At CHESS, 2500 W total are absorbed by the first crystal of the double bounce monochromators located at the A2 and F2 wiggler beamlines. In order to dissipate this absorbed power and deliver the highest X-ray flux to an end station, we have explored the technique of internally cooling the silicon first crystals with water channels. This technique brings with it the need for reliable mechanical joints between the silicon diffracting surface and a glass or silicon water manifold. The joint must have structural strength to resist the internal water pressure and the cyclic heat load, be vacuum leak tight for operation in UHV, and not act as a source of residual strain in the crystal lattice of the diffracting surface. We have explored four bonding techniques which have been tested for their suitability to monochromator fabrication: direct silicon to silicon bonding, anodic glass to silicon bonding, a variety of ceramic and die attach adhesives (alumina, zirconia, silica/silver) and metallic diffusion bonding/brazing. In this paper, we characterize each method with respect to the requirements of structural integrity (bond tensile strength), residual strain (minimal effect on diffraction quality) and vacuum compatibility.

This paper will present work done at the NSLS to tailor the electron beam properties so as to maximize the performance of the photon beamlines. The electron beam properties of most importance to photon users are the total stored current, emittance, lifetime, and transverse stability. Recent and planned improvements in each of these properties will be discussed as well as the ultimate limits for each. The discussion of transverse stability will include high frequency motion, which can reduce the effective brightness, as well as slow drift during a fill and fill-to-fill reproducibility.

It is important to be able to accurately predict the spectral and angular distribution of undulator radiation properties when designing beamlines at new synchrotron radiation facilities or when performing radiation experiments at already existing beamlines. In practice, the particle beam emittance and beam energy spread must be taken into account in modeling these properties. The undulators fabricated today are made with small RMS phase errors, making them perform almost as ideal devices. Calculation tools for numerical modeling of undulator radiation sources (ideal and nonideal) will be discussed, and the excellent agreement with experimentally obtained absolute spectral flux measurements of undulator A at the Advanced Photon Source verifies the high accuracy of the computer codes and the high quality of the undulators being built today. Our focus here is on flux properties useful in practical beamline designs, and the chosen examples demonstrate the versatility of computer programs available to beamline designers and experimentalists.

Coherent properties of the X-ray beams provided by third generation synchrotron radiation sources are considered. A simple holographic technique to characterize the coherence is proposed. Requirements to the instrumentation such as X- ray optics, filters and windows are discussed. The possibilities of the coherent imaging techniques such as phase contrast, holography and interferometry with coherent high energy X-ray beams are demonstrated.

Capillary concentrators condense x-rays by multiple reflections down a gradually tapering capillary. They can provide sub-micron beam spots, and are promising candidates for use in the next generation x-ray microprobe beamlines. The weak energy dependence of their properties make them especially useful for energy scanning applications such as micro-XAFS. This paper examines the potential performance of capillary optics for an x-ray microprobe, as well as some practical issues such as fabrication and alignment. Best performance at third generation sources requires long capillaries, and we have been using fiber optics techniques to fabricate capillaries up to one meter in length. The performance of shorter (less than about 0.5 m) capillaries has often been found to agree well with the theoretical calculations, indicating the inner surface is a high quality x-ray reflector. These capillaries have been tested at the NSLS for imaging and micro-XAFS down to 2.6 micrometers resolution with excellent results. On an unfocused bend magnet line flux density approaching 10⁶ ph/sec/micrometers ² has been achieved. While nearly optimum profiles have been achieved for longer capillaries, the results have been disappointing, and alignment problems are suspected. The dramatic improvement in performance possible at third generation synchrotrons such as the APS is discussed along with improvements possible by using the capillaries in conjunction with coupling optics.

SPring-8 is a 3rd generation synchrotron radiation source that is characterized by high brilliance in the hard X-rays. Here we report our present status on the development of the focusing devices for hard X-rays. Supermirrors on silicon wafers were bent for 1D focusing to realize an energy- tunable hard X-ray focusing element with fixed focal length. A smooth high-reflectivity profile as a function of energy was realized with a wide energy band up to 40 keV. For imaging experiments such as for beam monitoring, linear and circular Bragg Fresnel zone plates were developed. An experiment to image the bending magnet source at the Photon Factory is described.

