Showing papers on "Zone plate published in 2009"
TL;DR: Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces, a significant step towards 10 nm resolution and beyond.
Abstract: To extend soft x-ray microscopy to a resolution of order 10 nm or better, we developed a new nanofabrication process for Fresnel zone plate lenses. The new process, based on the double patterning technique, has enabled us to fabricate high quality gold zone plates with 12 nm outer zones. Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces. This result represents a significant step towards 10 nm resolution and beyond.
273 citations
TL;DR: It is demonstrated that under these conditions it is possible to employ high orders of diffraction for imaging, and it is believed that high-order imaging paves the way towards sub-10-nm real space x-ray imaging.
Abstract: We present an x-ray optical approach to overcome the current limitations in spatial resolution of x-ray microscopes. Our new BESSY full-field x-ray microscope operates with an energy resolution up to E/DeltaE=10(4). We demonstrate that under these conditions it is possible to employ high orders of diffraction for imaging. Using the third order of diffraction of a zone plate objective with 25 nm outermost zone width, 14 nm lines and spaces of a multilayer test structure were clearly resolved. We believe that high-order imaging paves the way towards sub-10-nm real space x-ray imaging.
127 citations
TL;DR: In simulations with objects representing isolated cells such as yeast, it is found that XDM has the potential for delivering equivalent resolution images using fewer photons, which can be an important advantage for studying radiation-sensitive biological and soft matter specimens.
Abstract: Using a signal-to-noise ratio estimation based on correlations between multiple simulated images, we compare the dose efficiency of two soft x-ray imaging systems: incoherent brightfield imaging using zone plate optics in a transmission x-ray microscope (TXM), and x-ray diffraction microscopy (XDM) where an image is reconstructed from the far-field coherent diffraction pattern. In XDM one must computationally phase weak diffraction signals; in TXM one suffers signal losses due to the finite numerical aperture and efficiency of the optics. In simulations with objects representing isolated cells such as yeast, we find that XDM has the potential for delivering equivalent resolution images using fewer photons. This can be an important advantage for studying radiation-sensitive biological and soft matter specimens.
85 citations
TL;DR: Novel hard x-ray phase imaging microscopy that simply uses an objective and a transmission grating to append a quantitative phase-sensitive mode to normal x-rays and has potentially broad applications in biology and material sciences is described.
Abstract: Novel hard x-ray phase imaging microscopy that simply uses an objective and a transmission grating is described. The microscope generated an image that exhibited twin features of a sample with an opposite phase contrast having a separation of a specific distance. Furthermore, the twin features were processed to generate an image mapping the x-ray phase shift through a simple algorithm. The presence of the grating did not degrade the spatial resolution of the microscope. The sensitivity of our microscope to light elements was about 2 orders of magnitude higher than that of the absorption contrast microscope that was attained by simply removing the grating. Our method is attractive for easily appending a quantitative phase-sensitive mode to normal x-ray microscopies, and it has potentially broad applications in biology and material sciences.
79 citations
TL;DR: In this paper, the cross section of an InAs nanowire with a diameter of 150 nm epitaxially grown on a 111-oriented InP substrate was characterized using a combination of x-ray scanning microdiffraction and coherent diffraction imaging.
Abstract: The cross section of an InAs nanowire with a diameter of 150 nm epitaxially grown on a 111-oriented InP substrate was characterized using a combination of x-ray scanning microdiffraction and coherent diffraction imaging. Using an x-ray beam focused by a Fresnel zone plate, we were able to scan in real space and hence localize single nanowires on the substrate in the as-grown epitaxial state. For one single nanowire, the three-dimensional coherent intensity distribution in reciprocal space was mapped around the (111) InAs reflection. Using phase retrieval algorithms, the cross section of the wire was reconstructed with a spatial resolution of 8 nm along one direction.
60 citations
TL;DR: By comparing multilayered zone plates to a conventional monolayering zone plate, the effects associated with the number of building blocks and different dielectric materials in the building block on the efficiency of the transmission are presented.
