Using hot plasmas for making soft X-ray amplifiers will lead to laboratory sources brigther than any others by several orders of magnitude. Population inversions are produced either by collisional pumping due to plasma free electrons or by fast plasma cooling. Gain coefficients up to 5 per cm have been measured in the 100 A - 200 A range.

Recent developments at the Rutherford Appleton Laboratory on the use of 249nm KrF lasers for generating laser-plasma XUV sources are reviewed. XUV sources are produced using both a high energy (200J, 5Ons), purpose-built single shot laser and a low energy (0.7J, 25ns), repetitive(1 Hz) commercial system. These new sources have been applied to experiments in the areas of X-ray microscopy and X-ray lithography.

Intense x-ray generation in 1.053, 0.53, 0.26 µm laser-produced plasma has been investigated in the photon energy range of 0.1 to 3keV. The x-ray spectrum is found to have several humps which move to the higher energy side as the atomic number of the target increases. This atomic number dependence is explained by a semi-Moseley's law and allows us to predict a target material most suitable for generating the photons of desired energies. Conversion efficiencies of 1.5 rk, 3keV x-rays are obtained also as a function of laser wavelength at the intensity of 1013 W/cm2. The conversion efficiency of keV x rays has been enhanced by a factor of 2 % 3 with a controlled prepulse laser. From the semi-Moseley's law we find that cryogenic targets using either Xe or Kr in a liquid or solid phase may be most useful for a number of applications because they radiate 1 % 3 keV x rays efficiently and never deposit on the x-ray optical components and the objects to be exposed.

Measurement of the soft X-ray intensity emitted from the plasma formed by focusing a 20 Hz, 500 mJ Nd:YAG laser beam onto solid targets indicate that a similar soft X-ray source employing a laser with a repetition rate of a few hundred Hz will be suitable for scanning X-ray microscopy. At particular X-ray energies, the brightness of such a source is comparable to that from synchrotron sources such as the (non-upgraded) SRS at Daresbury.

The amplification of laser light in a free electron laser (FEL) due to stimulated bremsstrahlung in a traveling longitudinal undulating electric field is derived. It is shown that this FEL provides sufficient gain to be used as a coherent radiation source down to the soft x-ray regime. It is suggested that, among other possibilities, the wake-field produced in a two-beam elliptical or annular pill-box cavity is suitable for the required traveling longitudinal undulating electric field.

The technique of using two laser produced plasmas for absorption spectroscopy of ionic species has been greatly improved. A new signal detection system and a new data processing technique have been implemented in the experiment. This experimental technique has been applied to the absorption spectroscopy of transient moderately charged ions. The absorption spectra of the is electron of the Be IV, III, II, I ions with their relative photoionization spectra in the soft X-ray range are reported. Some preliminary results on the carbon ions are briefly discussed.

Schafer's PHILDEX-laser is a new scheme which consists in a cylinder-optical concentration of a short excimer laser pulse irradiating the high-Z coating of a cylindrical solid core of length £ and radius r. The pulse moves like a boots trap along the coating with nearly the speed of light. After 50% of the laser radiation is converted to X-radiation in the coating, this photo-ionizes preferentially the electrons in the lowest level of the core material. If nearly complete depletion with an atomic density n*(inverted states) is reached, the electrons at the energetically next higher level will decay to the lower level. For £» r, the preferential direction of the emitted superradiance along the axis will produce an X-ray laser pulse. For this laser some estimations are reported about the following properties: the line shift by recoil in the core which was assumed to be an instantly produced plasma where no Mossbauer-recoil is permitted. This is combined with the Doppler shift of the ionic motions. The overlapping of lines is found sufficient for the laser. An estimation of the necessary inversion density and the geometry of the medium are given. For the then necessary minimum core length of lmm, laser pulses in the order of 100 J are necessary with duration of less than 3 psec, preferably less.

The gas puff Z-pinch is an intense pulsed plasma X-ray source energized by a capacitor bank. Typically 5-10% of the electrical energy stored in the bank is converted into X-ray radiations with wavelengths less than 100 Å. Such devices have applications in X-ray microscopy, lithography, spectroscopy and X-ray optics engineering. Here we present the results of a parmetric study of the X-ray emission from a small gas puff Z-pinch which has 4kJ of stored electrical energy. The quantities measured are the soft X-ray emission in the wavelength range 4 to 85 A and the hard X-ray emission with wavelength less than 2.5 A. These quantities are found to depend on the gas used and the mass of gas imploded. Conditions exist that maximise the soft X-ray emission from the pinch. It is also shown that the hard X-ray emission can be reduced significantly by changing the anode material and by varying the mass of the gas imploded.

