The paper describes a concept to improve the present photon-induced scanning Auger- microscope, a high-flux micro-spectroscope which allows electron spectroscopy with high spatial resolution, in-situ chemical mapping, and microstructuring of organic and organometallic compounds. It utilizes high-brightness, quasi-monochromatic undulator radiation from BESSY storage ring. The present electron energy resolution (>= 0.5 eV) appears sufficient but the spatial resolution (>= 3 micrometers ) can be significantly improved. The new concept compromises grazing incidence optics in a two stage reduction scheme in order to combine an increase of photon flux with an increase of the spatial resolution to 0.2 micrometers . The key component of the improved instrument is an ellipsoidal grazing incidence mirror for which optimization calculations have been performed. These include diffraction, surface roughness and slope errors as well as manufactural limitations taking technical realizability into account.

A demonstration x-ray optic has been produced by diamond turning and replication techniques that could revolutionize the fabrication of advanced mirror assemblies. The prototype optic was developed as part of the Advanced X-Ray Astrophysics Facility, Spectrographic project. The initial part of the project was aimed at developing and testing the replication technique so that it could potentially be used for the production of the entire mirror array comprised of up to 50 individual mirror shells.

Using doubly bent crystal optics, x-ray imaging of a plasma source with doubly bent crystal optics is investigated, employing both the ray-tracing and the wave-optics approaches. The description of the x-ray plasma imaging experiment is given, which includes the considerations of the crystal, the reflection, and the bending radius selections for achieving a spectral resolution up to 10^-4 without compromising the diffracted intensity. The principles of these two approaches are discussed and applied to the experimental case for the x-ray radiation of the Ly(beta) line of hydrogen-like Argon ions. Results of the calculations are compared and for the discrepancies explained. It is found between these two approaches that the principal difference in the results of the calculations can be attributed to the optical Fresnel diffraction effect, which is not taken into account in the ray-tracing method.

Characterization of bent crystals used in x-ray spectroscopic instrumentation is carried out, which includes different methods for measuring the reflection curves of bent crystals and integrated reflectivities. The integrated reflectivities of a cylindrically bent PET crystal within the wavelength range of 0.3 - 0.8 nm are presented. The measured data are compared with calculations using both kinematic and dynamic theories. Based upon the x-ray dynamic theory of bent crystals, the optimal selection of the x-ray wavelength, crystal reflections and bending radius, which are necessary to observe the fine details of the reflection curve, are determined. To obtain both the energy band and the angular width of the probing beam in the order of 10^-5 radian, a double-crystal spectrometer in a dispersive configuration, which consists of quartz (20.3) symmetric and silicon (111) asymmetric reflections, is suggested. As a result, the former has a nearly normal incident case, which makes possible a (Delta) (lambda) /(lambda) value of approximate 2 X 10^-5; the latter reflection contributes mainly to the reduction of the angular width of the diffracted beam. A rotating device with high angular precision to measure the reflection curve is discussed.

Cylindrical (hyperbolic-parabolic Wolter I) mirrors have been electroformed from nickel over an electroless nickel-phosphorous (NiP) plated aluminum mandrel in support of the NASA AXAF-S x-ray spectrometer program. The electroless nickel was diamond turned and polished to achieve a surface finish of 10 angstroms rms or better. Gold was then plated on the nickel alloy after an electrochemical passivation step. Next a heavy layer of pure nickel was plated one millimeter thick with computer controlled stress at zero using a commercial PID program to form the actual mirror. This shell was removed from the NiP alloy coated mandrel by cryogenic cooling and contraction of the aluminum to release the mirror. It is required that the gold not adhere well to the NiP but all other plated coatings must exhibit good adherence. Four mirrors were fabricated from two mandrels prepared by this method. Two mirrors were made from each mandrel. Electrolytically deposited gold was used on three parts and vacuum deposited gold (1500 angstroms) on the fourth. The mandrel surface finish was about 10 angstroms rms at the time of plating in each case. The area of each part is 0.7 square meters (7.5 square feet).

Beijing Electron Positron Collider set up by High Energy Physics Institute in 1988 is one of the greatest scientific engineering in China and Beijing Synchrotron Radiation Lab. was set up in 1989. One of its seven light beamlines set up in 1990, i.e. 4B9B is used for experiment of synchrotron radiation X-ray photoemission energy spectra. The front focus mirror of the light beamline 4B9B is a supersmooth toroidal mirror at a distance of 11900 mm from synchrotron radiation source. The light beamline is at grazing angle of 3 degree(s) with respect to the surface of the supersmooth toroidal mirror and received angles in both horizontal and vertical directions are 4.5 mrad and 1 mrad respectively. The light beam is focused by the toroidal mirror and meridian plane is imaged on entrance slit S₁ of spherical grating monochromator. Image distance of meridian plane is 6025 mm and image distance of sagittal plane is 13155 mm. The dimension of the mirror is 230 mm X 80 mm X 35 mm. The curvature radii of the meridian and sagittal planes are 152860 mm and 654 mm respectively. The paper describes optical system design, the technical characteristic, fabrication technique and improved machine tool and test methods on the supersmooth toroidal mirror. We have improved a machine tool to universal machine tool for machining aspherics. A series of aspherics have been tested by means of directly imaging. Results for testing profile of the mirrors and the radii by both meridian and sagittal planes indicate that blur circle of image is less than 0.1 mm in diameter, error of the radii is +/- 1 approximately 2% and surface roughness is 0.5 nm RMS. The technical specification meets requirements of users and has reached advanced level in the world on the same products abroad.

