Showing papers on "Zone plate published in 1991"
TL;DR: In this paper, a scanning transmission X-ray microscope with a 45 nm outer zone width and a 10% diffraction efficiency Fresnel zone plate as the probe-forming optic is presented.
249 citations
TL;DR: Focusing of and imaging with atoms by means of a spherical Fresnel zone plate has been observed for the first time and its properties are presented and compared with numerical calculations.
Abstract: Focusing of and imaging with atoms by means of a spherical Fresnel zone plate has been observed for the first time. An intense beam of metastable helium atoms with atomic de Broglie wavelength ${\ensuremath{\lambda}}_{\mathrm{dB}}$=0.5--2.5 \AA{} is passed through either a single or a double slip with dimensions in the 10-\ensuremath{\mu}m range. This transverse intensity distribution is imaged by a Fresnel zone plate, 210 \ensuremath{\mu}m in diameter and with an innermost zone diameter of 18.76 \ensuremath{\mu}m. For ${\ensuremath{\lambda}}_{\mathrm{dB}}$=1.96 \AA{} the focal length is 0.45 m. The imaging properties of the zone plate are presented and compared with numerical calculations.
148 citations
TL;DR: In this article, the performance characteristics of Fresnel zone plates are described with emphasis on applications at millimeter wavelengths, and recent results along with a summary from numerous earlier investigations are included along with the design information, efficiency, bandwidth, focal characteristics, axial intensity dependence, aberrations, and far-field pattern.
Abstract: The performance characteristics of Fresnel zone plates are described with emphasis on applications at millimeter wavelengths. Recent results are included along with a summary from numerous earlier investigations. Parameters described include design information, efficiency, bandwidth, focal characteristics, off-axis performance, axial intensity dependence, aberrations, and far-field pattern. Both transmission and reflection configurations are discussed, mostly for cases where the focal length and diameter are comparable. This type of zone plate has advantages (compared to a lens or paraboloid) of reduced loss, weight, volume, and cost, as well as simple planar construction, with similar diffraction-limited beamwidth and major sidelobe performance, but lower efficiency.
67 citations
Patent•
08 Feb 1991TL;DR: In this article, a lens/zone plate combination is used to correct the dispersion between the first and second wavelengths of light by adding a zone plate on one of the surfaces of the lens.
Abstract: Chromatic dispersion between first and second wavelenghts of light is corrected by a lens/zone plate combination. The zone plate (16) is adapted both to send most of the first wavelength light into its zeroth order and to send most of the second wavelength light into its first order and to change the focal length of the second wavelength light to coincide with the focal length of the first wavelength light. A preffered embodiment includes a zinc/selinide sulfide lens (10) having a zone plate (16) etched onto one of its surfaces. The zone plate has a multi-step phase profile (20) including four phase levels. The lens/zone plate combination is particularly adapted for use with CO2 and HeNe lasers to bring their focal lengths into coincidence.
43 citations
Patent•
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TL;DR: In this paper, a method and device for imaging an object illuminated by an X-ray beam, through a zone plate, is disclosed, in which a concave mirror with a multilayered film is disposed on a path of the Xray beam to reflect the same and collect the same onto the object.
Abstract: A method and device for imaging an object illuminated by an X-ray beam, through a zone plate, is disclosed. A concave mirror with a multilayered film is disposed on a path of the X-ray beam to reflect the same and collect the same onto the object.
37 citations
TL;DR: In this article, the first generation scanning photoemission microscope at beamline X1A at the National Synchrotron Light Source (NSLS), the X1•SPEM, was designed to use the soft x-ray undulator at the NSLS as a high brightness source to illuminate a Fresnel zone plate, thus forming a finely focused probe, ≤ 0.4 μm in size, on the specimen surface.
Abstract: We have recently completed the first generation scanning photoemission microscope at beamline X1A at the National Synchrotron Light Source (NSLS), the X1‐SPEM. The instrument is designed to use the soft x‐ray undulator at the NSLS as a high brightness source to illuminate a Fresnel zone plate, thus forming a finely focused probe, ≤0.4 μm in size, on the specimen surface. A grating monochromator selects the photon energy in the 400–800 eV range with an energy resolution of 0.8–2 eV. The flux in the zone plate focus is in the 108–109 photons/s range. A single pass cylindrical mirror analyzer (CMA) is used to record photoemission spectra, or to form an image within a fixed electron energy bandwidth as the specimen is mechanically scanned. The best one‐dimensional resolution achieved so far is 0.1 μm, as judged by the 25%–75% intensity rise across an edge. This is close to the diffraction limit of the zone plate used. Due to astigmatism introduced by the beamline optics, the two‐dimensional resolution in the plane of least confusion is presently limited to 0.4 μm. Images of a microelectronic device are presented, along with some representative spectra, to demonstrate the present capabilities. With an upgrade of the beamline optics, and a new generation of zone plates, the two‐dimensional spatial resolution in a second generation instrument is anticipated to be about 50 nm.
