Showing papers on "Zone plate published in 2015"
TL;DR: The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1 nm resolution and produces a high numerical aperture that is limited only by its extent.
Abstract: The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilise their capability for imaging and probing biological cells, nanodevices and functional matter on the nanometer scale with chemical sensitivity. Here we demonstrate focusing a hard X-ray beam to an 8 nm focus using a volume zone plate (also referred to as a wedged multilayer Laue lens). This lens was constructed using a new deposition technique that enabled the independent control of the angle and thickness of diffracting layers to microradian and nanometer precision, respectively. This ensured that the Bragg condition is satisfied at each point along the lens, leading to a high numerical aperture that is limited only by its extent. We developed a phase-shifting interferometric method based on ptychography to characterise the lens focus. The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1 nm resolution.
91 citations
TL;DR: In this paper, a flat and ultrathin lenses based on graphene, the world's thinnest known material, were presented, and the working of the lenses and their performance in the visible and terahertz regimes were analyzed computationally.
Abstract: Flat lenses when compared to curved surface lenses have the advantages of being aberration free, and they offer a compact design necessary for a myriad of electro-optical applications. In this paper we present flat and ultrathin lenses based on graphene, the world’s thinnest known material. Monolayers and multilayers of graphene were fabricated into Fresnel zones to produce Fresnel zone plates, which utilize the reflection and transmission properties of graphene for their operation. The working of the lenses and their performance in the visible and terahertz regimes were analyzed computationally. Experimental measurements were also performed to characterize the lens in the visible regime, and a good agreement was obtained with the simulations. This work demonstrates the principle of atom-thick graphene-based lenses, with perspectives for ultracompact integration.
73 citations
TL;DR: In this paper, the authors experimentally and numerically investigate an alternative approach of creating a Fresnel zone plate (FZP) with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin transparent rubber substrate.
Abstract: A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.
72 citations
TL;DR: A method for using thin nanostructured plasmonic metasurfaces to design diffractive Fresnel zone plate lenses that focus pairs of wavelengths to a single focal point to address any superposition of the two colors at the focus of the lenses by controlling the polarization of light.
Abstract: We demonstrate experimentally and by simulations a method for using thin nanostructured plasmonic metasurfaces to design diffractive Fresnel zone plate lenses that focus pairs of wavelengths to a single focal point. The metasurfaces are made of tightly packed cross and rod shaped optical nanoantennas with strong polarization and wavelength selectivity. This selectivity allows multiplexing two different lenses with low spectral crosstalk on the same substrate and to address any superposition of the two colors at the focus of the lenses by controlling the polarization of light. This concept can open the door to use ultrathin diffractive lenses in fluorescence microscopy and in stimulated emission depletion microscopy.
69 citations
TL;DR: In this article, a compact desktop size, microscope, based on nitrogen double-stream gas puff target soft X-ray source, which emits radiation in water window spectral range at the wavelength of λ ǫ = √ n, is demonstrated.
Abstract: A compact, desktop size, microscope, based on nitrogen double-stream gas puff target soft X-ray source, which emits radiation in water window spectral range at the wavelength of λ = 288 nm, is demonstrated The microscope employs ellipsoidal grazing incidence condenser mirror for sample illumination and Fresnel zone plate objective The microscope is capable of capturing magnified images of objects with 60 nm spatial resolution and exposure time as low as a few seconds Details about the source and the microscope as well as a few examples of different applications are presented and discussed
52 citations
TL;DR: In this article, the angle of diffracting layers smoothly varies in the lens to achieve optimum diffraction efficiency across the entire pupil of the lens, which can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes.
Abstract: We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.
38 citations
TL;DR: Arrays of Fresnel zone plates fabricated on a flexible substrate, which allows for the adjustment of both the field of view and optical focus are presented, which could be integrated with electronics and have a wide range of potential applications, from medical imaging to surveillance.
Abstract: Field of view and accommodative focus are two fundamental attributes of many imaging systems, ranging from human eyes to microscopes. Here, we present arrays of Fresnel zone plates fabricated on a flexible substrate, which allows for the adjustment of both the field of view and optical focus. Such zone plates function as compact and lightweight microlenses and are fabricated using silicon nanowires. Inspired by compound eyes in nature, these microlenses are designed to point along various angles in order to capture images, offering an exceptionally wide field of view. Moreover, by flexing the substrate, the lens position can be adjusted, thus achieving axial focus scanning. An array of microlenses on a flexible substrate was incorporated into an optical system to demonstrate high resolution imaging of objects located at different axial and angular positions. These silicon based microlenses could be integrated with electronics and have a wide range of potential applications, from medical imaging to surveillance.