The imaging properties of a test model of the SODART telescopes have been studied using an expanded beam X-ray facility at the Daresbury synchrotron. The encircled power and the point spread function at three energies 6.627 keV, 8.837 keV and 11.046 keV have been measured using 1D and 2D position sensitive detectors. The data have been used to calculate the Half Power Diameter (HPD) for three different SODART focal plane detectors. The High Energy Proportional Counter (HEPC), the Low Energy Proportional Counter (LEPC) and the 19 element solid state array detector (SIXA). At 6.627 keV and 8.837 keV the HPD is 2.5 - 3.0 arcmin for all detectors whereas it is somewhat larger at 11.046 keV for HEPC and LEPC but essentially unchanged for SIXA. Finally, the data are used to point to improvements that can be introduced during the manufacture of the flight telescopes.

The High Throughput X-Ray Spectroscopy Mission (XMM) is a `Cornerstone' Project in the ESA long-term Program for Space Science. The satellite observatory uses three grazing incidence mirror modules coupled to reflection grating spectrometers and X-ray CCD cameras. In order to achieve a large effective area, each XMM mirror module consists of 58 Wolter I mirrors which are nested in a coaxial and cofocal configuration. This high packing density requires the production and integration of very thin mirror shells with diameters ranging from 300 to 700 nm. In this paper, we first present the optomechanical design of an XMM mirror module with an emphasis on thermal control and straylight analysis. We then describe the X-ray test results of a mirror development model with an electro-optical breadboard of a CCD focal plane camera.

The scientific instrumentation onboard the Italian X-ray Astronomy Satellite SAX foresees four X-ray Mirror Units operating in the energy range 0.1 - 10 KeV with spatial resolution of 1 arcmin Half Power Radius. The Mirror Units are composed of thirty nested confocal and coaxial very thin double cone mirrors made by a nickel electroforming replica technique. The paper presents the X-ray characterization data obtained at the PANTER facility on the Flight Mirror Units.

Physitron has constructed a grazing incidence nested optic designed to collect and collimate a broad energy bandwidth of diverging soft x-rays (nominally 1.5 keV) emanating from a point source. Although this optic was designed to collimate rather than focus x-rays, our optic is similar to the nested conical foil x-ray telescopes which have been constructed and successfully used by NASA. Key differences exist between our optic and NASA's telescopes. First, the aperture of our optic is 28 cm² which is considerably smaller than NASA's telescopes. Second, the reflectors in NASA's telescopes are contained in an annular ring, leaving the middle of the optic open. Our optic has a much smaller open area at its radial center. These differences required an innovative fabrication technique in which the reflective rings are formed as complete rings from lacquer-smoothed aluminum foil instead of forming the reflectors as quadrants as in NASA's technique. This paper will discuss the key design considerations and procedures for the collimator in addition to a description of the fabrication technique used.

The x-ray microcalorimeter represents a revolutionary development in x-ray astronomy, because it permits spectra to be obtained which rival Bragg crystal spectra in resolution, and exceed a proportional counter in efficiency. We describe a rocket borne x-ray spectrograph, consisting of a microcalorimeter detector array placed at the focus of a Wolter I collector. We demonstrate that a modest collecting area of 60 cm² is sufficient to determine the abundances of O, Ne and Fe in the interstellar medium.

We have been developing optical filters for ESA's X-ray astronomy project XMM (X-Ray Mirror Mission) where specific CCDs will serve as focal plane cameras on board the observatory. These detectors are sensitive from the X-ray to the near infrared spectral region.

Optical constant determination of thin films is critical to the design of x-ray multilayers. In the x-ray region, surface roughness, interfacial roughness, interdiffusion, volume anisotropics, etc. all act to reduce the reflection. A method is described to include all imperfections that make a real film different from an ideal film into the `optical behavior' values for each individual layer and the multilayer as a whole. These `optical behavior' values can then be used to accurately predict the performance of the multilayer.

We report the design of multilayer reflective filters for the self-filtering cameras of the NUVIEWS project. Wide angle self-filtering cameras were designed to image the CIV (154.9 nm) line emission, and H₂ Lyman band fluorescence (centered at 161 nm) over a 20 degree(s) X 30 degree(s) field of view. A key element of the filter design includes the development of (pi) -multilayers optimized to provide maximum reflectance at 154.9 nm and 161 nm for the respective cameras without significant spectral sensitivity to the large cone angle of the incident radiation. We applied self-filtering concepts to design NUVIEWS telescope filters that are composed of three reflective mirrors and one folding mirror. The filters with narrowband widths of 6 and 8 nm at 154.9 and 161 nm, respectively, have net throughputs of more than 50% with average blocking of out-of-band wavelengths better than 3 X 10^-4%.

