Within less than 10 years of operation, third generation synchrotron light sources have proven to be mature, with exceeding their target specifications by far and providing brilliances in the 10²⁰ photons/s//0.1%BW/mm²/mrad². In the future, the main parameters that can still be improved are the horizontal emittance and the beam current. Even if the trend in brilliance increase achieved during the last 30 years is over, a brilliance increase by 2 orders of magnitude can still be envisaged for an X-ray storage ring light source. This paper will review the ESRF approach to a future machine: choice of design parameters, evaluation of optics, critical issues.. A few examples will illustrate the foreseen applications of higher brilliance and increased transverse coherence.

The optics metrology laboratory of Sincrotrone Trieste is operating some non-contact interferometers since 1992, in order to characterise slope errors, figure deviations and surface roughness for synchrotron radiation optics (SR) up to 1.4 metres in length, prior to their installation at the beamlines. During these years, prompted by the increasing needs of experimentalists, the requirements for FEL and SR optical components have become more and more severe. We will review here the history of our measurements during the last nine years, comparing the match between the given specifications and measured optical quality of the delivered items. We will also illustrate which has been the evolution of the main optical concepts, that has ultimately boosted the suppliers to develop machining and testing methods to a novel level of accuracy.

Plasma CVM (chemical vaporization machining) and EEM (elastic emission machining) systems were developed for coherent X-ray optics fabrication. Figure-correction performances were tested in the spatial wavelength range from submillimeter to several hundreds mm, and those processes were certified to be promising technique to fabricate next-generation mirrors for coherent X-ray beams. A wave-optics simulation code was also developed to feed scientific analysis back to the fabrication technology. A figure measurement technique was also proposed to satisfy the suggestions from the wave-optics simulations. Simulated results indicated the necessity of the figure measurement with subnanometer accuracy having lateral resolution more than submillimeter.

The properties of optical components are described that are required by synchrotron x-ray scattering techniques needing to fully exploit the coherence properties of third- generation sources. For example, phase imaging and microfocusing applications require reflecting surfaces with errors much smaller than a nanometer up to spatial frequencies in the mm^-1 range while keeping roughness on the sub-Angstrom level. The two major challenges being addressed in this paper are the accuracy of the metrology and the technology of the machining based on the metrology for deterministic corrections. The low emittance and the stability of the synchrotron source combined with x-ray position sensitive detectors are suitable to measure the reference wavefront with picometer accuracy. The deformation of this wavefront by a reflecting mirror leads to surface error maps whose accuracy corresponds to the conditions for coherence preservation. These maps are used as input for an ion-beam milling machine correcting these height errors on grazing incidence mirrors. First results are presented and limits of these techniques including possibilities of multilayer corrections are discussed.

X-ray mirrors are polished and often coated optical substrates used on many synchrotron x-ray beamlines to reflect, focus, steer, or filter x-ray beams. Because their performance depends strongly on their surface quality, they are usually evaluated after delivery, independently (from the vendor), for compliance before acceptance by the buyer. This paper summarizes results of surface roughness and slope error measurements of mirrors delivered to the Advance Photon Source (APS) and evaluated in the metrology laboratory during the period 1996 - 2001, using non-contact surface profilometry. For all the mirrors evaluated, the measured root-mean square (rms) slope error values range from 0.5 to 4.7 (mu) rad rms, and the surface rms values range from 0.9 to 4.3 A rms. Most of the measured mirrors have met the user specifications.

We discuss the possibility of using Stitching Interferometry for the surface shape metrology of X-ray Mirros. Indeed, Stitching Interferometry combines a large field of measurement with a high lateral resolution. In other words, it provides large-scale and medium-scale measurements in a single instrument. Small-scale deformations is considered here to be roughness, and will not be dealt with in this article. The only potential problem in Stitching Interferometry is large-scale fluctuation. This is not due to the Stitching Process itself, but to small measurement errors which get amplified by the long dimension of the typical X-ray Mirror. This will be addressed, and it will be shown that it need not be a problem. As we have not completed our series of experimental measurements, we will illustrate our article with stitching measurements performed in large MegaJoule components (800 x 400 mm), and show an example of Mixed Stitching, involving measurement files of different origin.