Laser created X-ray sources have been investigated both theoretically and experimentally using λ = 1.06 μm and λ = 0.26 μm and short pulses (0.5 nsec). Some preliminary results are given with UV radiation obtained with a long pulse (25 nsec) excimer laser. The con-version efficiency of the X-ray emission in the sub-keV (0.1-0.75 keV) and keV (0.75-2 keV) ranges is given for various atomic numbers and a large range of laser intensities. Using these results and resist sensitivities, we discuss the characteristics of the laser required for X-ray lithography.

We present results of preheat of thin foils heated by laser at 0.26 μm. The emission of the rear of the thin foils is imaged with the use of two Schwartzchild microscopes at 80 eV and 40 eV. These microscopes made of multilayered mirrors have a large aperture (f/2.5) and a good spatial resolution (5 μm) for a total reflec-tivity of about 1 %. The time integrated two dimensional images and time resolved images are shown. From the records at these two wavelengths we are able to deduce the temperature of the rear of the foils and its spatial distribution inside the heated surface of the foils.

Electron storage rings are the most effective sources of synchrotron radiation. The required extremely low beam emittance makes a very careful design of the beam optics necessary including the chromatic corrections. This adds nonlinear magnetic fields reducing the dynamic aperture for the beam. An example of low emittance optics is the modified Chasman-Green lattice of the ESRF. Synchrotron radiation with extremely high brilliance is produced by undulators and wigglers. These devices require special straight insertions.

Methods are presented for the determination of the vertical extension and divergence of electron beams in storage rings which also allow to obtain the vertical emittance. The ver-tical extension of the electron beam of the storage ring BESSY was measured with an X-ray slit camera. The vertical divergence was derived from the vertical angular distribution of the synchrotron radiation of the storage ring measured with either an X-ray polarimeter or an energy dispersive X-ray photon counter.

A spectroscopic method for the determination of the characteristic energy E_c of an electron storage ring is presented, which preferably can be used at VUV storage rings with E_c between 100 eV and some keV. With an energy dispersive photon counter (e.g. a Si(Li)-detector) the spectral photon flux of the synchrotron radiation around 20 E is measured with the intense low energy radiation cut off by filters. As the spectral photon flux at high energies strongly depends on E_c, the characteristic energy can be determined with a small uncertainty. For the electron storage ring BESSY E_c was determined with an uncertainty of 0.25 %. The result is in good agreement with the value of E_c determined from known electron energy W and magnetic induction B in the bending magnet.

Size, position and stability of the synchrotron radiation source BESSY are determined at present by imaging optical systems and wire monitors in the beamlines and by electrostatic position monitors in the storage ring. Since the size of the source has been brought down to FWHM-values Δ_y = 0.15 mm in vertical and Δ_x = 0.4 mm in horizontal directions for stored currents of I_R = 200 mA, the requirements with respect to the stability of position and size have increased considerably. Vertical position changes of 0.1 mm lead to apparent energy shifts of up to 100 meV on monochromators without entrance slits. Even when entrance slits are used, the intensity and degree of polarization of the radiation depend on the stability of the position of the source. All monitors in the beam lines and the monochromators themselves are sensitive to thermal expansion of their optical components. This means, that slow shifts occur during the life time of one filling of the storage ring and sudden shifts during each injection (between closing and opening of the beam shutters). Apart from these long time effects, flaring of the image of the source in the frequency range of a few Hz becomes visible on the optical system from time to time. In order to separate ring problems from beam line problems, such monitor systems are indispensable. Improvement of the monitors and measurements with a random access camera will be presented and discussed.

Present status of a beamline for a 60 period permanent magnet soft x-ray undulator inserted in the 2.5-GeV Photon Factory storage ring is described in detail. Two soft x-ray monochromators and a soft x-ray microscope installed in the beamline are also described. Design concepts of these instruments are presented and some remarks are made on their installations.

Direct on-axis time resolved measurements of undulator light have been taken with an x-ray streak camera on Beam Line V at SSRL. A UHV chopper, especially designed for high undulator power levels, was used to provide gating signals for the streak camera sweeps. A description of the system, as well as the results of the measurements and their preliminary interpretation, are presented in this paper.

The availability of undulators with submillimeter periods will profoundly affect the future development of soft x-ray sources and their attendant instrumentation. Outputs comparable to those of present-day conventional undulators, obtainable with much lower energy storage rings, is only one promising aspect of such devices. This paper critically examines some of the future prospects of such devices and describes the design and practical construction of a 1" long prototype consisting of 35 periods. A proposed experiment to test this device on a linac is described.

The off-axis angular harmonics of each spectral harmonic emitted by an undulator display a varying radial structure. In this paper we display such structures and provide a descriptive analysis For their maxima and minima.

Some general considerations for the application of mirrors in soft x-ray beamlines are reviewed and examples for state of the art mirrors are presented. In view of future light sources special attention is paid to deformation and damage of mirrors exposed to synchrotron radiation beams with high power densities.

