Showing papers on "Zone plate published in 2001"

Sharper images by focusing soft X-rays with photon sieves

Abstract: Fresnel zone plates consisting of alternating transmissive and opaque circular rings can be used to focus X-rays1. The spatial resolution that can be achieved with these devices is of the order of the width of the outermost zone and is therefore limited by the smallest structure (20–40 nm) that can be fabricated by lithography today2. Here we show that a large number of pinholes distributed appropriately over the Fresnel zones make it possible to focus soft X-rays to spot sizes smaller than the diameter of the smallest pinhole. In addition, higher orders of diffraction and secondary maxima can be suppressed by several orders of magnitude. In combination with the next generation of synchrotron light sources (free-electron lasers) these ‘photon sieves’ offer new opportunities for high-resolution X-ray microscopy and spectroscopy in physical and life sciences.

P-95: Fresnel Lenses in Rear Projection Displays

Abstract: A plastic Fresnel lens positioned just before the diffusion screen in a projection system can provide significantly superior corner illumination, enhancing overall display luminance uniformity. Fresnel lenses are also used within the light engine to collimate light through the LCD panel and focus light through the projection lens. Disadvantages include the added cost of the lenses, ghosting, printout of the Fresnel rings and moire patterns. Birefringence is important to control in polarization-sensitive applications. Without reduction of ghosting artifacts, Fresnel lenses will have limited application in text-based RP systems. Ghosting is described in some detail including how it is caused, quantified and reduced. Efforts to reduce cost and birefringence will also be discussed.

High-efficiency nickel phase zone plates with 20 nm minimum outermost zone width

Abstract: Fresnel zone plates for high-resolution imaging in the soft x-ray regime were fabricated in nickel by a trilevel process, which makes use of electron-beam lithography, reactive-ion etching, and electrodeposition. In order to improve the zone plate’s resolution, which is determined by its outermost zone width, ZEP-7000 electron-beam resist was employed. Residues, which arose during pattern transfer by reactive-ion etching, and which hindered etching in small structures, were suppressed by a cleaning procedure. For improved electrodeposition process control, a nickel electroplating bath was optimized. Zone plates with minimum outermost zone widths of 20, 25 and 30 nm were fabricated, yielding 9.2%, 16.2% and 18.0% first-order diffraction efficiency, respectively, at λ=2.4 nm.

Performance of the SRRC scanning photoelectron microscope

Abstract: A scanning photoelectron microscope has been constructed at SRRC. This SPEM system consists primarily of a Fresnel zone plate (ZP) with an order-selection aperture, a flexure scanning stage, a hemispherical electron analyzer, and sample/ZP insertion system. The flexure stage is used to scan the sample. A hemispherical analyzer with Omni V lens and a 16-channel multichannel detector (MCD) is used to collect photoelectrons. A set of 16 photoelectron images at different kinetic energies can be simultaneously acquired in one single scan. The data acquisition system is designed to collect up to 32 images concurrently, including 16 MCD signals, total electron yield and transmitted photon flux. The design and some initial test results of this SPEM station are presented and discussed. # 2001 Elsevier Science B.V. All rights reserved.

Microscopic imaging with high energy x-rays by Fourier transform holography

Abstract: Experimental results obtained with an x-ray microscope based on Fourier transform holography are discussed. The experiments were done with monochromatic x rays at an energy of 14 keV. The x-ray source was a high brilliance undulator with a small vertical source size providing a spatial coherent beam. The necessity of the increase of the spatial coherence by spatial filtering is discussed together with the generation of a smallest possible reference point source. A Fresnel zone plate was used as a beam splitter. It formed the reference point source by the first order diffracted beam. The sample to be imaged is placed close to the first order focal spot and in parallel the sample is illuminated by the zero order transmitted beam. The hologram is generated by the interference of the reference wave and the object wave at a large distance from the object. A characteristic of these holograms is that a small distance in the object plane gives rise to large fringe spacing in the hologram plane and vice versa. In ...