Abstract: We numerically investigate the optical field enhancement by a metal/dielectric multilayered zone plate. The optical field enhancement at the focal point of a zone plate originates not only from surface plasmon polaritons (SPPs)-assisted diffraction process along the propagation direction of incident light, but also from multiple scattering and coupling of surface plasmons (SPs) along the metal/dielectric multilayer films. By comparing multilayered zone plates to a conventional monolayered zone plate, we present the effects associated with the number of building blocks and different dielectric materials in the building block on the efficiency of the transmission.
46 citations
TL;DR: A band-limited cosine zone plate appropriate for use with the single-sideband technique is derived and reduces calculation time for a hologram to approximately 75%.
Abstract: The single-sideband technique eliminates a conjugate image and zeroth order diffraction light, producing only a reconstructed image of a hologram. A band-limited cosine zone plate appropriate for use with the single-sideband technique is derived. The width of the zone plate is half that of a conventional zone plate in one direction. The proper selection of a transmitted spatial frequency band leads to an interlaced band-limited zone plate that has complex amplitudes in odd or even rows. The use of such a zone plate reduces calculation time for a hologram to approximately 75%. Experimental verification of this is presented.
46 citations
TL;DR: This is the first report with experimental results that autofocusing in OSH is possible without any searching algorithm or tracking process and synthesizes a real-only spectrum hologram in which its phase term contains information about a distance parameter.
Abstract: We present autofocusing in optical scanning holography (OSH) with experimental results. We first record the complex hologram of an object using OSH and then create the Fresnel zone plate (FZP) that codes the object constant within the depth range of the object using Gaussian low-pass filtering. We subsequently synthesize a real-only spectrum hologram in which its phase term contains information about a distance parameter. Finally, we extract the distance parameter from the real-only spectrum hologram using fringe-adjusted filtering and the Wigner distribution. Using the extracted distance parameter, we reconstruct a three-dimensional image of the object from the complex hologram using digital convolution, which bypasses the conventional blind convolution to reconstruct a hologram. To the best of our knowledge, this is the first report with experimental results that autofocusing in OSH is possible without any searching algorithm or tracking process.
45 citations
01 Sep 2009
TL;DR: In this paper, a Zernike phase contrast x-ray microscope has been developed at the undulator beamline 20XU and 47XU of SPring-8, which consists of a pseudo-Kohler-illuminating system, a Fresnel zone plate objective with outermost zone width of 100 nm, a Zvernike phase plate (0.96-μm-thick tantalum, λ/4 or 3λ/4 phase-shifter at 8 keV) installed at the back-focal plane of the objective,
Abstract: Zernike phase contrast x-ray microscope has been developed at the undulator beamline 20XU and 47XU of SPring-8. The system consists of a pseudo-Kohler-illuminating system, a Fresnel zone plate objective with outermost zone width of 100 nm, a Zernike phase plate (0.96-μm-thick tantalum, λ/4 or 3λ/4 phase-shifter at 8 keV) installed at the back-focal plane of the objective, and a visible-light conversion type cooled CCD camera as an image detector. A sectored (polygon) condenser plate is employed as the condenser in order to secure a large and flat field of view. Details and experimental results of the system will be shown.
43 citations
TL;DR: In this article, an analytical model was developed to study the subwavelength focusing characteristics of a binary phase Fresnel zone plate (FZP) under the illumination of linear polarized light.
Abstract: An analytical model is developed to study the subwavelength focusing characteristics of a binary phase Fresnel zone plate (FZP). The model shows that high numerical-aperture phase FZP under the illumination of linear polarized light produces rotationally asymmetric focal spot with beamwidth varying from 0.36λ to 0.79λ, where λ is the wavelength. On the other hand, rotationally symmetric focal spot with minimum beamwidth of 0.39λ can be obtained from the illumination of radial polarized light.
42 citations
TL;DR: In this article, a compact all-fiber zone plate lens is ablated on the surface of a mode-expanded hybrid fiber end by using a high precision femtosecond laser processing technique.
Abstract: We present a compact all-fiber zone plate lens directly ablated on the surface of a mode-expanded hybrid fiber end by using a high precision femtosecond laser processing technique. To achieve a sufficiently large beam size and focusing efficiency, a segment of a coreless silica fiber having a 200-mum diameter was adapted. Focusing properties of the zone plate lens were experimentally investigated and compared with numerical simulations.