Multilayers as coatings for grazing incidence telescopes have the potential of effectively improving the performance of telescopes coated with high-Z elements. For broad-band high energy (+10 keV) applications the multilayers, called supermirrors, are ideal. In this presentation we present the preliminary results of a feasibility study of a multifocus Kirkpatrick-Baez telescope. We conclude that high quality multilayers can be performed on relevant thin large flat substrate with adequate uniformity, and that existing deposition chambers can produce the multilayers at a rate of 0.42 m² per day, so that a coating reflectors for a 1200 cm² aperture telescope would take 8.5 months. The only remaining unanswered question is whether these thin supermirror-coated reflected can be configured to a 2 - 3' tolerance.

The 33.8 angstroms emission from laser-irradiated targets was studied using a concave mirror with a W/B₄C multilayer coating. The mirror had peak normal-incidence reflectance of 1.8% at a wavelength of 33.8 angstroms. Imaged were radiatively heated, low-density plastic and silica foams, x-ray laser targets, and a gas-filled enclosure.

In an era of rigid budget controls and limited resources, the efficiency of coating operations is of great concern. With expenditure reduction in mind, an investigation was initiated into the costly materials and procedures necessary in the production of X-ray optics. The expense of certain specialty substrates required us to evaluate the feasibility of a substrate recycling program. Substrate reuse could reduce initial cost and save acquisition time. Past research in this area centered mainly on stripping or resurfacing optics. Although this has been proven to be successful, it is time consuming and unsatisfactory for figured optics. One solution to this problem is to simply overcoat the optic with a new multilayer coating. If it could be demonstrated that there were no adverse effects to the performance of the optic, then the efficiency gains to both time and budget would be evident. Also worth of investigation, would be to explore the minimum thicknesses that are needed for proper masking of past multilayer coatings. In this paper we seek to examine these points and to determine which parameters of the x-ray overcoatings could adversely effect the performance. By exchanging coating elements, their thickness, and their composition we will demonstrate that there is not degradation of reflectivity. Included will be research substantiated by scanning electro microscope, and Mg-K(alpha) X-ray diffraction.

Various multilayers have been fabricated and analyzed in our laboratory over the past six years. We report effects of aging on the reflectivities of these multilayers. Several mechanisms can cause changes in multilayer performance: surface contamination, inter-layer diffusion, oxidation. We seek to study these mechanisms by modeling the measured performance with a multilayer computational code. A majority of our multilayers are Molybdenum-Silicon structures. We also have measurements on several Tungsten-Carbon multilayers, in which variations in effective 2d spacing are more readily determined because of their narrow passbands.

In response to the needs of a solar imaging program, we designed, fabricated, and evaluated several multilayer mirror coatings for an x-ray telescope to image the sun at 9.39 nm (Fe XVIII). The telescope optic is a single-mirror Herschelian design operating at near normal incidence. Simulations using commercially available software guided preliminary multilayer mirror design. Based upon these calculations, dual ion beam assisted deposition techniques generated trial films and multilayers. Structural evaluations were carried out on a multiaxis x- ray (0.154 nm) reflectometer with specular reflection and non-specular scattering measurements. Performance parameters for the multilayers at design wavelength were obtained from the NIST EUV reflectometer at the SURF II storage ring.

It is well known that in addition to roughness control, the most critical factor in the fabrication of x-ray multilayers is the accuracy of film thickness monitoring. Thickness accuracy and reproducibility of the x-ray multilayer deposition process can be improved by compensating for the film thickness variations in subsequent layers. We report the design of the `Bremsstrahlung Optical Monitoring System' (BOMS) for in situ multilayer spectral reflectance measurements and individual film optical thickness monitoring. The designed monitoring system, BOMS, utilizes the bremsstrahlung that occur during an electron beam deposition as the x-ray source and two energy sensitive detectors for the reference and sample beam reflectance measurements. In addition, the BOMS will create a powerful tool for in situ multilayer design, thus providing fabricated x-ray coatings with ultimate spectral performance.

For XUV-imaging of the Sun with sub-arc second resolution it is proposed to use the Herschel telescope with aspherical (toroidal) multilayer mirror working at out-of-axis angle 1.5 - 2 degree(s). In that case aberrations (mainly astigmatism) are sufficiently reduced so high resolution better than 1' may be obtained. In comparison with the Ritchey-Chretien two- mirror telescope which is regarded as perspective to reach closely the diffraction limited resolution, the Herschel telescope is more simple, less critical to adjustment and has higher throughput. Toroidal mirrors with diameter D equals 30 mm, focal length F equals 800 mm and ratio of sagittal and meridional radii of curvature R_m/R_s equals 1.001 have been made on super polished fused quartz substrates (roughness better than 7 A). After shape correction mirrors were covered by Mo-Si coating for 175 A wavelength band. The mirrors were used in high resolution channel of the TEREK-C telescope designed for the CORONAS space solar observatory which was launched on March 2, 1994. An example of the solar image obtained by this telescope is presented.

Creation of Bragg X-ray optics based on transmitted and reflection crystals, bent on cylindrical or spherical surfaces, is discussed. Application of such optics for obtaining one and two dimensional monochromatic images of different plasma sources in the wide spectral range 1 - 20 angstroms are described. Samples of spectra obtained with spectral resolution up to (lambda) /(Delta) (lambda) approximately 1000 and spatial resolution up to 18 micrometers are presented.