Walter Type-I optics, which reflect X-rays twice with their confocal paraboloidal and hyperboloidal reflectors, have commonly been used in X-ray astronomy. These two reflectors usually consist of two thin substrates with conical shapes in order to obtain a large effective area above 2 keV. However, such telescopes tend to have poorer imaging quality due to approximation to conical shapes and misalignment of the two substrates. In order to reduce the degeneration in the imaging quality, we formed two reflectors from one thin substrate. The accuracy of the angle between two reflectors is determined by the tolerance of the mandrel used to form the thin foil substrate. At RIKEN we make the mandrel using a precision processing method. Here we present the results of our preliminary experiment on substrate forming.

This paper reports on the performances of a test prototype mirror, based on the Piezoelectroic Bimorph Mirror technology, which has been designed and manufactured (in collaboration with the French optical company SESO) for the national Japanese 8 GeV storage ring Spring-8. The device consists of two 150 mm long modules assembled side-by-side. It exhibits superior surface quality with respect to previously manufactured long piezoelectric bimorph mirrors, as the junctions between modules do not introduce any distortion on the reflecting surface. The mirror can effectively compensate low frequency components of the figure error/waviness left by polishing. Two different simple optimisation methods have been validated: ex-situ in the metrology lab (Adaptive Optics correction and control algorithm) and, for the first time, in-situ at the beamline (Hartmann test). After optimisation with coherent x-rays at the 1 km long SPring-8 beamline, elliptical shaping was achieved with sub (mu) rad level precision for the slope error rms. The associated height error is as small as 8 nm rms. over 200 mm illuminated length. An extremely sharp gaussian 8 micrometers FWHM wide spot size was obtained by vertically demagnifying the undulator source. It has also been demonstrated that it is possible to bend the mirror to an arbitrary, user-defined, shape; i.e. sinusoidal.

The sagittal focusing of x-ray beam diffracted on symmetrically cut crystals with a longitudinal parabolic groove on their diffraction surfaces has been proved experimentally and the results have been already published. This kind of focusing is based on the refraction phenomena occurring during Bragg x-ray diffraction. In this paper our new developments in this field are reported. First, it was shown experimentally that in some cases a channel-cut crystal monochromator with longitudinal parabolic grooves can be replaced by a single crystal with a round hole drilled parallel to diffracting planes. This substantially simplifies the manufacturing of such a focusing monochromator. Second, it has been experimentally proved that the refraction effect, on which the focusing is based, may be substantially enhanced by cutting the longitudinal parabolic groove into the surface of an asymmetrically cut crystal (or drilling a hole whose axis is tilted with respect to the diffracting planes). A very simple formula describing the focusing properties for this case is derived. Finally, the results of the first experiment on the meridional focusing of x-ray beam diffracted on a crystal with a transversal groove on its surface are reported. Some experimental results are compared with the results of ray- tracing simulations, which were developed for this purpose.

A novel experimental method is presented for evaluating the crystal lattice imperfections using a reflection X-ray microscope (RXM). An X-ray microscope using an X-ray refractive lens is constructed on the reflected beam axis of the crystal. This method has a unique advantage that the image contrast due to the integral reflectivity variation and due to the phase-contrast of the crystal surface are easily discriminated by de-focusing technique. The sample crystals chosen were silicon circular Bragg Fresnel zone places (BFZPs). The BFZPs had circular zones on Si(111) plane with two different groove depths of 3.9 micrometers and 5.9 micrometers . The validity of the de-focusing method was proved and a clear difference of the X-ray microscope images was observed for the BFZPs with different groove depth.

We have conducted a systematic characterization of (111)- and (100)- oriented synthetic diamond crystals comparing the best presently available specimens of two types (Ib and IIa). The samples were grown by the two major diamond producers, namely the De Beers Industrial Diamonds (Pty) Ltd. in South Africa and the Sumitomo Electric Industries Ltd. in Japan. Double-crystal x-ray diffractometry with microscopic spatial resolution and x-ray topography were employed. The type IIa crystals showed much less pronounced defect structure than the Ib crystals for the (100)- orientation, but the (111) samples were comparable. A clear correlation between the distribution of nitrogen impurities in the Ib crystals and the defect structure was observed. The rocking curve widths from small regions of all specimens were very close to theoretical values on the arcsec level, whereas for larger sample areas they were broadened due to both local defects and crystal curvature. The quality of the IIa crystals from De Beers and Sumitomo was comparable.