01 Sep 2009
TL;DR: The BESSY x-ray microscopy group as discussed by the authors developed a new full-field X-ray micro-scope which employs an advanced xray optical concept and demonstrated that glass capillaries are well suited as condensers in the soft xray energy domain.
Abstract: The BESSY x-ray microscopy group has developed a new full-field x-ray micro- scope which employs an advanced x-ray optical concept. Traditionally, zone plate based condensers are used in x-ray microscopes providing an energy resolution of only E/�E � 500. In addition, this conventional monochromator concept requires a pinhole close to the sample restricting the available space for tomography applications. In our new BESSY microscope, a standard monochromator beam line provides a high energy resolution of up to 10,000 which permits NEXAFS studies. An elliptically shaped mono-capillary is used to form the hollow cone illumination necessary for sample illumination and to match the aperture of the objective. Calculations regarding the performance and accuracies needed are presented and characteri- zations of capillaries especially made for the BESSY soft x-ray microscope are shown. For the first time, we demonstrate that glass capillaries are well suited as condensers in the soft x-ray energy domain. Their focusing efficiency was measured to be 80% which is about an order of magnitude higher than the diffraction efficiency of zone plate based condensers.
01 Sep 2009
TL;DR: In this article, a laboratory scale EUV microscope is presented to be used, e.g., in future inspection of EUV masks and mask blanks in extreme ultraviolet lithography, where the system can be operated in bright and dark field mode.
Abstract: A laboratory scale EUV microscope is presented to be used, e.g., in future inspection of EUV masks and mask blanks in extreme ultraviolet lithography. The system can be operated in bright and dark field mode. For defect inspection purpose the dark field mode is preferred, with increased contrast and sensitivity of the system to small structures. The characteristics of the used Schwarzschild objective as imaging component such as large object field and moderate magnification become advantageous for high process speeds, whereas the detector pixel size (13 μm) does not give the spatial resolution in principle possible with the imaging optics. The presence of a defect causes a spot (with otherwise dark background) to appear on the detector. As necessary it can be zoomed in with the help of a second magnification step. For this purpose we suggest to employ a zone plate adapted to the system. The method's feasibility is demonstrated by means of experiments on test structures and the apparatus is characterized with regard to design parameters for commercial systems.
TL;DR: A laboratory x-ray microscope based on a compound zone plate that utilizes multiple diffraction orders to achieve high resolution while maintaining reasonable efficiency is presented.
Abstract: Improving the resolution in x-ray microscopes is of high priority to enable future applications in nanoscience. However, high-resolution zone-plate optics often have low efficiency, which makes implementation in laboratory microscopes difficult. We present a laboratory x-ray microscope based on a compound zone plate. The compound zone plate utilizes multiple diffraction orders to achieve high resolution while maintaining reasonable efficiency. We analyze the illumination conditions necessary for this type of optics in order to suppress stray light and demonstrate microscopic imaging resolving 25 nm features.
TL;DR: In this article, a double patterning zone plate fabrication process is developed to bypass the limitations of conventional single exposure fabrication to pattern density, such as finite beam size, scattering in resist, and modest intrinsic resist contrast.
Abstract: Soft x-ray zone plate microscopy is a powerful nanoanalytic technique used for a wide variety of scientific and technological studies. Pushing its spatial resolution to 10nm and below is highly desired and feasible due to the short wavelength of soft x rays. Instruments using Fresnel zone plate lenses achieve a spatial resolution approximately equal to the smallest, outermost zone width. In this work, a double patterning zone plate fabrication process is developed. based on a high resolution resist, hydrogen silsesquioxane (HSQ), to bypass the limitations of conventional single exposure fabrication to pattern density, such as finite beam size, scattering in resist, and modest intrinsic resist contrast. To fabricate HSQ structures with zone widths on the order of 10nm on gold plating base, a surface conditioning process with (3-mercaptopropyl) trimethoxysilane, 3-MPT, is used, which forms a homogeneous hydroxylation surface on gold surface and provides good anchoring for the desired HSQ structures. Using t...