Diffraction-limited Microbeam with Fresnel Zone Plate Optics in Hard X-Ray Regions

Abstract: A hard X-ray microbeam with zone plate optics has been tested, and preliminary experiments on scanning microscopy have been performed. A Fresnel zone plate fabricated by the electron-beam lithography technique is used as an X-ray focusing device. The material of the zone structure is tantalum with thickness of about 1 µm, and the outermost zone width of the zone plate is 0.25 µm. A focused spot size measured by knife-edge scanning is 0.3 µm at an X-ray energy of 8 keV. Closer evaluation of the spatial resolution has been done by observing resolution test patterns in a scanning X-ray microscopy experiment, and fine patterns with a 0.2 µm-structure have been resolved.

PSF measurement of imaging detectors with an x-ray microbeam

Abstract: Point spread functions (PSF) of some kinds of x-ray imaging detectors are directly measured using x-ray microbeam. The experiment has been performed at bending magnet beamline BL20B2 and undulator beamline BL2oXU of Spring-9. The microbeam is focused using a Fresnel zone plate (FZP) with coherent illumination to 0.3micrometers (almost outermost zone width of the FZP). The imaging detectors are put at the focal plane and directly detect the microbeam. Two types of high spatial resolving detectors are tested. One is x-ray- electron conversion type with electro-magnetic lens, and spatial resolution is estimated to 0.7micrometers . The other is x-ray-visible light conversion type with optical lens and the spatial resolution is estimated to 1.0micrometers .

X-ray imaging microscopy at 25 keV with Fresnel zone plate optics

Abstract: X-ray imaging microscopy with a sputtered-sliced Fresnel zone plate (SS-FZP) has been developed at an X-ray energy of 25keV. Objects were imaged in transmission with the SS-FZP as an objective with a magnification of 10.2 times, and detected with a X-ray image sensor. The performance of the imaging microscope has been tested with a gold mesh and a resolution test pattern at an undulator beamline 47XU of SPring-8. The resolution test patterns up to 0.5mm line-and-space structures have been resolved. # 2001 Elsevier Science B.V. All rights reserved.

Fresnel lens, illumination device and display device which use the same, method for designing fresnel lens and designing device therefor

Abstract: PROBLEM TO BE SOLVED: To provide a Fresnel lens with an easy designing method in which uniform illumination light quantity can be obtained without depending on the position from the optical axis of the Fresnel lens, and to provide a display device with high display quality which uses the above Fresnel lens. SOLUTION: In the Fresnel lens 7a, prisms 23 generating higher intensity of the exiting light selected from refractive prisms and reflective prisms are disposed according to the distance from the optical axis 24 of the Fresnel lens. The apex of the prism 23 is designed corresponding to the distance from the optical axis. The Fresnel lens 7a satisfying the desired display quality is disposed in the display device.

Light emitting element, its manufacturing method, and display equipment using this

Abstract: PROBLEM TO BE SOLVED: To provide a light emitting element, which is highly efficient and has no optical leak, even if it forms multi colors, displays equipment using this, and its manufacturing method. SOLUTION: The light emitting element has an organic electroluminescence element, a diffraction grating or a zone plate, and a filter part. And, the emitted light is controlled into a predetermined angle range by penetrating or reflecting of the light, which is emitted from the light emitting layer, at the diffraction grating or the zone plate, which has been formed with a predetermined grating space. Further, by passing through the filter part, the light emitting element is created, from which the light that has different color tone or chromaticity from the light emitted from a light emitting layer, is taken out. COPYRIGHT: (C)2003,JPO

Zone plate achromatic doublets

Abstract: Zone plates as used in high resolution x-ray microscopy have focal lengths which are proportional to the x-ray energy. This means that in techniques such as elemental and chemical state mapping, which require images to be made at more than one energy, refocusing is required which can lead to loss of image registration. Using two zone plates, in a similar fashion to achromatic refractive lens doublets for visible light, it is possible to focus two x-ray energies to the same spot.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fresnel image floater

Abstract: An image projection device includes a Fresnel lens (11) positioned in an optical path of an illuminated image (10) in such a way that light from the image passes twice through the Fresnel lens (11). A first optical element may be a planar mirror (13) arranged to reflect light transmitted by said Fresnel lens (11) in a first direction back through the Fresnel lens (11) in a second direction. A second optical element may be provided for changing a path of light exiting said Fresnel lens in the second direction so that the projected image appears at a location away from the path of light from the image source to the Fresnel lens.

