Showing papers on "Zone plate published in 2000"

Fresnal Zones in Wireless Links, Zone Plate Lenses and Antennas

Abstract: From the Publisher: The first book devoted solely to Fresnel zones in microwave/mm-wave electromagnetics, this comprehensive survey covers theory, design and practical applications. Whether you are an experienced electromagnetics specialist or a newcomer to the field, whether you need practical design guidelines or a clear and concise exposition of the fundamentals, you'll find this book invaluable. Written by an acknowledged expert, the volume includes a detailed description of the application of Fresnel zones to microwave wireless communication links as well as a comprehensive description of the state-of-the-art in newly created zone plate lens and antenna technologies. It also contains an overview of the basic electromagnetic equations for time harmonic fields, and a thorough treatment of the Fresnel-Kirchoff diffraction theory. If you are a researcher, practising engineer or student in wireless/electromagnetics, this authoritative resource will help you to understand Fresnel zones, zone plate devices and their practical uses, in particular the analysis and design of microwave communication links, Fresnel zone antennas for DBS, Fresnel zone plate lenses for radio telescopes, and conformal curvilinear zone plate antennas. The work is generously illustrated.

Compact water-window transmission X-ray microscopy.

Abstract: We demonstrate sub-100 nm resolution water-window soft X-ray full-field transmission microscopy with a compact system. The microscope operates at lambda = 3.37 nm and is based on a 100 Hz table-top regenerative debris-free droplet-target laser-plasma X-ray source in combination with normal-incidence multilayer condenser optics for sample illumination. High-spatial-resolution imaging is performed with a 7.3% efficiency nickel zone plate and a 1024 x 1024 pixel CCD detector. Images of dry test samples are recorded with exposure times of a few minutes and show features smaller than 60 nm.

Nanofabrication and diffractive optics for high-resolution x-ray applications

Abstract: Short wavelength x-ray radiation microscopy is well suited for a number of material and life science studies. The x-ray microscope (XM1) at the Advanced Light Source Synchrotron in Berkeley, California uses two diffractive Fresnel zone plate lenses. The first is a large condenser lens, which collects soft x-ray radiation from a bending magnet, focuses it, and serves as a linear monochromator. The second is the objective zone plate lens, which magnifies the image of the specimen onto a high-efficiency charge coupled device detector. The objective lens determines the numerical aperture and ultimate resolution. New objective lens zone plates with a minimum linewidth of 25 nm and excellent linewidth control have been fabricated using Berkeley Lab’s 100 keV Nanowriter electron beam lithography tool, a calixarene high-resolution negative resist, and gold electroplating. Although the condenser zone plate is less critical to the resolution of the instrument, its efficiency determines the flux on the sample and ul...

Beam combining optical element

Abstract: An optical combiner with a Fresnel lens having a Fresnel surface coated with a thin film spectrally selective reflective coating configured to reflect light within a first wavelength range, and transmit light within a second wavelength range is provided. The optical combiner also includes a covering which covers the Fresnel surface and the reflective coating to provide a generally planar surface which is substantially parallel to a similarly planar exterior surface of the Fresnel lens. The covering may take the form of an optical adhesive (or of a second Fresnel lens) with an index of refraction which substantially matches the index of refraction of the Fresnel lens.

An investigation of coded aperture imaging for small animal SPECT

Abstract: Coded apertures provide a substantial gain in detection efficiency compared with conventional collimation and are well suited to imaging small volumes. Here, the authors investigated several aspects of coded aperture design for a small animal SPECT system, including aperture/detector configuration, sampling requirements, and susceptibility to scatter. They simulated various source distributions and detection systems which included one, two, and four stationary detectors placed around the object, each with a pinhole array or a Fresnel zone plate in front of the detector. Image volumes were reconstructed using an iterative successive over-relaxation algorithm with a penalized weighted least squares cost function. Multiple pinhole arrays performed better than Fresnel zone plates in terms of reconstructed mean squared error and signal-to-noise. The authors' design goals of 1% detection efficiency can be achieved with a four-detector system with arrays of 100 pinholes per detector and the scatter fraction for a 2-cm diameter object is <5%. It is concluded that a coded aperture design shows great promise for small animal SPECT.