We present the x-ray performance on an ESRF synchrotron beamline of a focusing device based on the dynamical bending of a flat silicon plate coated with a 2.5 m d-spacing W/Si multilayer. The mirror was shaped by trial and error to a cylindrical ellipse using an optical profilometer. In a first experiment the device was bent to a 71-m radius to account for the demagnification factor and the energy of operation. With a monochromatic incident beam set at 9 keV a vertical spot size of 4.5 micrometers was obtained at 41 m from the source and 1 m from the multilayer, which agreed closely with theoretical expectations. Such good agreement was due to small residual slope error with respect to the ellipse: around 2 (mu) rad over a 150-mm length for radii greater than 50 m. Moreover, as the divergence of the incident beam was larger than the rocking curve width, less than 25% of the mirror could contribute, reducing the distortion to an even lower figure. With the same geometrical parameters the device exposed to the white beam (monochromator removed) lead to a vertical spot size of about 7 micrometers . Here the whole mirror surface cold reflect, which caused more distortion to the incoming beam but also gave rise to a much higher intensity. The gain in flux obtained with a gradient of d-spacing along the mirror surface is discussed. Finally, results with a Kirpatrick-Baez arrangement let expect in the near future a flux gain greater than 10⁴ with a 10 micrometers by 10 micrometers focal spot.

The x-ray diffraction properties of highly oriented pyrolytic graphite (HOPG) were studied for x-ray energies ranging from 4 to 60 keV. In particular, the secondary extinction thickness was determined by recording the peak and integrated reflectivity as a function of depth below the surface. The results showed that for the high quality material investigated a thickness of 200 to 300 micrometers was sufficient to get 80% of the maximum reflectivity that is obtained for a very thick plate. Primary extinction was important for low energy and still persisted at higher energies. Inhomogeneities of the mosaic structure were observed, too, that make this material not a truly ideal mosaic monochromator crystal. However, quite high peak reflectivities between 35% and 58% were measured at FWHM of 0.25 to 0.45 degrees. A 200 micrometers thick plate was then prepared and glued on a bending device to manufacture a monochromator or analyzer with variable curvature that works from flat down to a minimum bending radius of 10 cm. The successful tests of this device confirmed that HOPG plates much thinner than those commonly used as x-ray monochromators and analyzers still have high efficiency and can be curved to achieve dynamical focusing.

High-brightness synchrotron radiation sources provide highly polarized x-rays for a broad range of studies in materials science, biology, chemistry, and physics. Special insertion devices and x-ray optics such as phase plates can further enhance the purity and the tunability of the polarization of a synchrotron x-ray beam. There are therefore growing interests and activities in making better polarized x-ray sources, and analyzing complete polarization states (Stokes polarimetry) of an x-ray beam. In this paper we review the present status of x-ray optics development in this field. We will focus on the principles and the practicalities of the various methods for producing and analyzing polarized x- rays, especially circularly polarized x-rays.

At the Advanced Light Source an undulator beamline, with an energy range from 6 to 30 eV, has been constructed for chemical dynamics experiments. The higher harmonics of the undulator are suppressed by a novel, windowless gas filter. In one branchline high flux, 2% bandwidth radiation is directed toward an end station for photodissociation and crossed molecular beam experiments. A photon flux of 10¹⁶ photon/sec has been measured at this end station. In a second branchline a 6.65 m off-plane Eagle monochromator delivers narrow bandwidth radiation to an end station for photoionization studies. At this second end station a peak flux of 3 X 10¹¹ was observed for 25,000 resolving power. This monochromator has achieved a resolving power of 70,000 using a 4800 grooves/mm grating, one of the highest resolving powers obtained by a VUV monochromator.