The evolution of intrinsic stress in multilayers and its behavior with growing number of periods and/or during radiation exposure, i.e. thermal treatment, becomes important in many X-ray optical applications. In Ni/C X-ray optical multilayers fabricated by pulsed laser deposition (PLD) at room temperature with typical period thickness d approx. 4.0 nm microstructure and intrinsic stress are analyzed with growing period number up to the layer stack delamination. Microstructure of single layers and interfaces and morphology of the total layer stack were investigated by means of transmission electron microscopy (TEM), X-ray reflectometry and diffraction. A clear indication of nano-crystallites was found for the Ni-layers, whereas the carbon layers were always amorphous. The diffraction pattern of a 300 period Ni/C layer stack hint at a hexagonal structure of the Ni crystallites with the (011)-lattice plane parallel to the Si substrate surface. Thus the elastic misfit between the Ni- and C-layers seems to be minimized. To investigate the evolution of stresses in the growing up Ni/C multilayers depth dependent stresses in the Si (100) substrate were analyzed using X-ray results of the stress tensor for Si-crystal of the substrate averaged over different penetration depths (0.6 and 3.6 μm). The found dependence of the substrate stresses on the total layer thickness point at low compressive stresses in the PLD-fabricated Ni/C X-ray optics in the range below -100 MPa at least up to a total layer thickness of 1200 nm (300 periods). An increase of the compressive stresses was obtained only for stacks of more than 300 periods. A delamination of the layer stack in part was observed at 900 periods.

To fill the gap in energy resolution dE/E between a few percent for multilayer x-ray optics and a few 10^-4 for perfect crystal optics we have developed narrow bandpass multilayers consisting of Al₂O₃ and B₄C layers. Their resolving power was precisely determined on the ESRF bending magnet beamline BM5 using a white beam and a Si(111) analyzer crystal. Scans in the (n,+m) and in the (n,-m) scattering geometry return consistent results. With a sample of 680 double layers we have obtained a spectral resolution of 0.27% at energies around 12 keV which is in good agreement with earlier studies using monochromatic x-rays.

We have fabricated La/B4C multilayer films by magnetron sputtering for the use as x-ray mirrors at energies below 190 eV, particularly for the detection of boron Ka x-rays at 183 eV, and compared them to Mo/B4C multilayers that are currently used in x-ray fluorescence spectrometers for this purpose. Transmission electron microscopy and synchrotron soft x-ray reflectometry at energies between 50 and 525 eV were used to study the structural quality and the x-ray optical performance of the multilayers. The results show a significant improvement of the reflectance at 183 eV with simultaneously improved suppression of other, undesired x-ray energies, indicating that La/B₄C has a high potential to replace Mo/B₄C in many x-ray optical applications below 190 eV. As an example, a comparison between La/B₄C and Mo/B₄C multilayers was performed by laboratory x-ray fluorescence measurements of the boron Ka emission using samples of B4C and borophosphosilicate glass. The improvements of the peak intensity and the lower limit of detection amounted to about 64% and 29%, respectively. The thermal stability of La/B₄C multilayers was also investigated.

We present the results of a study of the influence of the deposition process parameters on the X-ray reflectivity of multilayer mirrors for applications at energies above 10 keV. The coating process used is DC magnetron sputtering and we have begun an optimization analysis for two material combinations: W/Si and Pt/C. The following process parameters were considered: argon pressure, distance between cathodes and substrate, and sputtering cathode currents. The samples are coated on 2' polished silicon wafers and their X-ray reflectivity is measured by performing a specular scan with an 8.05 keV (Cu K-alpha) X-ray beam. The reflectivity scans were analyzed with the IMD software and the fitted interface roughness values were correlated with the deposition parameters. The analysis of variance (ANOVA) statistical treatment of the data allows the determination of the contribution of each process parameter to the reflectivity and establishes which of the parameters need tighter control.

We studied about new design of supermirror and inerfacial roughness for the X-ray telescope above 40 keV. We have developed hard X-ray telescope above 10 keV using platinum-carbon multilayer supermirror. In our balloon borne experiment, named InFOC(mu) S launched in this June, the supermirror expand the upper-limit of energy band of X-ray telescope up to 40 keV. We are trying to improve supermirror design to have energy band up to 70 keV. In previous design, the absorption of upper layers and lower-limit of layer thickness prevent us to extend the energy band. In this paper, we optimize design parameters of supermirror and use second Bragg peak, and we obtained high reflectivity up to 70 keV. We studied about interfacial roughness of platinum-carbon multilayer to design the supermirror, because the interfacial roughness is very serious problem such high energy region. In many cases, simple Debye-Waller factor can't represent measured reflectivity. We introduced two different roughness for Pt/C and C/Pt interfaces. This model well fit the data and make us possible to design the supermirrors.