Lithographic patterning and confocal imaging with zone plates

Abstract: Zone-plate-array lithography (ZPAL) uses an array of zone plates, combined with an array of micromechanical mirrors or shutters, to pattern features on a substrate without a mask. In this article, we investigate the patterning characteristics of individual zone plates. We show patterns printed with pixel-dose modulation (gray scaling) and subpixel beam stepping. Using a combination of these techniques for linewidth control, edge placement, and proximity-effect correction, ZPAL can produce arbitrary patterns with features as small as the focal spot of a zone plate. We also demonstrate the use of zone plates in a confocal-microscopy mode for placing the substrate at the focus of the zone plates, and for imaging. Zone-plate-array scanning-confocal microscopy (ZPAM) could be useful for gapping and alignment in ZPAL, and possibly for wafer or mask inspection at deep ultraviolet wavelengths.

A hard x-ray scanning microprobe for fluorescence imaging and microdiffraction at the advanced photon source

Abstract: A hard x-ray scanning microprobe based on zone plate optics and undulator radiation, in the energy region from 6 to 20 keV, has reached a focal spot size (FWHM) of 0.15 μm(v)×0.6 μm(h), and a photon flux of 4×109 photons/sec/0.01%BW. Using a slit 44 meters upstream to create a virtual source, a circular beam spot of 0.15 μm in diameter can be obtained with a photon flux of one order of magnitude less. During fluorescence mapping of trace elements in a single human ovarian cell, the microprobe exhibited an imaging sensitivity for Pt (Lα line) of 80 attograms/μm2 for a count rate of 10 counts per second. The x-ray microprobe has been used to map crystallographic strain and multiquantum well thickness in micro-optoelectronic devices produced with the selective area growth technique.

Compact water-window transmission X-ray microscopy

Abstract: Summary We demonstrate sub-100 nm resolution water-window soft X-ray full-field transmission microscopy with a compact system The microscope operates at la 337 nm and is based on a 100 Hz table-top regenerative debris-free droplettarget laser-plasma X-ray source in combination with normal-incidence multilayer condenser optics for sample illumination High-spatial-resolution imaging is performed with a 73% efficiency nickel zone plate and a 1024 · 1024 pixel CCD detector Images of dry test samples are recorded with exposure times of a few minutes and show features smaller than 60 nm

Polishing pad and polisher

Abstract: A window member (11) having an intentionally designed distribution of refractive index is used, as a transparent window member in a light transmission area of a polishing pad for detecting the end point of polishing by a CMP method. This window member (11) has areas (11 a) having a high refractive index and areas (11 b) having a low refractive index in its window face. In a cross section normal to the window face, the high-refractive index areas (11 a) and the low-refractive index areas (11 b) are alternately arranged in stripes. These areas (11 a and 11 b) in the window face are in a Fresnel zone plate arrangement in which the first area (center circle) is a bright one (area having a high refractive index). A plurality of such Fresnel zone plates (F) are arrayed in a matrix in the window face of the window member (11).

X-ray condenser and x-ray apparatus

Abstract: An X-ray condenser for condensing X-rays radiated from an X-ray source to a very small condensing spot is disclosed. X-rays from the X-ray source are formed to a parallel X-ray beam by a parallel type parabolic reflection mirror. The parallel X-ray beam is made monochromatic by an analyzing crystal and condensed to the condensing spot by a zone plate. The zone plate is constructed by alternately arranging a plurality of X-ray transmitting bands and a plurality of X-ray shielding bands and can condense the parallel X-ray beam to a very small focus point.

Computational study of diffraction patterns for near-field Fresnel and Gabor zone plates

Abstract: Near-field designs of Fresnel and Gabor zone plates are computationally analyzed by using versions that allow the foci to be brought closer to the plate than in the usual far-field applications. It is found that the Fresnel plate has a dominant primary conjugate pair of foci well inside the far-field region and a more intense primary focus and smaller off-focal-plane sidelobes than the near-field Gabor systems, thus yielding a superior imaging performance.

Electron beam lithography of Fresnel zone plates using a rectilinear machine and trilayer resists

Abstract: We describe the use of a commercial e-beam lithography system (JEOL JBX-6000FS) to fabricate Fresnel zone plates for x-ray microscopy. The machine is capable of controlling the pitch of optical gratings with sub-nanometer precision, so its beam placement properties are more than adequate for zone plate fabrication. The zone plate pattern is written into a thin top layer (PMMA or Calixarene) of a trilayer resist, and transferred into thick nickel zones using reactive ion etching (RIE) followed by electroplating. Zone plates with outermost zone widths of 30 nm have exhibited efficiencies up to 10.0% at a 390 eV photon energy and with diameters in the range 80 to 120 μm. Zone plates with outer zones of 18 to 20 nm were also fabricated in thinner Ni with correspondingly lower efficiencies of 2.6%. Zone plates with outermost zone widths of 45 nm have been fabricated with larger diameters up to 160 μm. All results reported were obtained with a 50 kV system with 80 μm field deflection size; future efforts will make use of a 100 kV, 500 μm field size system.