TL;DR: In this article, a Fresnel zone plate is designed to perform the function of a doubly-hyperbolic lens, and the focusing characteristics of the zone plate and the lens are compared using both measured data and body-of-revolution finite-difference time-domain simulations.
Abstract: A Fresnel zone plate is designed to perform the function of a doubly-hyperbolic lens. The focusing characteristics of the zone plate and the lens are compared using both measured data and body-of-revolution finite-difference time-domain simulations. The results from this comparison are used to evaluate the use of zone plates as focusing elements in a free-space, focused-beam measurement system. A set of two zone plates is used to perform measurements of the material properties of a dielectric sheet, and the results are compared to the results from a standard system which uses two doubly-hyperbolic lenses.
01 Aug 2009
TL;DR: In this article, three different methods of generating digital Fresnel holograms of 3-D real-existing objects illuminated by incoherent light are reviewed, including a unique scanning system in which Fresnel zone plates (FZP) are created by a homodyne rather than the common heterodyne interferometer.
Abstract: We review three different methods of generating digital Fresnel holograms of 3-D real-existing objects illuminated by incoherent light. In the first method, a scanning hologram is generated by a unique scanning system in which Fresnel zone plates (FZP) are created by a homodyne rather than the common heterodyne interferometer. During the scanning, the FZP projected on the observed object is frozen rather than varied as previously. In each scanning period, the system produces an on-axis Fresnel hologram. The twin image problem is solved by a linear combination of at least three holograms taken with three FZPs with different phase values. The second hologram reviewed here is the digital incoherent modified Fresnel hologram. To calculate this hologram, multiple-viewpoint projections of the 3-D scene are acquired, and a Fresnel hologram of the 3-D scene is directly computed from these projections. This method enables to obtain digital holograms by using a simple digital camera, which operates under regular light conditions. The last digital hologram reviewed here is the Fresnel incoherent correlation hologram. In this motionless holographic technique, light is reflected from the 3-D scene, propagates through a diffractive optical element (DOE), and is recorded by a digital camera. Three holograms are recorded sequentially, each for a different phase factor of the DOE. The three holograms are superposed in the computer, such that the result is a complex-valued Fresnel hologram that does not contain a twin image.
01 Sep 2009
TL;DR: In this article, the authors describe a full-field transmission x-ray microscope (TXM) for automated cryo-tomography and nano-spectroscopy which is installed at the BESSY undulator U41.
Abstract: We describe the new full-field transmission x-ray microscope (TXM) for automated cryo-tomography and nano-spectroscopy which is installed at the BESSY undulator U41. For the first time in soft x-ray microscopy, an elliptically shaped single-bounce glass capillary is employed as condenser which collects the divergent radiation emerging from the exit slit of a focusing spherical grating monochromator (FSGM). The new TXM overcomes several limitations of conventional TXM setups, it provides an energy resolution up to E/ΔE = 104 which is well suited for spectromicroscopy. Furthermore, no pinhole is required close to the sample plane which facilitates flat sample holder geometry for nano-tomography. With its high energy resolution, the TXM also supports imaging in high orders of diffraction of the zone plate objective. Using this approach, a spatial resolution of 14 nm lines and spaces is demonstrated. In addition, we present selected applications from materials and life sciences.
TL;DR: By scanning an optically trapped fluorescent sphere, the vignetted collection region of the zone-plate imaging system is measured and the fluorescence collection efficiency is sharply peaked and has a lateral width of 550 nm, which agrees with numerical simulations.
Abstract: We demonstrate a form of scanning microscopy using a short-focal-length Fresnel zone plate and a low-NA relay telescope. Owing to a focal length of only 5 microm, the zone plate produces large wavefront tilt and consequently severe vignetting for off-axis illumination. By scanning an optically trapped fluorescent sphere, we measure the vignetted collection region of the zone-plate imaging system. The fluorescence collection efficiency is sharply peaked and has a lateral width of 550 nm, which agrees with numerical simulations.
TL;DR: Yan et al. as discussed by the authors proposed a modeling approach for x-ray dynamical diffraction from multilayer Laue lenses (MLLs) with rough interfaces, which is formulated from the perspective of the physical scattering process, very different from the conventional DWBA formalism.