X-ray focusing using square channel capillary arrays is reviewed. We review our theoretical understanding of these devices and go on to examine their potential in the context of x-ray astronomy as an approach to the construction of a lobster-eye telescope. We show that a reasonably small device has the potential, in principle, to improve the sensitivity of wide field of view x-ray telescopes by an order of magnitude. We go on to briefly review our experimental work and indicate that these devices are getting close to realizing their theoretical potential.

Here we report on the fabrication and analysis of two different types of laterally structured multilayers, which act as highly efficient x-ray optical elements for focusing or spectral dispersion of soft x-rays at (near) normal incidence. The microfocusing of soft x-rays at (near) normal incidence with plane reflection optics can be obtained by multilayer Bragg-Fresnel zone plates. A circular condensor zone plate structure (2.9 mm diameter, 417 zones, inner zone radius 50 micrometers , outer zone width 0.9 micrometers ) has been recorded by holographic lithography followed by ion beam etching into a Mo-Si multilayer mirror of 24 periods and a doublelayer thickness of 7.2 nm. The focusing properties analyzed by soft x-ray reflectometry at (lambda) equals 13.8 nm show a focal spot size smaller than 40 micrometers measured 160 mm behind the multilayer zone plate. Multilayer blazed gratings offer the opportunity for highly resolved spectral dispersion of soft x-rays due to the possible combination of high efficiency and high diffraction orders with almost the whole intensity diffracted in one diffraction order. The sawtooth profile of a blazed grating structure (1221 l/mm, blaze angle 1.5 degree(s)) has been ruled into a 200 nm thick Au-film which has been deposited onto a plane glass substrate. A Mo/Si multilayer of 15 periods and a doublelayer thickness of 7.2 nm has been deposited onto the grating substrate. In order to smooth the rough Au-surface and to prevent interdiffusion of the Au-film with the upper Mo-Si multilayer a carbon film has been evaporated onto the Au-grating surface before the deposition of the soft x-ray coating. This procedure results in a significant increase of diffraction efficiency. The multilayer grating has been matched working on blaze in the third diffraction order, where an absolute diffraction efficiency of 3.4% at (lambda) equals 14 nm has been measured, while only 1.1% has been achieved for a similar grating without a carbon interlayer.

Silicon wafers have excellent optical properties--low microroughness and good medium-scale flatness--which make them suitable candidates for inexpensive flat-plate grazing-incidence x- ray mirrors. On short spatial scales (< 3 mm) the surface quality of silicon wafers rivals that expected of the Advanced X-Ray Astrophysics Facility high-resolution optics. On larger spatial scales, however, performance may be degraded by the departure from flatness of the wafer and by distortions induced by the mounting scheme. In order to investigate such effects, we designed and constructed a prototype silicon-wafer x-ray telescope. The device was then tested in both visible light and x rays. The telescope module consists of 94 150-mm-diameter wafers, densely packed into the first stage of a Kirkpatrick-Baez configuration. X-ray tests at three energies (4.5, 6.4, and 8.0 keV) showed an energy-independent line spread function with full width at half maximum of 150 arcseconds, dominated by deviations from large-scale flatness.

By stacking many very thin extraordinarily smooth sheets of material with a gap between each to form open channels, a new class of optical components for x-rays, ultraviolet light and neutrons can be made. Radiation propagates via grazing incidence reflections from the channel walls. If the stack is bent, radiation can be made to bend through large angles, and by properly forming the entrance or exit aperture, concentrators or collimators can be fabricated. This paper contains a discussion of the theory and fabrication of these laminar microchannel optics. Direct control over the reflecting surface and the stacking of the channels give these optics some unique advantages over other microchannel optics. Channel walls can be made as thin as 12 micrometers and coated with nearly any desired reflecting material and surface roughness below 2 angstroms can be readily achieved. Open spaces between the planar channels are as small as 8 micrometers or as large as desired. These optics provide the capability to bend, focus, or collimate broad energy bandwidths of radiation with optics that have apertures of up to several cm², high throughput, and small size.

We employed anisotropic etching of single crystal silicon wafers for the fabrication of micron- scale optical elements. We have succeeded in producing silicon lenses with a geometry suitable for 1-d focusing x-ray optics. These lenses have an aspect ratio (40:1) suitable for x- ray reflection and have very good optical surface alignment. We have developed a number of process refinements which improved the quality of the lens geometry and the repeatability of the etch process. A significant progress was made in obtaining good optical surface quality. The RMS roughness was decreased from 110 angstroms for our initial lenses to 30 angstroms in the final lenses. A further factor of three improvement in surface quality is required for the production of efficiency x-ray optics. We present new wafer geometries designed to test the effect of the etch process on surface roughness.

We present results of the experimental tests of various arrays of reflectors acting as X-ray optical elements. Planar reflectors were aligned with a common center of curvature to create a 1D focusing array. The experiments were carried out using X-ray radiation in the spectral range 3.5 keV to 7 keV produced at beamline X-27C of the National Synchrotron Light Source at the Brookhaven National Laboratory. The initial beam had width of 90 mm, a focal distribution had a width of 8 mm and a maximum intensity gain of 7.3, as measured with a 0.4 mm diameter pinhole. An X-ray beamsplitter consisting of arrays of reflectors has also been designed and tested. The separation of X-ray beams is 40 mrad and intensity of each of two beams is about 0.32 of the original X-ray beam.