Fabrication of thick zone plates for multi-kilovolt X-rays

Abstract: Phase zone plates for multi-kilovolt X-rays with an outermost zone width of 169-30 nm and aspect ratios up to 177 were generated by a sputtered-sliced technology The generated lenses of alternating Ni80Cr20 and SiO2 consist of 188–365 layers on borosilicate glass wires and were polished by mechanical and ion processes to a thickness of 3–4 μm without carrier foil The groove efficiency was measured at the ESRF beamline ID 21 up to 38% in first order But small parts of a zone plate show an efficiency of about 10–15%

XM-1: the high-resolution soft x-ray microscope at the Advanced Light Source

Abstract: The XM-1 soft x-ray microscope utilizes bending-magnet radiation from the Advanced Light Source in Berkeley, CA. This radiation is collected by a `large' (9 mm diameter) fresnel condenser zone plate which projects light through a pinhole and illuminates the sample. The radiation transmitted through the sample is then focused and magnified by a high-precision objective micro zone plate and recorded by a soft x-ray CCD camera. Our condenser zone plate and pinhole combination serves ad our adjustable monochromator for selecting the desired photon energy, giving us a (lambda) /(Delta) (lambda) of 700. This moderate spectral resolution allows for spectroscopic imaging with XM-1, including samples of magnetic materials with contrast provided by magnetic circular dichroism. Our user-friendly software programs allow for frequent utilization of complex image processing techniques.

Fresnel lens sheet and manufacture of the same

Abstract: PROBLEM TO BE SOLVED: To provide a fresnel lens sheet of high transmissivity where the occurrence of a ghost image due to undesired light is suppressed so that satisfactory contrast can be obtained, and to provide a method for manufacturing the fresnel lens sheet. SOLUTION: In the fresnel lens sheet, many saw-tooth fresnel lenses constituted of a fresnel lens surface 4 having the function of a convex lens and a rise surface 5 positioned between adjacent fresnel lens surfaces are arranged, and antireflection processing 7 is applied on the fresnel lens surface, and a light diffusion layer 6 or a light absorbing layer is arranged on the rise surface. The fresnel lens sheet is manufactured by applying coating liquid including particles whose average particle diameter is within the range of 1 to 50 μm and particles whose average particle diameter is within the range of 0.01 to 0.2 μm by a spin coating method, thereafter, removing the particles whose average particle diameter is within the range of 0.01 to 0.2 μm.

Advanced zone plate antenna design

Abstract: The phase-correcting Fresnel zone plate antenna has been studied extensively at microwave and millimeter-wave frequencies in the past few years, in part because it offers advantages of low weight, cost, and loss. Scores of articles have appeared describing fundamental characteristics and methods of improving the efficiency, gain, and multiple- frequency band performance. As a result of these studies, one can now optimize the design, and an optimized zone plate antenna can provide performance superior to a standard lens or paraboloid antenna, especially at millimeter wavelengths. There are many differences between performance at optical wavelengths and microwaves/millimeter-waves, and these differences are described. A new planar design with non- parallel surfaces is discussed. This configuration offers further improvement in diffraction efficiency.

Demonstration of phase contrast in scanning transmission X-ray microscopy: Comparison of images obtained at NSLS X1-A with numerical simulations

Abstract: Unlike transmission X-ray microscopy, scanning transmission X-ray microscopy (STXM), till now, does not allow phase contrast. Several method have been suggested but no proof of practical feasibility has been yet given. Here we analyze the methods based on the detection of the small beam deflection induced by the object phase gradient, by a segmented detector. It is shown that structuring the zone plate illumination potentially improves the detection. A diffractive beam profiler has been constructed to condition the beam of the NSLS X1A STXM. Recent images are shown, which, compared to numerical simulations, indicate the presence of phase contrast.