Many software programs are available in the market for the design of optical instruments. However, most of them are not suitable for modeling x-ray optical elements. The simulation of the x-ray source characteristics (emission, geometry) strongly depends on the type of generator used (synchrotron insertion devices, FEL, x-ray tube, laser-generated plasma, etc.). The optical elements are usually grazing mirrors, multilayers and crystals, with very different characteristics than optical elements used in other photon ranges. In addition, the reflectivities of such optical devices must be calculated taking into account tabulated optical constants. In the last years we have developed a new approach for creating a common tool for x-ray optics and sources modeling, lumping together small programs from different origins and authors, adding an unified x-ray database and gluing all this in a user-friendly and powerful data manipulation environment. The result is the XOP code which is now used in many synchrotron facilities. In addition to the first level calculations available in XOP, we have incorporated an interface to the popular x-ray tracing code SHADOW that allows the simulation of the complete beamline and produces accurate values of beam sizes, divergences, flux and energy resolution. I will review the present state of XOP and the SHADOW Visual Interface. I will then present the plans for a new version in preparation. Then I will discuss new ideas and possible requirements for simulating the forthcoming x-ray optics for fourth generation x-ray sources.

Total reflection grazing incidence mirrors are the only devices available to focus X-ray beams resulting in an achromatic focus. The elastic bending of polished, specially shaped beams to obtain the shapes of parabolic and elliptical reflectors is described in this paper. X-ray focusing devices based on this principle have been used at EMBL Hamburg Outstation in some variety or other ever since the latter half of the 1970's. We review the methodology of beam bending, calculation of beam shape and present a versatile program for the comparison of various designs.

Simultaneous measurements of the integrated reflectivity of a mica crystal for different orders of reflection have been performed at a predefined Bragg angle of 45 degree(s) with use of a new method. The method is less time consuming than previous techniques and provides data with small statistical errors. It can be readily used for the calibration of x-ray crystal spectrometers. The paper presents experimental results for Bragg reflections up to the 22^nd order. The obtained experimental results are compared with theoretical predictions.

We present recent test results and discuss design challenges on x-ray optical compo-nents for the wiggler sources at CHESS and for the proposed energy recovery linac (ERL) source at Cornell. For the existing wiggler sources, a new white-beam collimating mirror has been installed and tested at F-line and some preliminary test results are pre-sented. For the proposed ERL, three types of x-ray optical components are identified and considered: (1) high-heat-load capable optics for high-power and high-power-density in-sertion-device sources, (2) brilliance preserving optics that can provide high transverse coherence, and (3) optics used to manipulate, preserve and produce short x-ray pulses.

Microelectronics technology involving photolithography and highly anisotropic plasma etching techniques was applied to fabricate planar parabolic refractive lenses. A set of Si planar parabolic lenses with apertures from 0.5 to 1.8 mm and 200 microns deep has been fabricated especially for high energy X-rays (E > 50 keV). Focusing properties in terms of the spot size and the efficiency in the energy range from 50 to 100 keV have been studied at the ESRF ID15 beamline. Linear focusing by single lens and by two-lens system as well as two-dimensional focusing by two lenses in cross geometry has been realized. Features of refractive collimator based on a set of planar lenses have been investigated and a technique for evaluation of the beam divergence in a micro radian range has been proposed. Future applications of proposed planar lenses are discussed.

Spatially extended quasi-monoenergetic x-ray beams will allow improved performance for many applications in diagnostic radiology. X-rays with well-defined energies between 15 keV and 20 keV can be used to enhance the contrast of mammography images while reducing dose to the patient. Diagnostic radiology using iodine, xenon, or barium as a contrast agent can be made more sensitive by using nearly monoenergetic x-rays with energies just above and below their K edges near 33 keV, 34 keV, and 37 keV. We describe the design and preliminary performance measurements of a prototype thin film multilayer x-ray narrow-band filter or monochromator designed to produce fan-shaped beams of x-rays at 33 keV. A set of closely spaced thin foil substrates coated with graded Pt/C multilayers provides energy selectivity when illuminated by a diverging broad-band x-ray beam incident on the foils at near-grazing angles from 0.2 degrees to 0.3 degrees. The individual thin foil mirrors are mounted into top and bottom precision alignment structures formed by deep reactive ion etching 1-mm thick silicon wafers.