38 citations
TL;DR: A general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave is presented.
Abstract: We present a general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave. The algorithm uses the weak object transfer function, which incorporates arbitrary pupil functions and partially coherent illumination. The approach is extended beyond the weak object regime using an iterative algorithm. We demonstrate the method on measurements of Extreme Ultraviolet Lithography (EUV) multilayer mask defects taken in an EUV zone plate microscope with both a standard zone plate lens and a zone plate implementing Zernike phase contrast.
36 citations
TL;DR: A single-pulse laser ablation technique to write parallel surface gratings and Fresnel zone plates to record a surface grating with 820 nm periodicity and asymmetric zone plate holograms on 4.5 nm gold-coated substrates is demonstrated.
Abstract: Holography plays a significant role in applications such as data storage, light trapping, security, and biosensors. However, conventional fabrication methods remain time-consuming, costly, and complex, limiting the fabrication of holograms and their extensive use. Here, we demonstrate a single-pulse laser ablation technique to write parallel surface gratings and Fresnel zone plates. We utilized a 6 ns high-energy green laser pulse to form interference patterns to record a surface grating with 820 nm periodicity and asymmetric zone plate holograms on 4.5 nm gold-coated substrates. The holographic recording process was completed within seconds. The optical characteristics of the interference patterns have been computationally modeled, and well-ordered polychromatic diffraction was observed from the fabricated holograms. The zone plate showed a significant diffraction angle of 32° from the normal incident for the focal point. The nanosecond laser interference ablation for rapid hologram fabrication holds great potential in a vast range of optical devices.
32 citations
TL;DR: By switching the transparent and opaque zones, according to the generalized fibonacci sequences, the standard Fibonacci zone plates with two on-axis foci are extended and realize adjustable multifocal distances and the adjustable compression ratio of focal spots in different directions.
Abstract: The invention relates to a generalized Fibonacci zone plate. The generalized Fibonacci zone plate consists of a transparent medium, a light-tight metal film and an annular wave zone structure and is used for substituting an amplitude-type Fresnel zone plate formed on the basis of odd-even alternation binary sequences. Under the illumination of plane waves, the generalized Fibonacci zone plate can realize the distribution of two focal points in the axial direction, the light intensities at the two focal points are identical, and the ratio of the two focal lengths is adjustable. The generalized Fibonacci zone plate is a series of concentric annular structures, easy to process and duplicate and applicable to the fields such as an optical imaging system, biomedicine and the like.
30 citations
TL;DR: In this article, a photon sieve was used for de Broglie wave manipulation of ground-state helium atoms with an average wavelength of 0.055 nm, achieving a spot size of less than 4.5 nm.
Abstract: The manipulation of low-energy beams of neutral atoms and molecules via their de Broglie wavelength is a branch of atom optics often referred to as de Broglie matter wave optics. The application areas include fundamental quantum mechanics, atom interferometry, and the development of new microscopy instrumentation. The focusing of de Broglie matter waves with a Fresnel zone plate was used to demonstrate the first neutral helium microscopy imaging. The ultimate resolution of such a microscope is limited by the width of the outermost zone. Because a Fresnel zone plate for atoms cannot be fabricated on a substrate (the low-energy atom beams would not be able to penetrate the substrate material), this gives a fabrication determined limit for the first-order focus of around 30--50 nm. Therefore, it is important to search for alternative optical elements that enable higher resolution. Photon sieves consist of a large number of pinholes, arranged suitably relative to the Fresnel zones. The great advantages are that the width of the pinholes can be larger than the respective Fresnel zones and a free-standing pinhole is much easier to fabricate than a free-standing zone. Thus, with a photon-sieve structure applied for de Broglie matter wave manipulation, the fabrication limit for focusing is reduced to potentially around 3--5 nm. Here we present a realization of such an ``atom sieve,'' which we fabricated out of a silicon nitride (SiN) membrane, using electron-beam lithography and reactive ion etching. Our atom sieve is 178 $\ensuremath{\mu}\mathrm{m}$ in diameter and has 31 991 holes. The diameter of the holes varies from 1840 to 150 nm. Using a beam of neutral, ground-state helium atoms with an average wavelength of 0.055 nm, we demonstrate helium atom focusing down to a spot size of less than 4 $\ensuremath{\mu}\mathrm{m}$. The focus size is limited by the intrinsic velocity spread of the helium beam.