Abstract: A modeling approach for x-ray dynamical diffraction from multilayer Laue lenses (MLLs) with rough interfaces is developed. Although still based on the principle of the distorted-wave Born approximation (DWBA), this model is formulated from the perspective of the physical scattering process, very different from the conventional DWBA formalism. Using this model, one can study x-ray scattering from rough interfaces in the regime of Fresnel diffraction and in the case of absorptive samples, for example, x-ray dynamical diffraction from MLLs with rough interfaces, which is hard to handle in the framework of the conventional DWBA. Theoretical simulations for various MLLs with rough interfaces are conducted. It is found that interfacial roughness results in a decrease in the local diffraction intensity, where the attenuation factor is a function of the root-mean-square (rms) roughness versus the local zone width ratio. This study shows that if all zones possess an identical rms roughness value that is less than half of the outmost MLL zone width, the focal broadening effect due to roughness is almost unnoticeable, provided that the mean position of the interface does not deviate from the required zone plate law. A further study shows that uncorrelated interfacial roughness can be treated themore » same as interfacial diffusion, in which case a roughness factor similar to the ''Debye-Waller factor'' can be used, and the pseudo-Fourier coefficients of the susceptibility function for an MLL [H. F. Yan et al., Phys. Rev. B 76, 115438 (2007)] have to be multiplied by this factor.« less
TL;DR: The construction of fractal generalized zone plates from a set of periodic diffractive optical elements with circular symmetry allows us, for instance, to increase the number of foci of a conventional fractal zone plate while keeping the self-similarity property within the axial irradiance.
Abstract: The construction of fractal generalized zone plates from a set of periodic diffractive optical elements with circular symmetry is proposed. This allows us, for instance, to increase the number of foci of a conventional fractal zone plate while keeping the self-similarity property within the axial irradiance. The focusing properties of these fractal diffractive optical elements for points not only along but also in the close vicinity of the optical axis are investigated. In both cases analytical expressions for the irradiance are derived. Numerical simulations of the energetic efficiency of fractal generalized zone plates under plane wave illumination are carried out. In addition, some effects on the axial irradiance caused by variations in the area of their transparent rings are shown.
TL;DR: It was found that, in the focal plane of silver zone plates, there were more evanescent waves and the propagating waves occurred at higher spatial frequencies relative to glass zone plates.
Abstract: The field properties of Fresnel zone plates with wavelength-scale focal distances were numerically investigated using the finite-difference time-domain method. The fields in the focal planes are analyzed using the angular spectrum representation, and the components of the propagating and evanescent waves are reconstructed. It was found that, in the focal plane of silver zone plates, there were more evanescent waves and the propagating waves occurred at higher spatial frequencies relative to glass zone plates. The propagating and evanescent wave components vary with the material and the number of zones in the zone plate structures. Our findings suggest that more evanescent waves and higher spatial frequency components of propagating waves can shape the field and obtain a smaller focus.
TL;DR: In this paper, a phase zone photon sieve (PZPS) is presented, which can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate.
Abstract: A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.
TL;DR: In this article, Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes.
Abstract: We show that Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes. The focusing process compresses the condensate by orders of magnitude despite inter-atomic repulsion. Crucially, the focusing dynamics are insensitive to quantum fluctuations of the atom cloud and largely preserve the condensates' coherence, suggesting applications in passive atom-optical elements, for example zone plate lenses that focus atomic matter waves and light at the same point to strengthen their interaction. We explore transmission zone-plate focusing of alkali atoms as a route to erasable and scalable lithography of quantum electronic components in two-dimensional electron gases embedded in semiconductor nanostructures. To do this, we calculate the density profile of a two-dimensional electron gas immediately below a patch of alkali atoms deposited on the surface of the nanostructure by zone-plate focusing. Our results reveal that surface-induced polarization of only a few thousand adsorbed atoms can locally deplete the electron gas. We show that, as a result, the focused deposition of alkali atoms by existing zone plates can create quantum electronic components on the 50 nm scale, comparable to that attainable by ion beam implantation but with minimal damage to either the nanostructure or electron gas.
