Reflection Zone Plates Research Articles

High resolution x-ray absorption spectroscopy using a laser plasma radiation source

In this article we present a setup of a spectrometer for near edge x-ray absorption spectroscopy at the carbon K-edge (284 eV). The spectrometer works with a laser produced plasma as x-ray source and a single x-ray optical element in grazing incidence configuration called off-axis reflection zone plate. Using different sample foils we were able to demonstrate a spectral resolution of E/ΔE≈600. The positions of specific absorption peaks are in agreement with data measured at synchrotron sources. Since the off-axis zone plate is a focusing system, the x-ray flux in the detector plane is high enough to record an absorption spectrum on a charge-coupled device detector with a single shot. In the single shot modus a spectrum can be recorded before a sample degradation takes place. This will enable time-resolved experiments using pump-probe techniques.

Nanometer focusing of X-rays with modified reflection zone plates

Transmission Fresnel zone plates and x-ray waveguides are presently the best high-resolution optical elements used in x-ray microscopy and micro-probing. The spatial resolution of zone plates is defined not only by the technological limit of about 10 nm but also by the effects of volume diffraction, even for high-order zone plates. The physical nature of a waveguide limits the theoretical spatial resolution to 10 nm, corresponding to the minimum thickness of film able to fulfil the conditions necessary for optical mode formation. Here, we show that reflection zone plates and Bragg–Fresnel lenses can overcame the resolution limit of transmission zone plates and waveguides and make it possible to achieve spatial resolution into the sub-nanometer range, subject to source size limitations. Such optics can be used with existing third-generation synchrotron radiation sources, as well as with x-ray laser sources, e.g., free-electron lasers.

A reflective half-cylindrical Fresnel zone plate antenna with low backward radiation for wireless LAN

A reflective half-cylindrical Fresnel zone plate antenna with low backward radiation for wireless LAN

X-ray brilliance measurements of a subpicosecond laser plasma using an elliptical off-axis reflection zone plate

An absolutely calibrated spectrograph based on a new single x-ray optical element, namely, an elliptical off-axis reflection zone plate, has been used for brilliance measurements of a laser-produced plasma of solid carbon and boron nitride. The spectral range investigated, λ≈2.1–4.3 nm, covers the emission from excited H- and He-like carbon states to the ground state. The plasma was generated by a subpicosecond high-intensity KrF*-laser pulse at an intensity of 2×1016 W/cm2. Under these conditions more than 1011 photons/sr per pulse were emitted in the strongest lines, demonstrating that this plasma can serve as an intense x-ray source. The measured spectra were in good agreement with a simulation that used the radiation program ration for an electron density of ne=4×1022 cm3 and an electron temperature of Te=90 eV. Measurements of spectral changes at different angles of incidence of the laser beam confirmed theoretical predictions for line intensities.

Off-axis reflection zone plate for quantitative soft x-ray source characterization

A compact system for high-resolution spectroscopy and quantitative photon flux and brilliance measurements of pulsed soft x-ray sources is described. The calibrated system combines a novel elliptical off-axis reflection zone plate with charge-coupled device detection for simultaneous spectral and spatial measurements. Experiments on a water-window droplet-target laser-plasma source demonstrate λ/Δλ⩾1000 spectral resolution and absolute flux and brilliance measurements. © 1997 American Institute of Physics.

On-die diffractive alignment structures for packaging of microlens arrays with 2-D optoelectronic device arrays

A novel technique for aligning a microlens array to an electrically packaged optoelectronic device array is presented: reflective Fresnel zone plates (FZP's) are fabricated on the device die to provide registration spots during alignment. A proof-of-concept experiment in which an MSM array was aligned to a microlens array with an accuracy of better than 9 microns is described.

Fabrication of high-resolution multilayer reflection zone plate microlense for the soft x-ray range

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.

Fabrication of diffraction X-ray elements

The use of focusing elements in the X-ray range shows promise for nondestructive chemical analysis of samples with spatial resolution up to fractions of a μm. This paper considers the problems of fabricating Fresnel zone plates of different types: amplitude- and phase-transparent zone plates and reflective zone plates formed on a multilayer mirror, as well as microstructures with a specified zone profile.

Zone-plate Interferometers

Abstract Interferometry gives a precise indication of the relative separation of two coherent sources. If the sources are images produced by an optical system, their positions are controlled by the respective components of the system. Interferometry can therefore be used to measure the relative positions, in three-dimensions, of the optical components. This paper describes a common-path interferometer which uses zone plates as beam-splitting and imaging components. A two-dimensional array of reflective zone plates is used to define a three-dimensional array of positions, i.e. an optical ‘space frame’. Particular examples of wavefront geometry are used to show how the sensitivity to displacement can be varied by controlling the relative shear of the wavefronts. The device has applications in metrology, for example in checking the positioning performance of multi-axis measuring machines.

Angle eikonals of plane and spherical zone plates

The angle eikonals are determined for plane and spherical zone plates of transmission and reflection types. From them, the Seidel coefficients are obtained. These are compared with those of a thin lens as its index of refraction becomes infinity and with Murty’s aplanatic reflective zone plate.

New approaches in analysis of soft X-rays using gratings

The properties of the state-of-the art transmission gratings are discussed and put in context with reflection gratings, zone plates and multi-layer mirrors. Efficiency as well as resolution of the systems are comparable but the different approaches have widely different emphasis and fields of application. The importance of alignment and continuous monitoring of the performance of a grazing incidence monochromator is emphasized and results from an analysis of alignment effects are presented. New developments in multiple combinations of different optical elements are discussed and proposed as important applications of synchrotron radiation.