TL;DR: In this article, phase shifted linear Fresnel zone plates are presented for the first time, and the impact of the phase shifting on their diffractive and focusing properties are studied, and it is demonstrated that by shifting the phase, two parallel linear beams can be generated at the focal plane.
Abstract: Phase shifted linear Fresnel zone plates are presented for the first time. These diffractive elements are linear Fresnel zone plates in which their phase are laterally shifted. The impact of the phase shifting on their diffractive and focusing properties are studied. It is demonstrated that by shifting the phase, two parallel linear beams can be generated at the focal plane. Furthermore, as they are propagating, a non-diffractive line-shaped beam is generated at a given distance from the focus. Transverse intensity profile of the beam at different distances as well as its cross section of propagation along the optical axis clearly shows that the intensity profile of the beam is really kept unchanged as it is propagated. All results are completely verified by experiments.
TL;DR: In this article, a cross-like Fresnel zone plate was analyzed and the focusing properties of the element were compared to a classic and square Fresnel plate, and it was shown that the focusing of the elements is well corrected in comparison to square and rectangular Fresnel zones.
TL;DR: The fabrication of submicron-height sine-like relief of a trifocal diffractive zone plate using a nanoimprinting technique is studied and the effects of the pupil size as well as the wavelength-dependent behavior of the zone plate are discussed.
Abstract: The fabrication of submicron-height sine-like relief of a trifocal diffractive zone plate using a nanoimprinting technique is studied. The zone plate is intended for use in combined trifocal diffractive-refractive lenses and provides the possibility to form trifocal intraocular lenses with predetermined light intensity distribution between foci. The optical properties of the designed zone plate having the optical powers 3 D, 0, -3D in the three main diffraction orders are theoretically and experimentally investigated. The results of the theoretical investigations are in good agreement with experimental measurements. The effects of the pupil size (lens diameter) as well as the wavelength-dependent behavior of the zone plate are also discussed.
TL;DR: Multilayer zone plates can be used for holographic imaging without an order-sorting aperture to improve the quality of the holographic image.
Abstract: This article describes holographic imaging experiments using a hard X-ray multilayer zone plate (MZP) with an outermost zone width of 10 nm at a photon energy of 18 keV. An order-sorting aperture (OSA) is omitted and emulated during data analysis by a `software OSA'. Scanning transmission X-ray microscopy usually carried out in the focal plane is generalized to the holographic regime. The MZP focus is characterized by a three-plane phase-retrieval algorithm to an FWHM of 10 nm.
TL;DR: An implementation of the quasi-discrete Hankel transform where a partial transform matrix can be stored to speed up repeated wave propagations over specified distances, with reduced computational memory requirements is described.
Abstract: When calculating the focusing properties of cylindrically symmetric focusing optics, numerical wave propagation calculations can be carried out using the quasi-discrete Hankel transform (QDHT). We describe here an implementation of the QDHT where a partial transform matrix can be stored to speed up repeated wave propagations over specified distances, with reduced computational memory requirements. The accuracy of the approach is then verified by comparison with analytical results, over propagation distances with both small and large Fresnel numbers. We then demonstrate the utility of this approach for calculating the focusing properties of Fresnel zone plate optics that are commonly used for x-ray imaging applications and point to future applications of this approach.
TL;DR: The proposed method enables reduction of the effective zone period by a factor of four with two zone plate layers compared to the initial e-beam lithography exposed outermost zone period and overcomes the problem that very small zone widths with high aspect ratios have to be fabricated for high-resolution hard X-ray microscopy.
Abstract: Here we analyze the potential of a new fabrication method for high resolution zone plates with high aspect ratios based on near field stacking of frequency doubled atomic layer deposited (ALD) zone plates. The proposed method enables reduction of the effective zone period by a factor of four with two zone plate layers compared to the initial e-beam lithography exposed outermost zone period. It also overcomes the problem that very small zone widths with high aspect ratios have to be fabricated for high-resolution hard X-ray microscopy. Using rigorous coupled wave theory, we have analyzed the diffraction behavior of these near field stacked zone plates and investigated strategies to optimize fabrication parameters to compensate for separation of stacked zone plates. The calculations performed for 8 keV photon energy and effective outermost zone widths of 28 nm and 15 nm predict diffraction efficiencies ≥ 20% suggesting that such optics could find widespread practical applications.