Diffraction type lens and optical pickup apparatus using the same

Abstract: One surface of the substrate constituting a diffraction type lens is formed with a zone plate exhibiting a smaller converging action with respect to a first wavelength λ 1 of light and a greater converging action with respect to a second wavelength λ 2 of light, whereas the other surface is formed with a zone plate exhibiting a smaller converging action with respect to the second wavelength λ 2 of light and a greater converging action with respect to the first wavelength λ 1 of light. The substrate is transparent to the first and second wavelengths λ 1 and λ 2 of light. Each of the zone plates comprises concentric gratings having a stepped cross section.

Random facet Fresnel lenses and mirrors

Abstract: Fresnel-type lenses and mirrors are designed and their performance is simulated. These lenses and mirrors employ random spac- ings between elements to minimize intense higher order diffraction terms while maintaining good overall light concentration.

X-ray zone plate fabrication using a focused ion beam

Abstract: An x-ray zone plate was fabricated using the novel approach of focused ion beam (FIB) milling. The FIB technique was developed in recent years, it has been successfully used for transmission electron microscopy (TEM) sample preparation, lithographic mask repair, and failure analysis of semiconductor devices. During FIB milling, material is removed by the physical sputtering action of ion bombardment. The sputter yield is high enough to remove a substantial amount of material, therefore FIB can perform a direct patterning with submicron accuracy. We succeeded in fabricating an x-ray phase zone plate using the Micrion 9500HT FIB station, which as a 50 kV Ga+ column. Circular Fresnel zones were milled in a 1.0-micrometer-thick TaSiN film deposited on a silicon wafer. The outermost zone width of the zone plate is 170 nm at a radius of 60 micrometer. An achieved aspect ratio was 6:1.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

X-ray microbeam with sputtered-sliced Fresnel zone plate at SPring-8 undulator beamline

Abstract: A hard X-ray microbeam created from a sputtered-sliced Fresnel zone plate has been tested at SPring-8 undulator beamline. Focusing properties are evaluated in the X-ray wavelength regions of 0.15– 1.5 A . The measured focal beam size is about 0.6 μm at an X-ray wavelength of 1.4 A . In a scanning microscopy experiment, resolution-test-patterns with 0.2 μm structure are resolved at an X-ray wavelength of 0.45 A .

Construction of a scanning transmission X-ray microscope at the undulator U-41 at BESSY II

Abstract: A new scanning transmission X-ray microscope for the soft X-ray region is under construction at the BESSY II storage ring. The radiation from the undulator U-41 is monochromatized with a monochromator consisting of a plane mirror and a plane grating with varied line density. For a high resolution image, the zone plate is scanned with a piezoelectric flexure stage. The X-ray flux in the focal spot will be of the order of 10 9 photons=s. The sample is located in air. A pn-CCD detector is used to measure the transmitted intensity. # 2001 Elsevier Science B.V. All rights reserved.

Suppression of Corrugated Boundaries in Multilayer Fresnel Zone Plate for Hard X-Ray Synchrotron Radiation Using Cylindrical Slit

Abstract: Corrugated zone roughness of a circular Cu/Al multilayer Fresnel zone plate (FZP) was successfully suppressed. Such a zone corrugation was often observed in the concentric multilayers prepared using a conventional sputtering apparatus. The zone corrugation is a consequence of the oblique component of the deposition flux (i.e. shadowing effect). We therefore set a cylindrical slit (a linear slit on the surface of a stainless steel cylindrical shield) between the target and the substrate in order to eliminate the oblique flux. As a result, the zone corrugation was not observed using a scanning ion microscope (SIM).