The X-1A soft x-ray undulator at the NSLS is the source for our experimental programs in spectromicroscopy. We require both spatial and temporal coherence. Due to the relatively large horizontal divergence of the electron beam in the low (beta) straight section of the x-ray storage ring, it has been possible to split the beam using a scraping mirror into two branches: X-1A used by our program and X-1B used for high resolution spectroscopy. We are now rebuilding the X-1A beamline to provide improved resolving power and essentially linear trade-off between photon rate at the zone plate and resolving power for the soft x-ray spectromicroscopy experiments. This new beamline will exploit both additional floorspace due to the NSLS building expansion and increases in the brightness of the x-ray ring. Our beam will be further split into two separate beamlines, both of which will use toroidal mirrors to focus the source on the monochromator entrance slits horizontally and to focus on the monochromator exit slits vertically. This separation comes at no loss of coherent flux and permits low thermal loading on the optics, since we need little more than the coherent fraction of the beam at the Fresnel zone plate for microfocusing. Because of the small angular acceptance for spatially coherent illumination of the zone plates and the use of an approximately satisfied Rowland condition, our monochromators have sufficient resolving power with fixed exit arms. Experiments can then be placed near the exit slits, with spatial coherence established by the exit slit size. Resolving power will be controlled by adjusting the entrance slit alone with no change of spatial coherence. The zone plates will be overfilled to be less sensitive to beam vibration and drift.

We present first experimental data on a novel type of optical element for synchrotron radiation applications in the x-ray region: namely laterally-graded aperiodic crystals on the basis of Si_1-xGe_x alloys. The lattice parameter of such a gradient crystal containing up to some atomic % Ge in a Si single crystal changes nearly linearly along the plate of diffraction. Thus the variation of the Bragg angle of divergent incident light on the crystal can be compensated for. This opens up the possibility to operate a crystal monochromator in nearly crystal limited resolution in the whole energy range above 2 keV at the full vertical divergence without a collimating premirror. Simultaneously the reflected spectral intensity can be increased considerably as compared with a conventional Si-crystal monochromator.

Though optimization softwares are commonly used in visible optical design, none seems to exist for soft x-ray optics. It is shown here that optimization techniques can be applied with some advantages to X-UV monochromator design. A merit function, suitable for minimizing the aberrations is proposed, and the general method of computation is described. Samples of the software inputs and outputs are presented, and compared to reference data. As an example of application to soft X-ray monochromator design, the optimization of the soft X-ray monochromator of the ESRF microscopy beamline is presented. Good agreement between the predicted resolution of a modified PGM monochromator and experimental measurements is reported.

The first synchrotron radiation beamline using a 4-m-long undulator at the 12 GeV storage ring PETRA delivers hard x- ray photons usable up to 300 keV. In order to reduce the low energy photon flux and the related thermal load on the beamline optics, graphite, beryllium, aluminum, copper, and iron filters or windows are installed. With a planned upgrade of the undulator, a deflection parameter of K equals 2.59 will be reached. The total radiated power of the undulator will then reach (with closed gap) about 15 kW. The central power density will be about 107 W/mrad². Therefore, the design of the filters and windows which interact directly with the white beam becomes a very challenging engineering problem. The heat transfer and thermal stress analyses of PETRA filters and windows are presented. Different filter or window thicknesses, sizes, at different deflection parameters of the undulator, are discussed. Improved filter or window designs are proposed.

A Laue-Laue-Laue x-ray interferometer with the inclined third crystal plate was fabricated to demonstrate wavefront- dividing interferometry in x-ray region. Observed interference patterns showed the effects of spatial coherence of the incident wave, in addition to the incident angle dependent spatial fringes expected from the dynamical theory of diffraction. From the visibility of the interference pattern, the source size used was estimated using Van Cittert-Zernike theorem.

A beamline for high resolution spectroscopy with elliptically polarized X-rays is described. The working energy range is large, from 20 eV to above 1800 eV. The resolving power is on the order of 10,000 at low energies (20 eV - 200 eV) and 6000 at high energies (200 eV - 1800 eV). This is achieved using a variable deviation angle plane grating monochromator. A single grating, with one line density and a varying groove depth, is used to cover the entire energy range. The beamline has been designed to operate with either one or two x-ray beams propagating simultaneously through the monochromator and to the experimental station. Switching between polarizations at rates of 0.1 Hz and slower is accomplished in the single beam mode by alternating the output of the elliptically polarized undulator source between left and right polarization. Fast polarization switching, at rates of 100 - 1000 Hz, is provided in the two beam mode by mechanical chopping between two photon beams, one of which is right circularly polarized, and the other left circularly polarized.