TL;DR: In this paper, the authors developed a ray tracing simulation tool for imaging systems including a Fresnel lens with a quasi-arbitrary sidewall structure, where locally, a sidewall can freely be oriented.
Abstract: We developed a ray tracing simulation tool for imaging systems including a Fresnel lens with a quasi-arbitrary sidewall structure. One issue with Fresnel lens is that noise in the image plane can appear from rays passing through or reflected at its sidewalls. One way to reduce it is to modify the orientation of the sidewalls so that rays will not reach the image plane. To find the best sidewall orientations, we developed a method where locally, a sidewall can freely be oriented. We could then derive the best modulation scheme for each Fresnel lens sidewall. In the case of a single imaging Fresnel lens, relative parasite noise intensity could mostly be prevented. To experimentally check our method, snapshot images were taken with single Fresnel lenses and a single spherical lens. No noticeable differences in image quality could be observed using a standard C-MOS camera. However, parasite noise could experimentally be detected with a Fresnel lens prototype when using a very high-dynamic range C-MOS camera.
TL;DR: A new way to fabricate thin flat lens using laser directed patterning of carbon nanotubes-based buckypaper for producing a diffractive optical device is exploited.
Abstract: Laser directed patterning of carbon nanotubes-based buckypaper for producing a diffractive optical device is presented here. Using a laser ablation method the buckypaper was patterned into a binary Fresnel zone plate lens. Computational modelling was performed which revealed excellent focusing performance of the lens for both visible and THz radiations. SEM and Raman measurements of the lens were studied to analyse the laser–material interaction. The focusing properties of the lens were characterized and a good agreement with the simulations was achieved. Hence, we exploited a new way to fabricate thin flat lens. The one-step fabrication process is economical, convenient and has great potential for industrial scale up.
Patent•
07 Oct 2015
TL;DR: In this article, the Fresnel lens according to the present invention includes two or more sawtooth prisms in a surface thereof and is made of a cured product of a curable composition containing an epoxy compound (A).
Abstract: Provided is a Fresnel lens which has excellent heat resistance and which can covert light even from a poor-quality semiconductor light sources into uniform, high-quality light and can disperse the resulting light without lowering the central illuminance. The Fresnel lens according to the present invention includes two or more sawtooth prisms in a surface thereof and is made of a cured product of a curable composition containing an epoxy compound (A). Of the sawtooth prisms, a sawtooth prism having a longest inclined side in a cross section has a roughened surface, where the cross section is given by cutting the Fresnel lens in a plane which passes through the center of the Fresnel lens and which is perpendicular to a reference plane of the Fresnel lens.
TL;DR: A binary plate lens designed to focus spherically spreading waves onto a planar region having a nearly-uniform phase proportional to that of the target location is introduced.
Abstract: Field characterization methods using a scattering target in the absence of a point-like receiver have been well described, in which scattering is recorded by a relatively large receiver located outside the field of measurement. Unfortunately, such methods are prone to artifacts caused by averaging across the receiver surface. To avoid this problem while simultaneously increasing the gain of a received signal, the present study introduces a binary plate lens designed to focus sphericallyspreading waves onto a planar region having a nearly-uniform phase proportional to that of the target location. The lens is similar to a zone plate, but modified to produce a bi-convexlike behavior, such that it focuses both planar and spherically spreading waves. A measurement device suitable for characterizing narrowband ultrasound signals in air is designed around this lens by coupling it to a target and planar receiver. A prototype device is constructed and used to characterize the field of a highly-focused 400-kHz in-air transducer along 2 radial lines. Comparison of the measurements with numeric predictions formed from nonlinear acoustic simulation showed good relative pressure correlation, with mean differences of 10% and 12% over the center 3-dB full-width at half-maximum drop and 12% and 17% over the 6-dB drop.
TL;DR: The aspect ratio limit in polymethyl methacrylate by electron-beam lithography under 100 keV should be extremely useful for guiding further technical development in nanofabrication of high-quality Fresnel zone plates.