The MOnitoring X-ray Experiment (MOXE) is an X-ray all-sky monitor to be launched on the Russian Spectrum-X-Gamma satellite. It will monitor several hundred X-ray sources on a daily basis, and will be the first instrument to monitor most of the X-ray sky most of the time. MOXE will alert users of more sensitive instruments on Russia's giant high energy astrophysics observatory and of other instruments to transient activity. MOXE consists of an array of 6 X-ray pinhole cameras, sensitive from 2 to 25 keV, which views 4(pi) steradians (except for a 20 degree(s) X 80 degree(s) patch which includes the Sun). The pinhole apertures of 0.625 X 2.556 cm² imply an angular resolution of 2 degree(s).4 X 9 degree(s).7 (FWHM on-axis). The flight instrument will mass approximately 118 kg and draw 38 Watts. For a non-focussing all-sky instrument that is limited by sky background, the limiting sensitivity is a function only of detector area. MOXE will, for a 24 hrs exposure, have a sensitivity of approximately 2 mCrab. MOXE distinguishes itself with respect to other all-sky monitors in its high duty cycle, thus having unprecedented sensitivity to transient phenomena with time scales between minutes and hours.

A first attempt to fabricate high reflectivity W/Be and Mo/Be multilayer mirror coatings for near normal incidence and grazing angle applications is reported. Forty layers each of W and Be were laid down alternatively on super polished fused silica substrates by sputter deposition with layer thicknesses of 16 angstroms and 40 angstroms, respectively and a 80 angstroms thick Be capping layer. Soft x-ray reflectivity measurements were carried out using the NRL reflectometer at the Brookhaven National Synchronous Light Source. Measurements at two grazing angles and photon energies yielded the following peak reflectivities: 14.3% (at 14.68 degree(s) and 439 eV) and 7.5% (at 20.2 degree(s) and 307 eV). Model peak calculations taking into account interlay roughness indicate layer roughness of 5.4 angstroms (rms) and a BeO thickness of 70 angstroms in the Be capping layer. In an attempt to reduce interlayer roughness and/or intermixing by reducing the bombardment of high energy Ar neutrals on the growing layers, experiments are underway to replace Ar as the sputter gas with Xe for the W/Be multilayer coatings.

We describe an experiment to quantify reflected X-ray Absorption Fine Structure (XAFS) in the mirrors to be used on the Joint European X-ray Telescope (JET-X). This instrument is due to be launched on the Russian Spectrum-X platform into deep orbit in December 1995. As part of the calibration program, samples of the Wolter type I, X-ray mirrors were taken to the Synchrotron Radiation Source at the Daresbury Laboratory and exposed to monochromatic X- rays across the energy range of the gold M_I - M_V edges (2 keV to 3.5 keV). We outline our research program and present preliminary results of both direct and reflected XAFS measurements at a variety of incident angles. We find that, while the position of the M_II edge occurs within 3 eV of its tabulated value, the M_I, M_III, M_IV and M_V edges are shifted to higher energies by approximately 10 eV, 13 eV, 40 eV and 40 eV, respectively. We attribute these discrepancies to inaccuracies in the field equations used to generate atomic and nuclear data tables.

Grazing-incidence optics are quite sensitive to molecular and particulate contamination. For NASA's Advanced X-ray Astrophysics Facility-Imaging (AXAF-I), the sensitivities of the flux scale to contamination on the mirrors' surfaces are typically 0.4% per angstrom of a hydrocarbon film and 0.4% per 10^-5 fractional areal coverage by particulates. In view of the goal of calibrating the flux-scale to a few-percent accuracy, it is clearly essential to adopt rigorous procedures to control and to monitor both molecular and particulate contamination. Traditional approaches to monitoring contamination for optical surfaces--using optical witness samples in conjunction with facility airborne monitors--are essential during ground operation. However, such techniques do not directly monitor changes in x-ray reflectance or even in contamination of the mirrors themselves; nor can they determine differences in contamination between ground calibration and orbital operations. In order to transfer the AXAF-I flux scale from ground to orbit, AXAF-I will incorporate x-ray- fluorescing radionuclide sources in the forward contamination cover. Comparison of the telescope's throughput, for these x rays, at ground calibration with that at the commencement of orbital operations will validate the flux-scale calibration. If ground-to-orbit changes were to occur, such a comparison would facilitate correction of the flux scale.

In previous papers, we reviewed the development of multilayer optics, the successful application of this new technology to astronomical observations, the evolution of astronomical multilayer optics instrumentation through several generations, and the matching of multilayer bandpasses to the coronal spectrum. These developments have resulted in the acquisition of sub-arc-second images of the sun in several wavelength bands, permitting solar structures to be simultaneously observed over temperatures prevailing in the chromosphere (approximately 10,000 K - 100,000 K), the transition region (approximately 100,000 K - 1,000,000 K) and the corona (> 1,000,000 K). In the present paper, we discuss the selection of spectral bandpasses that permit a set of isothermal coronal and chromospheric images of diagnostic quality to be formed.