A step-and-scan type scanning scheme has been investigated for the purpose of simplifying the high-precision scanning mechanism adopted in the 6.65-m off-plane Eagle type monochromator on an undulator beamline of the Advanced Light Source at Lawrence Berkeley National Laboratory. In this scheme it is proposed to scan over a wavelength range of 80 - 180 nm by covering a range of 0.99 (lambda) _t - 1.01 (lambda) _t at a time by simply rotating the grating fixed at the position for a wavelength (lambda) _t to which the undulator is tuned. When the undulator is tuned to another (lambda) _t, the grating is translated to a new fixed position and scanning is made by simple grating rotation. A ruled grating with varied line spacing and straight grooves and a holographic grating recorded with spherical wave- fronts were designed to match the proposed scanning scheme and to meet the required energy resolution of approximately 1.0 cm^-1 over the entire scanning range. The results of ray tracing show that the designed gratings with 2400 grooves/mm and 6.1-m radius of curvature would provide a resolution of -1, a good correction of astigmatism, and a grating travel distance of only 11 or 14 mm over the scanning range of 80 - 180 nm.

In our recent x-ray photon correlation spectroscopy (speckle) experiments at NSLS, one of the challenges is to increase the coherent photon flux through a pinhole, whose size is chosen to match the beam's horizontal transverse coherence length l_h. We adopted an approach to vertically focus the x-ray beam so as to match its vertical transverse coherence length l_v (at NSLS X13, l_v approximately 50 l_h, l_h approximately 12 micrometers at 3 KeV) with l_h. By demagnifying the vertical size by a factor of l_v/l_h, we expect to increase the intensity of the x-rays through the pin hole by the same factor while keeping the beam coherent. A piece of commercial 3/8' thick float glass, by virtue of its low surface roughness (approximately 3 angstroms rms), good reflectivity in the low photon energy range of interest and low cost, was chosen as the mirror material. A computer controlled motorized bender with a four point bending mechanism was designed and built to bend the float glass to a continuously variable radius of curvature from -700 m (intrinsic curvature of the glass surface) to < 300 m, measured with the Long Trace Profiler at the BNL Metrology Lab. This mirror bender assembly allows us to continuously change the focal length of the x-ray mirror down to 0.5 m under our experimental conditions. At the NSLS X13 Prototype Small Gap Undulator beamline, we were able to focus the x-ray beam from a vertical size of 0.5 mm to approximately 25 micrometers at the focal point 54 cm from the mirror center, thus increasing the photon flux density by a factor of 20. Results also show that, as expected, at an incident angle of 9 mrad, the mirror cuts off the harmonics of the undulator spectrum, leaving a clean 3 KeV fundamental for our experiments.

Beamline optical components and their dynamic holding and bending systems are qualified at the ESRF in the optical metrology laboratory, which has been moved recently into the ESRF experimental hall. Software and hardware enhancements of the five instruments used to perform these ex situ characterizations are described. In situ beamline mirror metrology using a wavefront analyzer has been introduced in ID24 and ID20 beamlines. The design of the analyzer, its architecture with respect to the mirror chambers and its use in active optics control with mechanical and bimorph benders are described in this paper.

Chemically vapor deposited silicon carbide (CVD-SiC) is the most important material of mirrors for high-brightness synchrotron radiation beamlines, though the material is too difficult to be machined. It takes quite a long time to polish SiC substrate to make mirrors. This paper intends to reduce the machining time to make CVD-SiC mirrors by using ultra-precision grinding technology. The CVD-SiC sample has been ground into 0.4 nm rms in surface roughness by a resinoid-bonded diamond wheel and an ultra-precision surface grinder having a glass-ceramic spindle of extremely-low thermal expansion. The surface roughness of ground samples were measured with TOPO-3D and AFM. 88.7% reflectivity has been obtained on the ground CVD-SiC flat surface, measured with X-ray of 0.834 nm in wavelength at the grazing incidence angle of 0.7 - 0.95 degree. The reflectivity depends upon the angle between the direction of incident beam and grinding marks on the sample. The relationship between the surface roughness and grinding conditions was also discussed.