Diffraction-limited microbeam with Fresnel zone plate optics in hard x-ray regions

Abstract: X-ray microbeam using Fresnel zone plate as a beam focusing device has been tested at an undulator beamline of Spring-8. The zone material is tantalum with thickness of 1 micrometers , and the zone structure is fabricated by using electron beam lithography technique. The outermost zone width of the zone plate is 0.25micrometers . By utilizing a fully coherent illumination, a focused spot size near to the diffraction- limit (0.3micrometers ) has been achieved at an X-ray energy of 8 keV. The measured beam profiles shows good agreement with the theoretical profile. The measured diffraction efficiency agrees well with theoretical value within an X- ray energy region from 6 keV to 10 keV. A scanning microscopy experiment has also been performed in order to evaluate the spatial resolution. Fine structures of up to 0.2micrometers are clearly observed in the measured image. The modulation transfer function derived from the measured image is 10% at 0.2micrometers line and 0.2micrometers space.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Design and application of a zone plate monochromator for laboratory soft x-ray sources

Abstract: In this article we describe the test of a zone plate monochromator for a laboratory soft x-ray source which is a laser produced plasma on a liquid jet target. The monochromator consists of a zone plate and a pinhole. Due to the special zone plate used (condensor zone plate KZP7) the monochromator is particularly suitable for laboratory sources since it collects a relatively large solid angle in the present setup. Depending upon the diameter of the pinhole a monochromaticity of up to λ/Δλ=600 can be achieved. The usefulness of the linear monochromator was proven on the basis of a filter transmission measurement. The monochromator can be used for several applications. In particular it is suitable for time-resolved x-ray absorption spectroscopy and pump and probe experiments. The use for such investigations is discussed.

Accurate pattern registration for integrated circuit tomography

Abstract: As part of an effort to develop high resolution microtomography for engineered structures, a two-level copper integrated circuit interconnect was imaged using 1.83 keV x rays at 14 angles employing a full-field Fresnel zone plate microscope. A major requirement for high resolution microtomography is the accurate registration of the reference axes in each of the many views needed for a reconstruction. A reconstruction with 100 nm resolution would require registration accuracy of 30 nm or better. This work demonstrates that even images that have strong interference fringes can be used to obtain accurate fiducials through the use of Radon transforms. We show that we are able to locate the coordinates of the rectilinear circuit patterns to 28 nm. The procedure is validated by agreement between an x-ray parallax measurement of 1.41±0.17 μm and a measurement of 1.58±0.08 μm from a scanning electron microscope image of a cross section.

Stepped conical zone plate antenna

Abstract: The Fresnel zone plate lens was invented and developed for optical frequencies. However, fabrication difficulties at the short optical wavelengths have prevented obtain good efficiencies. At longer microwave or millimeter-wavelengths fabrication is easier and phase correcting zone plate antennas have been used to obtain good efficiencies. This paper describes a new type of phase correcting zone plate having even better efficiency, namely a diffraction efficiency of 99 percent compared to a true lens, and an overall efficiency much better than a true lens. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment is accomplished by cutting different depths in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still near and can be made for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical or tapered shape. Because the phase steps are small, the far-field antenna pattern is excellent and sidelobe-levels are very low. Analysis of typical configurations will be given, showing that phase errors are small, lower than those for an eighth-wave corrected phase zone plate.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

