinally periodic beams with sharply defined central peak is predicted. The intensity patterns of such beams are well reproduced at the equidistant transverse planes passing through nodal focal points on the propagation axis.
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Investigation of visualization characteristics of the sharp focusing schlieren method
ICIASF 2005 RecordInternational Congress onInstrumentation in AerospaceSimulation Facilities, 2006The schlieren method is most often used in the high speed wind tunnel testing as the flow visualization technique around the airfoil models etc. It is well known that the schlieren system is unable to obtain the three dimensional information occurring at various locations along the optical path.
M. Kashitani, Y. Yamaguchi
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Focusing optical waves with a rotationally symmetric sharp-edge aperture
Optics Communications, 2018Abstract While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale.
Yanwen Hu +5 more
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