32 citations
10 Jul 1991
TL;DR: In this paper, the effect of adding the reflector behind the zone plate to increase the gain of the antenna was investigated, and it was found that even without the reflection, the gain was increased because of the 180 degrees phase difference between the reflection off the metal rings and the open rings.
Abstract: A moderate-gain, easily constructed millimeter-wave integrated-circuit antenna based on the Fresnel zone plate was developed. The gain and bandwidth of the antenna can be varied by adjusting the f/d ratio of the zone plate; this gives the designer some latitude in fitting particular system requirements. The effect of adding the reflector behind the zone plate to increase the gain of the antenna was investigated. It was found that, even without the reflector, the gain of the zone plate was increased because of the 180 degrees phase difference between the reflection off the metal rings and the open rings. As the dielectric constant of the substrate is increased, the performance of the zone plate without the reflector approaches that of the zone plate with the reflector. Thus, on substrates with high permittivity, such as alumina and gallium arsenide, the reflector and lambda /4 spacer may not be necessary. >
32 citations
TL;DR: This paper showed that the focusing properties of Fresnel zone plates predicted by Fraunhofer diffraction theory are incorrect except for resolution defined by the Rayleigh criterion, and showed that these results are not consistent with those derived from Fresnel diffraction theories.
Abstract: Results published previously [ J. Opt. Soc. Am.57, 610 ( 1967)] concerning the focusing properties of Fresnel zone plates were obtained by implicitly invoking the Fraunhofer approximation. A comparison of these results with those derived from Fresnel diffraction theory shows that the focusing properties of Fresnel zone plates predicted by Fraunhofer diffraction theory are incorrect except for resolution defined by the Rayleigh criterion.
26 citations
TL;DR: In this article, a planar-structure acoustic focusing lens is applied to the scanning acoustic microscope as a substitute for the conventional concave lens, composed of a number of concentric annular grooves of uniform depth formed on the radiation plane according to the theory of a Fresnel zone plate.
Abstract: A planar-structure acoustic focusing lens proposed by the authors is applied successfully to the scanning acoustic microscope as a substitute for the conventional concave lens. The lens is composed of a number of concentric annular grooves of uniform depth formed on the radiation plane according to the theory of a Fresnel zone plate. Because of the simple configuration with no spherical surface, the planar lens operating at a very high frequency can be fabricated easily using the conventional photolithographic tech nique.Good focusing capability of the lenses fabricated for operation at 100MHz and 200MHz has been demonstrated through the experimental and theoretical examinations.Images of satisfactory quality have been obtained using the scanning acoustic microscope equipped with the planar lenses.
23 citations
TL;DR: Arrays of coherent focused spots generated by writing multiple Fresnel zone plates on optically and electrically addressed modulators are demonstrated and phase modulators have a better conversion efficiency than amplitude modulators.
Abstract: We demonstrate and characterize arrays of coherent focused spots generated by writing multiple Fresnel zone plates on optically and electrically addressed modulators. The programmable parameters of the array are its size (number of generated spots) and the transmissivity and focal length of each lens. As expected, phase modulators have a better conversion efficiency than amplitude modulators do.
TL;DR: In this article, a surface relief pattern was first generated by recording in photoresist the circular fringes transmitted by a Fabry-Perot interferometer, which was then transferred to the germanium substrate by ion-beam etching.
Abstract: Blazed zone plates have been manufactured in germanium. A suitable surface relief pattern was first generated by recording in photoresist the circular fringes transmitted by a Fabry-Perot interferometer. By scanning the fringe pattern and recording a series of exposures, we were able to generate a triangular groove profile. This was then transferred to the germanium substrate by ion-beam etching. By this means, diffraction efficiencies in excess of 80% have been achieved at 10μm for zone plates working in transmission and on axis.
