Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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TL;DR: The diffusion coefficient of nanospheres in different concentrations of glycerol is measured with the 2π-DH-PSF, and the error between the measured results and theoretical value was within 10%, indicating the superior performance of 2π, double-helix point spread function in 3D localization imaging of nanoparticles.
Abstract: We propose a 2π-double-helix point spread function (2π-DH-PSF) using the Fresnel zone approach that can rotate 2π rad. When 16 Fresnel zones are used, the particles can be tracked in the axial range of 10 µm in a 100× microscopy imaging system (NA=1.4, λ=514nm). We measured the diffusion coefficient of nanospheres in different concentrations of glycerol with the 2π-DH-PSF, and the error between the measured results and theoretical value was within 10%, indicating the superior performance of 2π-DH-PSF in 3D localization imaging of nanoparticles. When combined with the defocus phase, the rotation angle can reach 4π rad, four times that of the conventional DH-PSF.
3 citations
19 Feb 2015
TL;DR: In this paper, a toric Fresnel zone lens and composite elements were fabricated using electron beam direct writing for the generation of focused ring patterns, with the toric lens out-performing the other elements in several areas such as efficiency, focal depth, and ring thickness.
Abstract: Focused ring patterns are used for many applications like corneal surgery, micro drilling, optical trapping, etc. The generation of focused ring patterns in the earlier reported cases employed many refractive optical components with different functions. As a result the optics configurations of the ring pattern generation systems are bulkier. In diffractive optics, it is possible to alter a function of an element and also integrate multiple functions in a single element. In this paper, we present the design, fabrication and evaluation of single and composite diffractive optical elements for the generation of focused ring patterns. A diffractive toric Fresnel zone lens was designed for parallel beam illumination. This element is compared with other composite diffractive elements capable of generating focused ring patterns. The toric Fresnel zone lens and composite elements were fabricated using electron beam direct writing. The fabricated elements were found to exhibit interesting properties, with the toric lens out-performing the other elements in several areas such as efficiency, focal depth, and ring thickness.
3 citations
3 citations
27 Oct 2003
TL;DR: In this paper, the 3D fabrication of 3D directional couplers, Bragg gratings, and phase-type Fresnel zone plates by use of filamentation of laser pulses in silica glass is presented.
Abstract: Fabrication of 3-D directional couplers, Bragg gratings, and phase-type Fresnel zone plates by use of filamentation of laser pulses in silica glass is presented. The fabrication and morphology of micro-holes from the rear surface of silica glass are also shown. These techniques have potential use in the integration of photonic devices and systems.
3 citations
Patent•
15 Jun 1994
TL;DR: In this article, a reflective Fresnel zone plate is proposed for concentrating microwaves into a focal point, which consists of a large number of mechanically adjustable subreflectors, each having two possible positions.
Abstract: The invention relates to a reflective Fresnel zone plate for concentrating microwaves into a focal point. The Fresnel zone plate consists of a large number of mechanically adjustable subreflectors (4) each having two possible positions. The subreflectors constitute a first set of zones (1) and a second set of zones (2), with each zone construed for optimally contributing to the concentration of the microwaves.
3 citations