Characterization of a microfocused circularly polarized x-ray probe

Abstract: We report on the development of a circularly polarized x-ray microprobe in the intermediate energy range from 5 to 10 keV. In this experiment linearly polarized synchrotron radiation was circularly polarized by means of a Bragg-diffracting diamond phase retarder and subsequently focused down to a spot size of about 4×2 μm2 by a Fresnel zone plate. The properties of the microprobe were characterized, and the technique was applied to the two-dimensional mapping of magnetic domains in HoFe2.

The condenser-monochromator with dynamical aperture synthesis for the TXM at an undulator beamline at BESSY II

Abstract: The Gottingen transmission X-ray microscope at the low emittance electron storage ring BESSY II will use the concept of dynamical aperture synthesis [1] for the condenser-monochromator. The concept is well suited as a condenser, as it can match the undulator U41 to the TXM objective and has many other advantages, too. It can use an off-axis transmission zone plate with comparatively wide zones of low aspect ratio, which therefore can be produced with almost theoretical efficiency. It will deliver a monochromaticity of 1000 to 3000. As the numerical aperture of any existing micro objective zone plate can be matched, the achievable resolution increases to the theoretical limit. Phase contrast imaging is possible with annular phase plates of extremely small width, a fast switching from amplitude contrast to phase contrast is possible. Stereo imaging with arbitrary stereo axis will be possible without tilting the object.

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. The authors succeeded in fabricating an x-ray phase zone plate using the Micrion 9500HT FIB station, which has a 50 kV Ga{sup +} column. Circular Fresnel zones were milled in a 1.0-{micro}m-thick TaSiN film deposited on a silicon wafer. The outermost zone width of the zone plate is 170 nm at a radius of 60 {micro}m. An achieved aspect ratio was 6:1.

Zone-Plate-Array Lithography (ZPAL): Simulations for system design

Abstract: We present a simulation study which examines the use of zone plates for lithography. Zone-Plate-Array Lithography (ZPAL) is a maskless lithography scheme that uses an array of shuttered zone plates to print arbitrary patterns in resist on a substrate. We have demonstrated a working ZPAL system in the UV regime, and are pursuing further experiments with the 4.5 nm X-ray to obtain smaller feature sizes. A general numerical simulation tool, based on the Fresnel-Kirchhoff diffraction theory, has been developed. A pattern will consist of many pixels exposed independently in the resist. Various zone plate and system parameters will affect the intensity distribution at the focal plane. We present simulation results which show the effect of these parameters on both the individual spots and exposed patterns.

Fresnel zone plate with multiple layers of delay zones

Abstract: The present Fresnel zone plate is comprised of a base plate (20), and a plurality of layers or orders (21, 22, etc.) of transparent phase delay zones arranged on the base plate. The zones of each succeeding order are narrower than those of the previous order, and are thinner to provide half the delay of the previous order. The radii of the zone boundaries are defined by the boundary formula Sj(n) = ∑(bμn)/2j-1, where j = integers representing order number, n = boundary number, b = focal length, and μ = wavelength. The innermost zone boundary is boundary number 1. The phase delays introduced by the delay zones are defined by the delay formula (0.5j+k)μ, where j = integers representing order number, k = is preferably 0 but may be any integer, and μ = wavelength. For example, with 3 orders of delay zones, the first order provides a 1/2μ delay, the second order provides a 1/4μ delay, and the third order provides an 1/8μ delay. Since each succeeding order is narrower than the previous order, a combination of 7 distinct delays are provided, from 1/8μ to 7/8μ, in 1/8μ increments. The delay increments are thus fine enough to correct most of the phase differences in the waves that passed through the zone plate to produce 97.5 % of the amplitude and 95 % of the intensity of an ideal lens. Alternative embodiments include a concave zone plate (35-37), a zone plate with linear delay zones (40-42), a reflective zone plate (80-84), and a flat prism (85-87).

Tapered gradient-index media and zone plates

Abstract: Light propagation through a tapered gradient-index medium with a zone plate located at the input of the medium for non-uniform and uniform illumination is studied. Evolution of the beam half-width of the zone plate diffraction orders and an analogy with the conventional lens imaging formula are presented. A particular case is analysed.

Fresnel zone plate lens and antennas for millimeter waves: history and evolutions of developments and applications

Abstract: This paper summarized some of the growth in investigations for Fresnel zone plate lens and antennas in millimeter-wave regions.