Abstract: For acquiring high-contrast and high-brightness images in hard-x-ray optics, Fresnel zone plates with high aspect ratios (zone height/zone width) have been constantly pursued. However, knowledge of aspect ratio limits remains limited. This work explores the achievable aspect ratio limit in polymethyl methacrylate (PMMA) by electron-beam lithography (EBL) under 100 keV, and investigates the lithographic factors for this limitation. Both Monte Carlo simulation and EBL on thick PMMA are applied to investigate the profile evolution with exposure doses over 100 nm wide dense zones. A high-resolution scanning electron microscope at low acceleration mode for charging free is applied to characterize the resultant zone profiles. It was discovered for what we believe is the first time that the primary electron-beam spreading in PMMA and the proximity effect due to extra exposure from neighboring areas could be the major causes of limiting the aspect ratio. Using the optimized lithography condition, a 100 nm zone plate with aspect ratio of 15/1 was fabricated and its focusing property was characterized at the Shanghai Synchrotron Radiation Facility. The aspect ratio limit found in this work should be extremely useful for guiding further technical development in nanofabrication of high-quality Fresnel zone plates.
TL;DR: An off-axis total external reflection zone plate is applied to wavelength-dispersive X-ray spectrometry in the range from 7.8 keV to 9.0 keV, opening the door to wide-range, ultra-fast hard X-Ray spectroscopy at free-electron lasers (FELs).
Abstract: An off-axis total external reflection zone plate is applied to wavelength-dispersive X-ray spectrometry in the range from 7.8 keV to 9.0 keV. The resolving power E/ΔE of up to 1.1 × 102, demonstrated in a synchrotron proof-of-concept experiment, competes well with existing energy-dispersive instruments in this spectral range. In conjunction with the detection efficiency of (2.2 ± 0.6)%, providing a fairly constant count rate across the 1.2 keV band, the temporal pulse elongation to no more than 1.5 × 10−15 s opens the door to wide-range, ultra-fast hard X-ray spectroscopy at free-electron lasers (FELs).
TL;DR: A conventional STXM setup has been upgraded with a second micro zone plate and aligned to confocal geometry and a discussion on prospects and limitations is presented.
Abstract: Zone-plate-based scanning transmission soft X-ray microspectroscopy (STXM) is a well established technique for high-contrast imaging of sufficiently transparent specimens (e.g. ultrathin biological tissues, polymer materials, archaeometric specimens or magnetic thin films) with spatial resolutions in the regime of 20 nm and high spectroscopic or chemical sensitivity. However, due to the relatively large depth of focus of zone plates, the resolution of STXM along the optical axis so far stays unambiguously behind for thicker X-ray transparent specimens. This challenge can be addressed by the implementation of a second zone plate in the detection pathway of the beam, resulting in a confocal arrangement. Within this paper a first proof-of-principle study for a confocal STXM (cSTXM) and an elaborate alignment procedure in transmission and fluorescence geometry are presented. Based on first confocal soft X-ray micrographs of well known specimens, the advantage and limitation of cSTXM as well as further development potentials for future applications are discussed.
TL;DR: An electron beam excitation ultra-soft X-ray add-on device for a scanning electron microscope with a reflective zone plate mulichannel spectrometer in order to analyse ultra-light elements such as Li and B.
Abstract: We have developed an electron beam excitation ultra-soft X-ray add-on device for a scanning electron microscope with a reflective zone plate mulichannel spectrometer in order to analyse ultra-light elements such as Li and B. This spectrometer has high (λ/Δλ~100) resolving power in the energy range of 45 eV - 1120 eV. Metallic Li samples were examined and fluorescence spectra successfully measured. Energy resolution of 0.49 eV was measured in the ultra-low energy range using the Al L(2,3) line at 71 eV. High sensitivity of Boron detection was demonstrated on a B(4)C sample with layer thicknesses of 1-50 nm, detecting an amount of metallic Boron as small as ~0.57 fg.
TL;DR: In this paper, a weak object transfer function (WOTF) was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects of extreme ultraviolet (EUV) lithography mask defects.
Abstract: Extreme Ultraviolet (EUV) Lithography mask defects were examined on the actinic mask imaging system, SHARP, at Lawrence Berkeley National Laboratory. A quantitative phase retrieval algorithm based on the Weak Object Transfer Function was applied to the measured through-focus aerial images to examine the amplitude and phase of the defects. The accuracy of the algorithm was demonstrated by comparing the results of measurements using a phase contrast zone plate and a standard zone plate. Using partially coherent illumination to measure frequencies that would otherwise fall outside the numerical aperture (NA), it was shown that some defects are smaller than the conventional resolution of the microscope. Programmed defects of various sizes were measured and shown to have both an amplitude and a phase component that the algorithm is able to recover.