The optical design of a varied line-space spectrograph for the multi-channel recording of NEXAFS spectra in a single `snapshot' is proposed. The spectrograph is to be used with a bending magnet source on beamline 7.3.2 at the Advanced Light Source. Approximately 20 volts of spectra are simultaneously imaged across a small square of material sample at each respective K absorption edge of carbon, nitrogen, and oxygen. Photoelectrons emitted from the material sample will be collected by an electron imaging microscope, the view field of which determines the sampling size. The sample also forms the exit slit of the optical system. This dispersive method of NEXAFS data acquisition is three to four orders of magnitude faster than the conventional method of taking data point-to-point using scanning of the grating. The proposed design is presented along with the design method and supporting SHADOW raytrace analysis.

The very low emittance of new synchrotron sources and the increasing number of micro-focusing applications make the production of highly stable and well defined beams increasingly necessary. The use of flexible mirrors whose curvature can be changed while maintaining a correct figure appeared to be a very attractive solution. For over two years, the ESRF has been developing a new approach which consists of making an X-ray mirror from an active material such as piezoelectric ceramics. With respect to conventional bender this concept, already used in astronomical and laser applications, has the advantages to be mechanics free, very compact and relatively cost effective. This paper presents the status of the ESRF's developments in this field. First, theoretical and technical descriptions of the system are given. Experimental tests of various configurations confirmed the potential of this concept. For example, two 150 mm long bimorph mirrors set into a Kirkpatrick-Baez geometry gave a focused spot of 10 micrometers (vertical) X 20 micrometers (horizontal). Finally, the developments of in-situ control systems (strain gauges, optical devices), necessary to fully exploit the capabilities of these active optics, are discussed.

Although x-ray micro-foci can be produced by a variety of diffractive methods, grazing incidence mirrors are the only route to an achromatic focus. In this paper we describe our efforts to produce elliptically shaped mirrors with the very high figure accuracy necessary for producing a micro-focus. The motivation for this work is provided by the need to produce achromatic foci for a range of applications ranging from tunable micro-focus x-ray photoelectron spectroscopy ((mu) -XPS) at soft x-ray energies to micro-focus white beam x-ray diffraction ((mu) -XRD) at hard x-ray energies. We describe the methodology of beam bending, a practical example of a system we have produced for (mu) -XRD, and results demonstrating the production of a surface with micro-radian figure accuracy.

X-ray mirrors for synchrotron radiation beamlines must have low roughness and small figure errors to preserve source brilliance. Gravitationally-induced slope errors can be particularly detrimental for large vertically-deflecting mirrors on ultra-high brilliance third-generation beamlines. Although mirror support can greatly reduce gravitational distortions, in some cases mirror support can complicate dynamic bending. We discuss techniques for controlling gravitational distortions with particular emphasis on removing gravitational distortions from simple bendable mirrors. We also show that in beamlines with parallel mirrors, gravitation induced slope errors can be cancelled through the mirror pair; gravitation induced slope errors of the first mirror can be cancelled by matching slope errors with opposite signs on the second mirror.

A new design of a bent crystal analyzer for high energy resolution inelastic X-ray scattering has been recently proposed. It has been theoretically predicted that an analyzer with reflecting planes at a certain angle with respect to a crystal surface, bent with two different radii of curvature, will have the same energy resolution as a perfect crystal. The first experimental measurement obtained at the Advanced Photon Source of a bandwidth of such an analyzer is presented. The overall energy resolution of the analyzer and monochromator observed with a narrow beam is equal to 16.4 meV (FWHM) at 13.84 KeV.