The TAUVEX space astronomy experiment to image wide sky areas in the 140 - 280 nm spectral region is part of the SODART telescope complex on SRG, and functions as a separate scientific instrument and as a service system for the spacecraft. The experiment consists of three bore-sighted telescopes with 20 cm diameter Ritchey-Chretien optics. Each telescope is equipped with a four-position filter wheel and can select one of six UV bands in the spectral region of operation. The photon-counting, imaging detectors cover a field of view of 0 degree(s).9, with 80% of the energy from a point source within about 10 arcsec. The image is sampled at 3 arcsec intervals. The sensitivity is such that stars of 10 - 11 mag in the UV are detected in 2 sec, and in a typical SRG pointing of 5 hours stars as faint as 20 mag are detectable. TAUVEX provides off-line aspect solutions for the SODART focal plane instruments and on-line fine pointing information to the SRG attitude and control system. The experiment is constructed by El-Op, Electro-Optical Industries Ltd., and is financially supported by the Government of Israel, through the Israel Space Agency and the Ministry of Science and Arts. By mid-1994 four models of TAUVEX had been produced and supplied to the SRG integrators: size and mass models in 1992, a thermal model in early 1993 and an engineering model in spring 1994. A qualification model is being tested intensively at El-Op these days and the flight model will be ready, after testing, burn-in and calibration, by the end of 1994. TAUVEX is a light-weight, low-power, versatile UV imaging experiment with significant redundancy, which is not limited to operations on-board SRG. The system may operate on other platforms, including small satellites, if such an opportunity occurs.

We present two first generation holographic recording solutions suitable for use in converging beam, grazing incidence applications. The aberration control of both solutions is excellent, providing detector limited spatial and spectral resolution over most of the usable bandpass. The solutions provide either a astigmatism minimized or spectral resolution optimized solutions. These gratings can be produced at a substantially reduced cost compared to their mechanically ruled counterparts and with significantly less scatter.

At the radiometry laboratory of the Physikalisch-Technische Bundesanstalt a reflectometer for the soft x-ray spectral region is operated for several years utilizing monochromatic radiation from a toroidal grating monochromator or from a high resolution plane grating monochromator. The monochromators cover the photon energy region from 35 eV to 1500 eV. New challenges due to the development of soft x-ray optical components led to the design of a second reflectometer with advanced capabilities. Samples with a diameter of up to 250 mm can be accommodated. The time required for sample exchange is reduced by using a lock chamber. The feasibility of sample positioning with high precision has been improved. Typical uncertainties in the order of 1 - 2%, e.g. for the reflectance of multilayer mirrors, can be achieved. A detailed description of the reflectometer as well as some typical results showing the performance are presented.

During the manufacturing of grazing incidence X-ray optics telescopes having a large number of nested thin wall mirror shells, there is the need of making a first assessment of the imaging quality of each shell. The description of a possible test facility to realize these measurements is reported. It operates with the shell axis in vertical position, so to minimize the induced gravity deformation, and the radiation source is in the vacuum ultraviolet spectral region to limit the influence of the diffraction effects on the focal image. The mirror to be analyzed is fully illuminated by means of a collimator and the image at the focal plane is detected with a UV sensitive CCD camera. Moreover, the operation with a collimated light beam allows to make an assessment of the image quality of the fully assembled telescope: in this condition, all the useful area of the mirrors is tested. Some tests realized on a horizontal vacuum facility having the aim to validate this method are also described and the first experimental results are reported.

The Joint European X-Ray Telescope, JET-X, is one of the core instruments of the scientific payload of the Russian SPECTRUM-X astrophysics mission. JET-X is designed to study the emission from x-ray sources in the band of 0.3 - 10 KeV, particularly to meet primary scientific goals is cosmology and extragalactic astronomy. JET-X consists of two identical, coaligned x-ray telescopes, each with a spatial resolution of 30 arcsecond Half Energy Width or better. Focal plane imaging is provided by cooled x-ray sensitive CCD detectors which will combine high spatial resolution with good spectral resolution, with particular emphasis on high sensitivity and spectral resolution around the 7 KeV Fe-line complex. Each telescope is composed of a nested array of 12 mirrors with an aperture of 0.3 m and focal length of 3.5 m; the total effective area is 360 cm² at 1.5 KeV and 140 cm² at 8 KeV. The mirror shells have a Wolter I geometry and are manufactured by an electroforming replica process. The paper presents a status report concerning the development of the X-ray optics.

The flight version of the Objective Crystal Spectrometer (OXS) on the SPECTRUM-X- GAMMA satellite is presented. The spectrometer is a panel that is placed in front of one of the SODART telescopes. It is composed of an array of the three Bragg crystals, LiF(220), Si(111) and RAP(001) for high resolution spectroscopy in the energy bands that encompass the H- and He-like emission line features from the cosmically important elements Fe, S, Ar and O. An energy resolution (E/(Delta) E) of 1250 will be obtained for He-like Fe emission, > 3000 for He-like S and Ar, > 700 for He-like O. In addition, the Si crystals will be coated with a multilayer that will allow spectroscopy with an energy resolution of approximately 80 in the energy band immediately below the C-K absorption edge of 0.284 keV. All the flight crystals are available and detailed calibrations have been obtained for each crystal. They confirm our specifications for the overall performance of the OXS. An estimate of the effective area in the 4 energy windows that are available to OXS yields > 100 cm² from 5 to 7.4 keV, > 200 cm² from 2.3 to 4.6 keV, approximately 10 cm+2) from 0.55 to 0.81 keV and approximately 100 cm² from 0.175 to 0.28 keV.