24 Jun 1991
TL;DR: In this paper, a theory for designing high-efficiency phase-correcting FZP (Fresnel zone plate) antennas is presented, and the optimum 3dB beamwidth of the feed pattern as a function of F/D (focal length/diameter) of the plate, the relation between the phase efficiency of the antenna and the number of subzones used in each full-wave zone, and total efficiency limits of various versions are given.
Abstract: With a family of ideal radiation patterns, the theory for designing high-efficiency phase-correcting FZP (Fresnel zone plate) antennas is presented. The optimum 3-dB beamwidth of the feed pattern as a function of F/D (focal length/diameter) of the plate, the relation between the phase efficiency of the antenna and the number of subzones used in each full-wave zone, and the total efficiency limits of various versions are given. It is found that the maximum efficiency of a practical FZP antenna is usually less than 70%. The theory has been employed in designing a four-layer experimental FZP reflector antenna, and good agreement between the theoretical expectation and the measured value is obtained. >
TL;DR: In this article, a diffraction-free, high-efficiency light beam has been generated using a specific Fresnel zone plate and a suitable convex lens, and the principle and experimental results are given.
Abstract: A diffraction-free, high-efficiency light beam has been generated using a specific Fresnel zone plate and a suitable convex lens. The principle and experimental results are given.
TL;DR: The construction and test of an x-ray phase zone plate with 0.1-microm imaging resolution and >14% diffraction efficiency is reported, which served as the focusing optic in a scanning microscope that operated in the water window, and is optimally suited for imaging wet biological specimens.
Abstract: We report the construction and test of an x-ray phase zone plate with 0.1-μm imaging resolution and >14% diffraction efficiency. The zone plate served as the focusing optic in a scanning microscope that operated in the water window, 2.5 nm < λ < 4.5 nm, and therefore is optimally suited for imaging wet biological specimens. We enhanced the efficiency of the zone plate by using germanium for the absorbing zones, so that some of the incident radiation is transmitted with the correct phase shift to interfere constructively at the focal spot. The zone plate was supported on a relatively transparent membrane, giving the microscope a high absolute throughput.
TL;DR: In this article, a scanning x-ray microscope has been built at the Daresbury synchrotron radiation source and used to obtain images at soft X-ray wavelengths (∼2-4 nm).
Abstract: A scanning x-ray microscope has been built at the Daresbury synchrotron radiation source and used to obtain images at soft x-ray wavelengths (∼2–4 nm). The focusing element of the microscope is a zone plate, fabricated by a contamination writing process developed at King's College. Zone plates with the finest zone widths, and hence theoretical resolutions, below 20 nm have been fabricated in this way. The contamination material is carbon, and as such is unsuitable for high-efficiency focusing. In order to increase the zone plate efficiency, a shadowing pattern transfer process has been developed and used to replicate contamination lines with 25 nm widths into more suitable materials.
Patent•
10 Jul 1991
TL;DR: In this paper, a zone plate for focusing microwave energy is provided comprising a plurality of reflective portions (14a-d) corresponding to zones of said zone plate, each reflective portion reflecting energy lambda/P out of phase with respect to adjacent reflective portions, where lambda is the wavelength of the energy.
Abstract: A zone plate for focusing microwave energy is provided comprising a plurality of reflective portions (14a-d) corresponding to zones of said zone plate, each reflective portion reflecting energy lambda/P out of phase with respect to adjacent reflective portions, where lambda is the wavelength of the energy. The reflective portions (14a-d) are positioned in P parallel planes (10-13) mounted on low dielectric loss sheets and separated by a distance of lambda/2P such that energy reflected from the reflective portions constructively interfere at a focus of the zone plate. Also a method and apparatus for the manufacture of such a zone plate is disclosed.
TL;DR: In this article, the diffractive elements were generated by electron-beam lithography on a Mo/C multilayer mirror obtained by means of the triode sputtering technique.
Abstract: The fabrication of linear, circular, and elliptical reflective zone plate lenses by a multistep process using microfabrication technologies is reported. The diffractive elements were generated by electron-beam lithography on a Mo/C multilayer mirror obtained by means of the triode sputtering technique. The patterns were transferred anisotropically into the multilayer mirror by reactive ion etching in a fluorinated plasma. An intermediate metallic mask made by the lift-off process was used for the transfer process. The groove depth could be monitored by following the reflectivity ofthe structure with a helium-neon laser during etching. Linear, circular (with 0.4-μm outer zones), and elliptical Fresnel zone plates (with 0.8-μ.m outer zones) were produced. Test patterns with a 50-nm top and 90-nm bottom resolution were produced. The groove profile and dimensional control were also investigated.