The first in-situ distortion profile measurement of a high heat load mirror by use of the penta-prism LTP is presented. A maximum height distortion of 0.47 micron in tangential direction over a length of 180 mm was measured for an internally water-cooled mirror of a undulator beam line at ELETTRA while exposed to a total emitted power of 600 W (undulator gap 30 mm and current 180 mA). The experiment has an accuracy and repeatability of 0.04 micron. The test schematic and the test equipment are presented. Two measuring methods to scan a penta-prism being installed either outside or inside the vacuum chamber are introduced. Advantages and some possible applications of adopting the penta-prism LTP to make the in-situ profile test are explained.

A portable electro-optical system capable of real-time measurements of surface distortions down to 0.5 (mu) rad is described, limited primarily by the short-term system stability. Methods to reduce the system fluctuations and to enhance the detectable resolution are explained. Although designed for use with mirrors for synchrotron radiation sources, this system has the flexibility to be applied to other optical components. The prototype system has been tested on a sample mirror piece, and preliminary results are presented. A brief discussion about the extension of this metrology unit to adaptive optics is also given.

Since many years CILAS developed active mirrors for synchrotron radiation beamlines. The paper presents the recent developments of bimorph structures usable for x ray mirrors, monochromator crystals, and gratings. The adaptation of the structure to the 3 applications above mentioned is done by choosing the upperplate material and surface coating. The bimorph structure is designed to produce a simple spherical bending of the active plate, or more sophisticated shapes as ellipsoids or parabola. The bimorph structure can be delivered in a mechanical housing able to properly support it. High voltage amplifiers with digital input fitted to control the shape as well as a curvature measurements system may be delivered providing the possibility of closed loop operation. Standard versions of bimorph mirrors and gratings are available. Most of the development works was done under ESRF support.

Ruled diffraction gratings and even holographic ones have a `surface texture' or an `inherent roughness' that is part of the grating making process. Using the new scanning probe microscopy (SPM), we can now see the structure that has been long suspected but not revealed using scanning electron microscopy. Also using the SPM, we can review the surface structure in the film prior to ruling as well as after. Gaining this experience, we have been able to make adjustments to the diamond tool and weight to improve the final products.

A nearly stigmatic Plane Grating Monochromator (PGM) under commissioning for the new undulator beamline at the Synchrotron Radiation Center will provide a resolving power > 10000 as it scans from 8 to 240 eV. Scanning requires the precise, simultaneous rotation of a plane mirror and a combined rotation-translation of a plane grating in close proximity to one another inside a UHV chamber. The required scanning motions are significant due to the large energy range covered by a single grating. The mirror and grating rotate nearly 23 and 33 degrees respectively and the grating translates approximately 200 mm. Sub-arcsec angular resolution allows several steps to be taken across the monochromator's energy resolution. Both rotations utilize a combination stepping motor-piezoelectric actuator scan drive that is controlled with a feedback loop using a laser interferometer to measure the in-situ rotation of the optics. The grating mechanism is supported via bellows to an external stepping motor driven stage that travels directly on an inspection grade granite block. The stage position is controlled with a feedback loop using a precision linear encoder. A positional accuracy and vertical stability of a few micrometers is achieved on the grating translation which prevents the image from shifting at the exit slit and introducing energy calibration errors.

The X-ray undulator BW1 at the storage ring DORIS is a high brightness source for the spectral range from 2 to 20 keV. The undulator beam is used by three experiments with different distances to the source. The new optical elements allow the adaptation of the focal lengths to the needs of the experimental set-ups. The optical concept consists of a premirror with different optical surfaces, a double crystal monochromator and a focusing second mirror. Sagittal focusing is achieved either by using the cylindrical part of the premirror or by a bend crystal for a monochromatic beam, meridional focusing is done with a pneumatic driven mirror bender for the second mirror.

Reflective optics operated at grazing angle of incidence has a good polarization transfer function and was preferred to focus or steer the X-ray beam on the ESRF beamline ID12A which is dedicated to X-ray dichroism. The present paper reports on the design of a double mirror device (VF-2M) that is located downstream with respect to the monochromator and can refocus the X-ray beam vertically very near the sample location. This system combines two identical mirrors (L equals 600 mm; W equals 40 mm; T equals 12 mm) made of bulk CVD-SiC which were polished to a very precise cylindrical shape: when no bending forces are applied, each mirror has a concave curvature radius of 1 km with a slope error