TL;DR: In this work the concept of a Fresnel zone antenna for dual-band detection in the IR and millimeter wave region is presented, based on a Fresnels zone plate lens in theIR that is transformed to serve as a millimeter-wave antenna.
Abstract: In this work the concept of a Fresnel zone antenna for dual-band detection in the IR and millimeter wave region is presented. The design is based on a Fresnel zone plate lens in the IR that is transformed to serve as a millimeter-wave antenna. Two different designs are presented, a circular-zone design that gives a high diffractive efficiency in the IR and a square-zone design that gives a higher response in the millimeter band but a lower focusing efficiency in the IR. Both designs have an operation bandwidth with the same low frequency limit of 400 GHz (750 μm), which can be tailored by changing the number of Fresnel zones, and a high frequency limit of 4.5 THz (65 μm) for the circular-zone design and 5 THz (59 μm) for the square-zone design.
30 Nov 2009
TL;DR: In this paper, the fringe patterns produced by the zone plates in the presence of a quasi-parallel source were analyzed and compared with those obtained by Monte-Carlo simulations.
Abstract: Combination of Fresnel Zone Plates (FZP) can make an excellent telescope for imaging in X-rays. We present here the results of our experiments with several pairs of tungsten made Fresnel Zone plates in presence of an X-ray source kept at a distance of about 45 ft. The quasi-parallel beam allowed us to study sources placed on the axis as well as off the axis of the telescope. We present theoretical study of the fringe patterns produced by the zone plates in presence of a quasi-parallel source. We compare the patterns obtained from experiments with those obtained by our Monte-Carlo simulations. The images are also reconstructed by deconvolution from both the patterns. We compare the performance of such a telescope with other X-ray imaging devices used in space-astronomy.
TL;DR: A Fresnel liquid crystal (LC) lens with high diffraction efficiency and a low driving voltage is proposed, which may support progress in the electrical modulation of the optical properties of various optical systems.
Abstract: This investigation proposes a Fresnel liquid crystal (LC) lens with high diffraction efficiency and a low driving voltage. A Fresnel zone electrode was fabricated on a glass plate. A Fresnel zone-distributed electric field in the LC cell was induced by a proper driving voltage, yielding a concentric structure of LCs as a Fresnel phase lens. A remarkable diffraction efficiency of ~39%, close to the theoretical limit of 40.5%, was detected when the LC lens was probed using a polarized incident beam with a wavelength of 632.8 nm. The diffraction efficiency of the Fresnel LC lens was demonstrated to depend sensitively on the applied voltage. The most suitable driving voltage of the Fresnel LC lens was as low as 0.9 V. This study may support progress in the electrical modulation of the optical properties of various optical systems.
01 Sep 2009
TL;DR: In this paper, two layers of zone plates are stacked on top of each other to reach aspect ratios ≥ 20:1 for high efficient optics for soft and hard x-ray microscopy.
Abstract: Fresnel zone plates are the key optical elements for soft and hard x-ray microscopy. For short exposure times and minimum radiation load of the specimen the diffraction efficiency of the zone plate objectives has to be maximized. As the efficiency strongly depends on the height of the diffracting zone structures the achievable aspect ratio of the nanostructures determines these limits. To reach aspect ratios ≥ 20:1 for high efficient optics we propose to superimpose zone plates on top of each other. With this multiplication approach the final aspect ratio is only limited by the number of stacked zone plate layers. For the stack process several nanostructuring process steps have to be developed and/or improved. Our results show for the first time two layers of zone plates stacked on top of each other.
TL;DR: A soft x-ray microscope based on a phase-reversal zone plate was constructed and tested using high harmonic radiation as a coherent light source and showed that the measured resolution of the microscope was better than 100 nm.
Abstract: A soft x-ray microscope based on a phase-reversal zone plate was constructed and tested using high harmonic radiation as a coherent light source. The 61st harmonic centered at 13.3 nm was optimized in spectral sharpness and intensity by controlling the incident laser energy and chirp. A phase-reversal zone plate made of polymethyl methacrylate more than doubled the first-order efficiency. The nano patterns, imaged on an x-ray CCD with a magnification of 650, showed that the measured resolution of the microscope was better than 100 nm.