01 Oct 2015
TL;DR: In this article, a Soret-type Fresnel zone plate (FZP) lens was used for focusing in acoustic systems and the results showed a 10 dB reduction of the first sidelobe level using the FZP with a 15% main lobe broadening.
Abstract: In situations where size, weight, and system complexity are important, Fresnel zone plate (FZP) lenses have potential advantages in acoustic systems. Numerical modeling and laboratory characterization of focusing by a Soret type FZP lens are presented in this study. Both rubber foam and resonant air cavity designs are considered for the opaque zones. This study extends previous work by examining a wider range of incident field angles. Measurements of a higher-order focus, more narrow than the primary focus but with reduced gain, are also presented that compare favorably with modeling predictions. Comparison is also made between standard diffraction theory predictions (Fourier acoustics) and finite-element, oblique wave scattering simulations for the axisymmetric FZP geometry. The latter accounts for edge effects and acoustic penetration through the lens material, and predicts a higher focal gain for oblique plane wave insonification. Finally, the directivity of an FZP lens and hydrophone combination is compared with that of an ideal pressure sensitive disk of equivalent diameter to assess gain vs. side-lobe tradeoffs. Calculations demonstrate 10 dB reduction of the first sidelobe level using the FZP with a 15% main lobe broadening.
Patent•
13 May 2015
TL;DR: An optical scanning holographic image edge extracting method based on a double-hole pupil belongs to the technical field of the Optical Scanning holographic technology as mentioned in this paper, which is simple in structure and easy to operate, has high practicability, can achieve edge extraction of clear objects and has high application value.
Abstract: An optical scanning holographic image edge extracting method based on a double-hole pupil belongs to the technical field of the optical scanning holographic technology. The method includes the following steps: 1 arranging the double-hole pupil to be that P2a (x, y)= sigma (x-x1, y-y1) to obtain a first Fresnel zone plate h1 and conduct first two-dimensional holographic scanning to obtain a hologram s1; 2 arranging the double-hole pupil to be that P2b (x, y)= sigma (x-x2, y-y2) to obtain a second Fresnel zone plate h2 and conduct second two-dimensional holographic scanning to obtain a hologram s2 to record more object high frequency information; 3 conducting Fourier transform on the holograms obtained through the two-dimensional holographic scanning, and a conjugate gradient method is introduced to conduct inverse problem solving. The method is simple in structure and easy to operate, has high practicability, can achieve edge extraction of clear objects and has high application value.
TL;DR: In this paper, the authors considered the X-ray interferometer consisting of three Fresnel zone plates with the same optical axis, which operates in the amplitude-division mode and does not impose the strong requirements on the coherence of initial radiation.
Abstract: The X-ray interferometer consisting of three Fresnel zone plates with the same optical axis is considered. The interferometer operates in the amplitude-division mode and does not impose the strong requirements on the coherence of initial radiation. The interferometer is the modification of earlier one, with the main difference that the labor-intensive to manufacture multilevel Fresnel zone plates are replaced by the ordinary bi-level ones. The longitudinally and transversely defocused modifications of interferometer were considered by the numerical simulation method.
Patent•
16 Dec 2015
TL;DR: In this paper, an axial line focusing spiral zone plate was proposed, which alternately arranged a series of discontinuous spiral light transmitting ring bands and light shielding ring bands, so that incident light passes through the ring bands in different cycles to be focused at different focal points.
Abstract: The invention discloses an axial line focusing spiral zone plate. The zone plate is formed by alternately arranging a series of discontinuous spiral light transmitting ring bands and light shielding ring bands. The coordinates of the spiral ring bands in different cycles are adjusted in a certain distributing mode, so that incident light passes through the ring bands in the different cycles to be focused at different focal points, and a hollow-column-shaped line focal point is formed. Compared with a common spiral zone plate with same numerical apertures, the size of the focal point on an optical axis is effectively lengthened; designing and manufacturing are convenient and rapid, and only a production formula of the spiral ring bands and focal distances corresponding to the cycles need to be designed according to requirements; practical application and practical popularization are easy, and particularly practical application to and practical popularization for the vacuum-ultraviolet-ray waveband to the soft-X-ray waveband are easy; the axial line focusing spiral zone plate has broad application prospects in the researching fields such as particulate control, extreme ultra-violet lithography, astronomy, microscopes and micro power systems.