Patent•
26 Mar 1991
TL;DR: In this paper, a single concave aspherical multi-layered mirror condenser was used to enlarge a sample image on a two-dimensional X-ray image pickup element by using a phase zone plate.
Abstract: PURPOSE:To observe a living body with high resolution by converging X rays on the sample through a single concave aspherical multi-layered mirror condenser and enlarging a sample image on a two-dimensional X-ray image pickup element by using a phase zone plate CONSTITUTION:A plasma X-ray source consisting of a pulse laser 1 is used as a pulse X-ray source and laser light is converged on a target 5 to generate X rays from an extremely small area; and the target 5 is arranged at the 1st focus of a rotary elliptic multi-layered film reflecting mirror and the sample 13 is arranged at its 2nd focus The multi-layered film mirror makes the X rays monochromatic and one X-ray pulse excited and emitted by the pulse laser 1 is used for photon counting image pickup operation The intensity of the X rays of the pulse X-ray source is adjusted so that 25<=nmax
TL;DR: In this article, a long wavelength extension of coded aperture imaging is considered in the context of a possible application in soft X-ray microscopy, and the practical implementation of the technique is briefly discussed.
Abstract: A long wavelength extension of coded aperture imaging is considered in the context of a possible application in soft X-ray microscopy. It is shown that zone plate coded aperture imaging extends naturally to longer wavelength applications and this is demonstrated experimentally. For a given source of incoherent radiation and exposure time, it is shown that incoherent techniques produce images with a substantially greater signal-to-noise ratio than coherent holography. Incoherent holography also has substantially reduced temporal coherence requirements. The practical implementation of the technique is briefly discussed.
01 Jan 1991
TL;DR: In this paper, a general expression of the zone plate equation describing its zone registration is derived from the interference of spherical waves emited from two mutually coherent point sources, and an analytical expression of focusing efficiency in terms of zone plate thickness and x-ray refractive indices of the zones is also derived.
Abstract: Spatial resolution and focusing efficiency are two important properties of a zone plate in x-ray focusing applications. A general expression of the zone plate equation describing its zone registration is derived from the interference of spherical waves emited from two mutually coherent point sources. An analytical expression of the focusing efficiency in terms of the zone plate thickness and x-ray refractive indices of the zones is also derived. Validity condition for using this expression is considered. Thickness required for obtaining adequate focusing efficiency is calculated as a function of x-ray energy for several representative materials. The spatial resolution of a finite thickness zone plate is worse than that of an infinetly thin zone plate which is approximately equal to the smallest zone width of the zone plate. The effect of the finite thickness on the spatial resolution is considered. This manuscript has been authored under contract number W-31-109-ENG-38 with the U. S. Department of Energy. Accordingly the U. S. Government retains a non-exclusive royalty-free license to publish or reproduce the published form of this contribution or allow others todo so for U. S. Government purposes. 146 / SPIE Vol 1345 Advanced X-Ray/EUV Radiation Sources andApplications(1990)© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Patent•
04 Feb 1991TL;DR: In this article, an optical element comprising a retro-reflecting or auto-collimating transmission screen (9) having one or more lenses (6,10) and an associated means (8,11) of displacing wavelengths to different degrees and whereby to spread a reflected or transmitted image into a spectral streak.
Abstract: The invention relates to optical elements, particularly retro-reflecting, retro-imaging and optical transmission inversion elements to relay a true scale equal conjugate image of a scene. Hitherto, the image had a resolution limit set by the pitch and/or packing density of micro-optical elements to reflect or transmit ray bundles impinging on them, the number of elements within the viewing zone determining the lateral and hence depth resolution in any given direction. The object of the invention is to reduce the effect of micro-screen texture in a relatively inexpensive manner, that provides real-time systems and which can be used with fast moving objects. This objective is met by an optical element comprising a retro-reflecting or auto-collimating transmission screen (9) having one or more lenses (6,10) and an associated means (8,11) of displacing wavelengths to different degrees and whereby to spread a reflected or transmitted image into a spectral streak. The means (8,11) of displacing wavelengths may be a grating, mechanically or optically blazed, or formed from prisms, or may be a diffraction or zone plate.
TL;DR: In this paper, a method of scaling the light intensity distribution in the Fresnel region is presented, which enables a modification of the zone plate transmittance, which leads to a scale transformation of the output focal curve.