Spectromicroscopy at the XM-1

Abstract: The XM-1 x-ray microscope was built to obtain high-resolution transmission images from a wide variety of thick (<10 micron) samples. Modeled after a conventional full-field microscope, XM-1 makes use of zone plates for the condenser and objective elements. Recent work has enabled the microscope to be used for spectroscopic imaging as well. The bandwidth of light on the sample is limited by a linear monochromator which is formed by the combination of a condenser zone plate (CZP) and a pinhole at the sample plane. This combination gives a good spectral resolution which has been measured to be λ/Δλ=700. This is high enough to be able to distinguish between different elements and even some chemical states on the same scale as the spatial resolution of the instrument which is 36 nm. The measured spectral resolution and the calculated spectral resolution will both be shown.

Development of an X-ray projection microscope using synchrotron radiation

Abstract: Projection microscopy using synchrotron radiation as a light source has been developed. The system consists of a Fresnel zone plate to produce a small point source, an aperture (pinhole), a specimen holder, and a back-illuminated CCD camera. With this system, we obtained the images of EM-grids and dried mammalian cells. The resolution was estimated to be around 1.3 μm from the intensity change of 10 to 90% in the image of the edge pattern of an EM-grid.

Diffraction type lens and optical pickup device using the same

Abstract: PROBLEM TO BE SOLVED: To focus light at two wavelengths onto the recording faces of respective optical recording media having different disk thickness while satisfying the requirement for a compact and low-cost optical pickup device without making the structure of the device complicated by separately applying zone plates having a step-like cross section having different wavelength selectivity and converging effects from each other on the top and back faces of a lens. SOLUTION: Zone plates 12A, 12B having a step-like cross section (with the step height h1, h2 of the unit step) are formed on both faces of a diffraction lens 8. The number of the steps is three. When a CD-R is recorded and reproduced, the laser beams at 780 nm wavelength (λ2) in almost parallel beams incident to the diffraction lens 8 are focused by the zone plate 12B on the face of the lens 8 in the light source side onto the recording face of the CD-R. When a DVD is recorded and reproduced, the laser beams at 634 nm wavelength (λ1) in almost parallel beams incident to the diffraction lens 8 are focused by the zone plate 12A formed on the face of the lens 8 in the disk side onto the recording face of the DVD.

A Transmissive Optics Approach for Time-Slicing the LCLS X-Ray Pulse

Abstract: This paper investigates the use of off-axis zone plate optical systems to deliver time-sliced LCLS FEL pulses to users under the 3 energy chirp scenarios elucidated by P. Emma. We present formulas for designing off-axis zone plate optical systems that achieve a given time-slice duration and intensity. The results show that it is feasible to fabricate zone-plate systems capable of providing intense spots of time-sliced 8.275 KeV photons under the scenario of a 2.0% chirp, but that it is beyond current and envisioned fabrication capabilities to create zone-plate systems of similar performance under the scenarios offering energy chirps of < 0.25%. Finally we present results of numerical calculations of the electric fields delivered to the user by an off-axis zone plate optical system producing time-slices of {le} 50 {center_dot} fs with photon densities of 200 photons/{angstrom}{sup 2} under the 2% energy chirp scenario.

A variable included angle plane grating monochromator on an undulator for spectroscopy and microscopy at the Advanced Light Source

Abstract: Page 1 of 5 A Variable-Included-Angle Plane-Grating-Monochromator on an Undulator for Spectroscopy and Microscopy at the Advanced Light Source* Tony Warwick, Daniela Cambie, Howard A. Padmore and Malcolm R. Howells Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Abstract A new beam line (beam line 11.0) at the Advanced Light Source has been designed to employ a Variable-Included-Angle Plane-Grating- Monochromator. The extended range available from a specific grating is exploited to cover energies from the carbon 1s absorption edge to the oxygen 1s absorption edge with two different gratings (150l/mm and 1200l/mm) with dispersion different by a factor of three. The phase space of a zone plate microscope can then be efficiently filled either at low or high resolution (R=2500 and R=7500). At the same time the monochromator is designed to cover the energy range from 75eV to 1500eV using the same two gratings at high resolution for spectroscopy. A deformable mirror pair will re-focus to a monochromatic spot 5 x 10 microns, matched into the acceptance of a fluorescence spectrometer. The monochromator will operate in vertically collimated light and the free choice of focussing parameter provides a guarantee of high resolution even when the power loading is high. However, we will provide a thermally engineered pre-mirror so that the high resolution requirement at low photon energy can be met without loss of efficiency. Keywords: monochromator, soft x-rays, microscope, dispersion *Presented at the 7 th International Conference on Synchrotron Radiation Instrumentation, Berlin, August 21-25 2000.