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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: In this article, the performance of a Fresnel zone plate has been tested by observing the focusing property of higher-order diffraction, and the zone material was made from 1'µm-thick tantalum and the outermost zone width was 0.25'
Abstract: The performance of a Fresnel zone plate has been tested by observing the focusing property of higher-order diffraction. The Fresnel zone plate was fabricated by the electron-beam lithography technique. The zone material was made from 1 µm-thick tantalum and the outermost zone width was 0.25 µm. The third-order focused spot size measured by the knife-edge scan method was 0.1 µm full width at half-maximum at an X-ray energy of 8 keV, which is exactly equal to one-third of the first-order focal spot size.
16 citations
Patent•
IBM1
TL;DR: In this article, a test photomask comprising a fresnel zone target (FZT) pattern was used to verify the adjustment of a precision projector illumination system of an image projection system.
Abstract: A test photomask comprising a fresnel zone target (FZT) pattern may be used to verify the adjustment of a precision projector illumination system of an image projection system. The method comprises the steps of creating the FZT pattern on a photomask, projecting a pupil diagram onto an image plane using the FZT pattern, and evaluating the pupil diagram to determine the illumination system adjustment.
16 citations
TL;DR: In this article, Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes.
Abstract: We show that Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes. The focusing process compresses the condensate by orders of magnitude despite inter-atomic repulsion. Crucially, the focusing dynamics are insensitive to quantum fluctuations of the atom cloud and largely preserve the condensates' coherence, suggesting applications in passive atom-optical elements, for example zone plate lenses that focus atomic matter waves and light at the same point to strengthen their interaction. We explore transmission zone-plate focusing of alkali atoms as a route to erasable and scalable lithography of quantum electronic components in two-dimensional electron gases embedded in semiconductor nanostructures. To do this, we calculate the density profile of a two-dimensional electron gas immediately below a patch of alkali atoms deposited on the surface of the nanostructure by zone-plate focusing. Our results reveal that surface-induced polarization of only a few thousand adsorbed atoms can locally deplete the electron gas. We show that, as a result, the focused deposition of alkali atoms by existing zone plates can create quantum electronic components on the 50 nm scale, comparable to that attainable by ion beam implantation but with minimal damage to either the nanostructure or electron gas.
16 citations
24 Mar 1982
TL;DR: In this article, the intensity distribution of a zone plate with 50 or fewer open zones was calculated and the wavelength bandpass and allowable off-axistilt for zone plates were calculated and concluded that they should produce an intense nearly diffractionlimited spot when used with suitably monochromatized synchrotron radiation.
Abstract: One method for fabricating high resolution (%.lpm) Fresnel zone plates suitable forfocusing ultrasoft (',3nm) x -rays is electron beam lithography. Present technology limitsthe device size to about 100pm. For a scanning microscope we need to produce a small focalspot free of background. This requires a central stop on the zone plate as well as acollimator to eliminate the zeroth order radiation. The apodized region is now a signifi-cant fraction of the zone plate area and the intensity in the focal plane is no longer theAiry pattern of an ideal amplitude zone plate. We have calculated the intensity distribu-tions of some feasible zone plates with 50 or fewer open zones. The results indicate thatan acceptably small fraction of the first order radiation is shifted to the higher order lobes. In addition, we have calculated the wavelength bandpass and allowable off -axistilt for zone plates and conclude that they should produce an intense nearly diffractionlimited spot when used with suitably monochromatized synchrotron radiation.IntroductionThe Fresnel zone plate is the only optical element which has thus far demonstratedsubmicron resolution with ultrasoft X- rays.(1) We are building a scanning transmissionX -ray microscope(2)which will use such a zone plate to form a submicron spot through whicha biological specimen will be mechanically scanned. For unstained wet thick specimensthe resolution may turn out to be more limited by the radiation damage than by opticalconsiderations.(3) With no post- specimen optics and efficient electronic detection ofthe transmitted radiation, the damage to the specimen is minimized.Zone plate requirementsSome of the requirements for our zone plate are shown below:Requirementresolution ti 100nmhigh bandpassgood signal :noisesmall sizePurposesurpass opticalresolutionmaximize flux frommonochromatorincrease contrastreduce scan timecompatibility with ebeam fabricationImplementationfinest zone ti 80nmfew zonesapodized zone platewith collimatorshort focal lengthThe requirement for a small overall size is a consequence of the decision to use thetechnology of electron beam lithography to make the zone plate.(4) Although finer linesand more complicated patterns than we require have been written with e beam microfabricators,our requirements on precise placing of the zones will certainly test the optics and stabil-ity of the electron column. If the finest outer zone is 70nm wide, than the average errorin the placement of this zone can not be much more than 20nm before the radiation will nolonger interfere constructively. A small pattern can also be written quickly so thatdrift is less of a problem. The final pattern should be metallized on a thin substrate;about 100nm of gold in the opaque zones provides sufficient contrast for 3nm radiation.We are hopeful that a zoneplate with overall diameter of about 50 -100pm can be made usinge beam lithography.This small size does not exact much of a penalty in light gathering ability. If thediameter of the zone plate is D, the width of the outermost zone (Sr, then at wavelength Xthe focal length is approximately given by
16 citations
TL;DR: In this article, a conical configuration plasmonic zone plate based on Fresnel zones made up of Au thin film slits is proposed for focusing in the free space with visible illumination.
Abstract: A conical configuration plasmonic zone plate based on Fresnel zones made up of Au thin film slits is proposed for focusing in the free space with visible illumination. The surface plasmons enable propagation of radiating modes to distances equal to several wavelengths of the illumination field. Through numerical simulations, the conical structure found to yield focal spot beating the diffraction barrier encountered by conventional focusing elements. The focal spot size measured as full-width at half-maximum (FWHM) is observed to be as small as 0.31 times the illumination wavelength at the focal distance of 8 wavelength. Moreover, the simple design rules make it possible to predict and control the focal distances accurately.
15 citations