The Optical Monitor is an ancillary instrument of the JET-X experiment on board of the satellite SPECTRUM-X-GAMMA. It consists of a Ritchey-Chretien telescope with an aperture of 230 mm, and two CCD detectors. The scientific objectives are the observations in the optical and UV band simultaneously with X-ray observations, the real time identification of X- ray sources with M_v <EQ 22 and detection of their variability, the improvement of the post-facto spacecraft attitude reconstruction (as a backup of the Attitude Monitor), and the serendipitous mode search for microvariability of the bright stars falling in the field of view.

The Spectrum-X-Gamma satellite is scheduled for launch in 1995-96. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from the EUV through hard X-rays with an emphasis on studying galactic and extragalactic X-ray sources. Timing and moderate resolution spectroscopy can be performed with the solid state spectrometer SIXA (Silicon X-Ray Array), placed on the focal plane of the SODART telescope with total effective area of 1150 cm² at 6 keV (for f equals 8 m telescope). The detector consists of 19 circular Si(Li) pixels, each with an active diameter of 9.2 mm and thickness of 3 mm. A radiative cooler will be used to bring the detector to the proper operating temperature (110 - 120 K). The energy range 0.5 - 20 keV is divided into 1024 channels of 20 eV size. Photon can be recorded with 30 microsecond(s) time resolution and 160 - 200 eV (1 - 7 keV) energy resolution. Potential observing programs (for e.g. time-resolved Iron K_alpha line spectroscopy) include stellar coronae, cataclysmic variables and X-ray binaries; accretion discs and coronae of neutron stars and black hole candidates; supernova remnants, active galactic nuclei and clusters of galaxies.

We report here on the design of the first crystal in an x-ray monochromator for ESRF beamlines. This crystal is a thin silicon foil bonded to a cooled beryllium support. A system of piezoelectric actuators is used to correct for the thermal deformations produced by synchrotron X-ray beams. The first step of this study is a thermomechanical simulation. It has showed that the slope errors of the crystal surface along the X-ray direction are less than 5 (mu) rad. The second step is a feasibility study of the silicon/beryllium bonding. After tests, we have chosen molecular adhesion method between the silicon crystal foil and the beryllium support.

In the industrial, medical and scientific market there is a great need for sensitive X-ray imagers for applications like non-destructive testing, medical imaging and fluorescence X-ray observation. This can be achieved with ICCD cameras equipped with a scintillator in front to convert the X-rays into visible light. In this paper two types of X-ray ICCD cameras are described which have their optimum sensitivities, respectively, in the soft and hard X-ray band. The energy band from 5 keV to 150 keV can be covered with these two cameras. Their performances will be compared with other types of X-ray imagers. A number of applications will be considered.

Development work on JET-X has been completed and the flight model instrument is under construction. The X-ray performance of the mirror system and of the CCD detector have been determined by measurement and simulation in the course of development and optimization of JET-X over the past two years. New data on fine structure in the spectral response of CCD quantum efficiency and mirror reflectivity are presented. These results indicate that low intensity synchrotron radiation is an important new tool in the calibration of X-ray telescopes and is essential for determining the fine structure in the spectral efficiency and spectral resolution of X-ray telescopes that use CCD focal plane detectors.

The XSPECT, thin foil, multiply nested telescope on SRG has been designed to achieve a large effective area at energies between 6 and 15 keV. The design goal for the angular resolution is 2 arcmin (HPD). Results of foil figure error measurements are presented. A ray tracing analysis was performed including results of earlier scattering measurements and the foil determination. The results of the analysis are compared with test measurements with X rays and show that there is a larger spread in the PSF than the model can account for. The decrease in effective area due to scattering is estimated to be 30% when the photons that scatter more than 6 arcmin are regarded as lost. The vignetting at off-axis angles leads to an effective area at the edge of the FOV which is 15% of that of an on-axis source.

IAS, a CNR institute for space research in Astrophysics, in collaboration with IKI on their invitation, has developed, and is now under building, an X-Ray Imaging and Spectroscopic telescope as the high energy instrument on board the Observatory Spectrum X-Gamma. The scientific aim of this instrument, named MART-LIME, will be the detailed study of X-Ray sources emitting in the energy range 5 - 150 keV. The MART-LIME telescope is a follow up in a series of X-Ray detectors that have been developed, built at IAS and flown on board stratospheric balloons. It consists of a high pressure gas operated multiwire proportional counter with bidimensional spectral resolution coupled with a coded mask placed at 2.3 meter.

We present preliminary results from a comprehensive program to calibrate the CCDs to be used as the focal plane detectors on the Joint European X-ray telescope (JET-X). The goal of the program is to calibrate the response of the flight CCDs (efficiency and energy resolution) down to a limiting precision of 1%. In addition to using conventional characteristic X-ray emission line calibration techniques to quantify the broad-band response, the devices have also been taken to the Synchrotron Radiation Source (SRS) at the Daresbury Laboratory to map the detailed X-ray Absorption Fine Structure (XAFS) around the silicon K-edge. To carry out the latter measurements, the SRS had to be operated with a ring current reduced by 5 orders of magnitude so that individual photons could be recorded by the CCD. The data show considerable near edge structure which is similar in shape to pure Si XAFS obtained by photocurrent measurements, but modified by the presence of the various oxide insulation layers used in MOS construction. Lastly, an analysis oft he pulse height spectra obtained at the SRS, has demonstrated that the Fano factor and the energy to create an electron hole pair vary with energy in agreement with the photoionization theory of Fraser et al. and the semi- empirical analysis of Owens et al.