Abstract: The paper presents a method of scaling the light intensity distribution in the Fresnel region. This can be useful in the design of computer generated diffractive optical elements. In particular, the method enables a modification of the zone plate transmittance, which leads to a scale transformation of the output focal curve. The approach is useful in those cases where the focal curve to be transformed is localized in the plane parallel to that of the zone plate and the complex amplitude of the focusing element is known in an analytic form. The theoretical description is based on the similarity property of the Fourier transform. The method is demostrated by obtaining computer generated zone plates with elliptic and hyperbolic focal curves.
Patent•
20 Mar 1991
TL;DR: A microwave focussing device as mentioned in this paper consists of a pane of glass carrying a transparent patterned coating of fluorine doped tin oxide, which may be in the form of a Fresnel zone plate.
Abstract: A microwave focussing device 1 for focussing microwave signals onto a collector 7 comprises a pane of glass 2 carrying a transparent patterned coating of fluorine doped tin oxide 4, which may, for example, be in the form of a Fresnel zone plate; it provides an unobtrusive means for focussing broadcast signals from satellites or broadcasting antenna used in local television stations onto a collector.
TL;DR: Two new optical free-space collinear cross-over interconnect schemes are suggested, which uses mirrors and beam splitters, while the second uses a Fresnel zone plate and lens combination.
Abstract: Two new optical free-space collinear cross-over interconnect schemes are suggested. The first optical implementation uses mirrors and beam splitters, while the second uses a Fresnel zone plate and lens combination. Some proof-of-principle experimental results are also presented.
15 Apr 1991
TL;DR: In this article, a theoretical study on the focal field distributions of the simple Fresnel zone plate (FZP) antenna and its phase-correcting versions was performed at the University of Bradford in collaboration with Mawzones Ltd.
Abstract: With the arrival of high power direct broadcasting satellites, there is an increasing demand for low-cost, environmentally unobtrusive antennas An interesting candidate in this respect is the improved Fresnel zone plate, on which research is being carried out at the University of Bradford in collaboration with Mawzones Ltd A theoretical study on the focal field distributions of the simple Fresnel zone plate (FZP) antenna and its phase-correcting versions is reported
01 Oct 1991
TL;DR: In this article, a family of basic grids set up a complete set of solutions for mutual displacements performed by translations along the axes of the coordinate system and by rotations, where the basic grids are superimposed with themself, creating the moire pattern in the form of the spherical, equilateral hyperbolic and linear zone plates.
Abstract: There are given equations describing the basic grids, which superimposed with themself, create the moire pattern in the form of the spherical, equilateral hyperbolic, and linear zone plates. All cases are derived for mutual displacements performed by translations along the axes of the coordinate system and by rotations. A family of basic grids set up a complete set of solutions. Moire zone plates can serve as imaging elements with very long, variable focal length, and have an application in alignment in the technique of three points.
01 Oct 1991
TL;DR: In this article, the possibility of creating zone plates of different anisotropic profiles of registering on the polarizationally sensitive material of two differently polarized spherical waves is shown both theoretically and experimentally.
Abstract: The diffractive elements of the anisotropic structure can transform and separate light according to its population state. From this point of view the zone plate of an anisotropic profile is a diffractive optical element of a new type. In the present contribution the possibility of creating zone plates of different anisotropic profiles of registering on the polarizationally sensitive material of two differently polarized spherical waves is shown both theoretically and experimentally.
TL;DR: In this paper, a new kind of modulated circular zone plates is presented, whose focal curve is contained in a plane parallel to that of the zone plate, and can be described as a gentle deformation of a ring.
Abstract: In this paper a new kind of modulated circular zone plates is presented. Its focal curve is contained in a plane parallel to that of the zone plate, and can be described as a gentle deformation of a ring. The transmittance is obtained in a explicit form by encoding a suitably modulated toroidal wavefront in a hologram. Usually this encoding requires the use of digital techniques. A method for obtaining more general two-dimensional focal curves is also outlined. © 1991 Taylor & Francis Ltd.
01 Oct 1991
TL;DR: In terms of achievable spatial resolutions, the most successful optics used to date for x-ray imaging have been zone plates that can be now be made with outermost zone widths of less than 25 nm.
Abstract: In terms of achievable spatial resolutions, the most successful optics used to date for x-ray imaging have been zone plates that can be now be made with outermost zone widths of less than 25 nm. Techniques for the manufacture of these optical elements are reviewed and potential future improvements are considered. Some recent applications of zone plate optics are discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.