X-ray imaging microscope with a partial coherent illumination

Abstract: An x-ray imaging microscopy experiment was performed at the x-ray energy of 8 keV. A Fresnel zone plate (FZP) fabricated by electron-beam lithography technique was used as an objective. Material of the zone structure is tantalum. The experiment was done at the undulator beamline BL47XU of Spring-8. Undulator radiation was monochromatized by passing through a liquid nitrogen cooled Si 111 double crystal monochromator. In order to eliminate speckle-like background noise, a partial coherent illumination was introduced by using a beam diffuser consisted of graphite powder. Beam spread of the illumination with the diffuser was about 35 (mu) rad. A charge coupled device (CCD) camera coupled with a phosphor screen and a microscope objective (x 12 or x 24) was used as an image detector. Converted pixel size with the x 24 lens was 0.5micrometers . Magnification of the x-ray microscope system was set to be 7.61-13. Pitch of 0.6micrometers (0.3 micrometers line and 0.3micrometers space) pattern of the test chart was resolved, and the outermost zone structure of the same type of FZP was observed. Imaging properties are also discussed by using Hopkins optical imaging theory.

Tunable diffractive optical elements for hard x-rays

Abstract: We describe the fabrication and testing of a novel type of tunable transmission hard x-ray optics. The diffractive elements are generated by electron beam lithography and chemical wet etching of oriented silicon substrates. Structures with widths down to 100 nm and extreme aspect ratios were obtained using this method. By tilting the lenses with respect to the x-ray beam, the effective path through the phase shifting structures can be varied. This makes it possible to optimize the diffraction efficiency for a wide range of photon energies, and to obtain effective aspect ratios not accessible with untilted optics. The diffraction efficiency of a Fresnel lens was measured for various energies between 8 keV and 29 keV. Values close to the theoretical limit (approx. 35%) were obtained. The described technique provides focusing in one direction only. For two-dimensional focusing, two linear lenses with different focal lengths and orthogonal orientations can be placed along the optical axis. Depending on the coherence properties of the source, such an arrangement can improve the resolution and flux compared to a single circular zone plate. The wet etching technique is also applied to the fabrication of linear gratings with pseudo-random pitch, which will be used as one-dimensional decoherers to adapt the coherence of a synchrotron beam in a defined way. Linear gratings with uniform line density can be used as beam splitters for applications such as holography or interferometry.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Scanning hard X-ray microscope with tantalum phase zone plate at the Hyogo-BL (BL24XU) of SPring-8

Abstract: A scanning hard X-ray microscope using a phase zone plate made of tantalum as its X-ray focusing device is in operation at the Hyogo-BL (BL24XU) of SPring-8. The X-ray microbeam has a size of 0.8 μm×0.7 μm at the photon energy of 10 keV, which can make visible structures as fine as 250-nm line-and-space pattern. The photon flux density at the sample position is ∼2×10 9 phs/s/μm 2 and the gain of the phase zone plate is ∼3000. The minimum detection limits irradiated by the microbeam are evaluated to be around 10 ppm for some trace elements contained in standard reference materials of glass matrices. X-ray images obtained so far demonstrate a high feasibility of the microscope.

Characterization of the focal quality of micron-size beams from x-ray mirrors and zone plates

Abstract: With the development of high quality x-ray mirrors and x-ray zone plates, the use of micron-size x-ray beams is growing rapidly. The size of the focal spot is frequently characterized by measuring either the transmitted or fluorescence counting rate as a knife edge is scanned through the beam; the full width half maximum (FWHM) of the derivative of this scan is often quoted as the 'resolution' of the system. Many systems have been built which are claimed to have a focal spot size of 1 micrometer2 or less. Unfortunately, this parameter does not give an accurate presentation of the focal quality of the beam. We have developed a test using a pattern of microfabricated 'dots' on a silicon wafer to measure the encircled energy in an x-ray focal spot as a function of radius. Using this test, we have found that focused x-ray beams frequently have a large, low intensity flare that is not represented in the beam profile as measured by the knife edge scan method. This flare can be produced by several factors including diffuse scattering from the mirror surfaces and higher orders of a zone plate. It can cause serious errors in when calculating elemental concentrations in heterogeneous samples. In addition, for micro-XAS experiments where the energy is scanned to identify the compound at a particular point, this flare may vary as a function of energy and therefore change the XAS spectra from a small particle in a complex sample.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.