Two SODART thin foil X-ray telescopes will fly on SRG. In the focal plane of one telescope there are: HEPC/LEPC (high- and low energy imaging proportional counters), SIXA (solid state spectrometer array), and FRD (focal plane X-ray detector). In the other, there are: another HEPC/LEPC pair, SXRP (stellar X-ray polarimeter), and another FRD. Mounted alongside and co-aligned with the SODART telescopes is TAUVEX (UV telescope). An objective Bragg spectrometer is mounted in front of one of the telescopes. These instruments and their scientific goals will be described briefly. More detailed discussions will be given by the relevant PIs in the poster session.

The low energy proportional counter LEPC (0.2 - 8 keV) and the high energy proportional counter HEPC (2 - 25 keV) for the Danish-Russian X-ray telescopes XSPECT/SODART are presently being tested at DSRI. The sensor principle of these detectors is based on the novel micro strip gas counter (MSGC) where the strip electrodes are deposited by photolithography onto a rigid substrate. The MSGC offers many advantages: A uniform gas gain, an excellent energy (approximately 13% at 6 keV) and position-resolutions (>> 1 mm), a fast charge collection and a low operating voltage. The energy response, imaging and background rejection performance of LEPC (82 X 82 mm) and HEPC ((sigma) equals 160 mm) will be discussed.

We have completed extensive synchrotron reflectivity measurements on several iridium mirrors which were intentionally coated with thin layers (100 angstroms or less) of polyethylene, a hydrocarbon contaminant. The purpose was to verify theoretical predictions of alterations in reflection efficiency of an iridium surface for various thicknesses of hydrocarbon contamination, and to evaluate the acceptability of attainable upper limits of such contamination for the mirrors aboard NASA's Advanced X-ray Astrophysics Facility (AXAF). Although the deposition of such thin layers is problematic with no systematic guarantee of uniform thickness or density, successful analysis by modeling the contaminant as a uniform surface layer may be done, within a limited X-ray energy range. The M-edges of iridium are significantly affected by the polyethylene layers. For the most part, contamination increases the reflectance in the M-edge range over that of bare iridium, although cross-over points between contaminated and uncontaminated mirrors occur at several angles relevant to AXAF. However, calibratability of the reflectance is a more significant issue than X-ray mirror efficiency. We present the modeling results for three thicknesses of polyethylene, and discuss the implications for the performance of AXAF mirrors and their calibratability.

MOXTEK and its collaborators have developed technology for the fabrication of multilayer soft x-ray diffraction gratings. The diffraction gratings we will discuss here are planar, or lamellar amplitude gratings, with a structure similar to that shown in Figure 1 . The gratings we have fabricated and measured consist of a silicon (100) wafer substrate onto which we spin photo-resist. The photo-resist is patterned holographically and the substrate is then etched using reactive plasma processing techniques. The period, or pitch of these gratings Is 0.293 jim, and the grating active area can be as large as 6 cm x 6 cm. The linespace relationship is approximately 50-50. The substrates are etched until the grooves are about 1 200 A deep. This Is done to place the bottom of the grooves deep Into the substrate where It will not be able to scatter x-ray radiation efficiently. A typical substrate is shown in Figure 2.

Charge Injection Device (CID) array detectors are well suited for the direct imaging with x- ray and particle beams. In common with CCD detectors, CID arrays have been shown to have good spatial resolution and broad spectral response in the visible range. In addition, CID imagers offer unique architectural features which may be particularly applicable to x-ray and particle beams, including exceptionally large pixel charge capacity, non-destructive pixel readout, and random pixel addressibility. These can dramatically extend the dynamic range, eliminate blooming effects, allow monitoring and dynamic adaptation of application exposure in real-time, improve signal-to-noise by repeated readout and permit the readout of small pixel sub-arrays at exceptionally fast rates. In addition CIDs possess extremely good radiation tolerance. Preliminary results of x-ray measurements with CIDs are presented along with a discussion of potential applications utilizing their unique features.

This paper discusses the performance of x-ray imaging devices employing optical coupling between the x-ray detector (phosphor screen) and the readout (CCD). Optical coupling can be performed with the aid of a lens or with the aid of a fiber-optic taper. Conventional wisdom predicts that fiber-optic coupling is superior on account of superior light collection efficiency. For the same demagnification, fiber-optic tapers usually have a higher numerical aperture in the object plane than a lens. This paper presents a review of critical imaging system components and provides a comparison of factors such as light collection efficiency, phosphor screen light output and CCD sensitivity. The paper presents data obtained with two commercially available x-ray imaging systems, one a lens coupled system, the other a fiber- optically coupled system. These systems are used for mammographically guided stereotactic breast biopsy to determine the x-, y-, and z-coordinates of the lesion to be biopsied. The paper concludes that a lens coupled x-ray imaging system can be superior to a fiber-optic one, particularly with respect to Detective Quantum Efficiency. This superiority is based on a quantum gain of about 5 CCD electrons per absorbed x-ray photon, which is (however barely) sufficient to preserve most of the information collected by the system's Lanex screen.