Our laboratory is involved in fabricating imaging x-ray optics for both astronomical and laboratory applications. A large Wolter type I x-ray telescope is being fabricated as part of an x-ray spectrometer for observing the spectra of cosmic sources in the wavelength range from 8 to 30Å. The mirrors for this telescope are fabricated from blanks of 5083 aluminum alloy that have been figured by diamond turning. These figured surfaces are polished by applying a thin coating of acrylic lacquer that is subsequently overcoated by vacuum deposition of approximately 400Å of tungsten. This telescope is the imaging element of an X-Ray Objective Grating Spectrometer (XOGS) that uses reflection gratings for spectral dispersion and an image sensitive proportional counter to detect the dispersed x-rays. The XOGS will be flown on an ARIES rocket in the summer of 1987 to observe the soft x-ray spectrum of Sco X-1. The present status of the telescope will be described and some data from a preliminary test of the spectrometer at the Marshall Space Flight Center X-ray Calibration facility will be presented.

A 4nested mirror system of the Wolter I type has been developed in 3 steps. The optical qualification test was performed with a verification model (VM) for which a mirror pair was produced in the original size. For the mechanical and thermal qualification tests, the VM was extended into a structural thermal model (STM). The mirrors for the flight model (FM) and all mechanical structural elements have already been completed.

For the purpose of detecting tangent errors down to 0,1 arc sec on x-ray-mirrors, a computer controlled 3-axis coordinate measurement machine (CMM) has been developed which allows a position resolution of 10 nm in all coordinates. The concept of this CMM is based on the complete separation of machine controlling and measuring systems. Thus the measurements are not related the quality of machine axis but to the quality of reference mirrors which form normals for the three coordinate axes. Experiments performed until now show a reproducibility of better than 0,1 arc sec for linear measurements. Measurements of three dimensional structures are in preparation.

We have utilized a visible in situ ellipsometer to investigate the growth of oxide surface layers on aluminum and silicon films deposited in an ultra high vacuum (UHV system. A single molecular layer of oxide f%rms on the aluminum film surface in 1 hour when exposed to a partial pressure of 2 x 10^-8 Torr of either oxygen or water vapor. The single molecular oxide layer that forms in 4 hours on silicon when exposed to 2.5 x 10^-8 Torr of oxygen is Si or, if the vacuum ion gauges are operating, but it appears to be SiO if these gauges are turned off during the layer formation. The time of formation of these layers is inversely proportional to pressure. The growth rate of the oxide surface layer drops dramatically after formation of this first morolayer on both aluminum and silicon. Other gases, such as methane and carbon monoxide were found to be essentially urreactive with the aluminum film.

This paper describes the temperature gradients in multilayer optical thin films when subjected to soft x-rays. Equations are described for use in evaluating the time-temperature history of each coating interface and subsequent energy distribution to the substrate. One and three dimensional equations are provided to examine the impact of thermal diffusivity, relaxation time, and subsequent temperature rise in the optical thin films. Coatings that are supported by cooled substrates are evaluated as a function of substrate material and cooling medium heat transfer coefficient. Coating temperatures and substrate temperatures are evaluated for conditions satisfying the semi-infinite plate model.

This paper will describe a first order analytical technique for evaluating the Strehl ratio of a system composed of various optical components in a soft x-ray system. The basic elements of the model are to provide budgeting criteria that will permit the maximum energy in the central lobe of a far field distribution. Budgeting components will consist of figure error on the component, thermal distortion for transient and steady-state, pressure ripple for cooled substrates, and energy loss due to scatter and absorption in the coatings and the substrate.

Concave glancing incidence mirrors for deflection and turning of soft X-ray beams by large angles are considered. For carbon-coated superpolished concave mirror the reflectivity of 60% is measured for 6.76 rim radiation and turning angle T = 29°, which is two orders higher than for beam deflection by the same angle with one Fresnel reflection from a plane carbon mirror.

Grazing incidence telescopes have been in use for quite some time for X-ray applications. High resolution Wolter type I telescopes have been flown on board of Skylab, the Einstein and the EXOSAT satellites. ROSAT will he the next space borne observatory, which will perform for the first time a complete sky survey by means of a large high resolution grazing incidence X-ray telescope. The design and fabrication of the mirror assembly are presented including metrology measurements and full aperture X-ray tests. The X-ray image of the fully assembled prototype model shows a measured radius of 2.0 arcsec and 3.2 arcsec for the 50 (7.') and 80 encircled energy, respectively. Metrology measurements of the not yet assembled flight mirrors indicate an even better performance including microroughness of 2.6 Å rms. A cluster of highly nested Wolter type I telescopes has been proposed for ESA's future X-ray astronomy cornerstone mission XIM. The optical design of the mirror assembly optimized to high throughput but moderate re-solution is presented. Although originally proposed for X-rays grazing incidence telescopes start to be preferred for use at longer wavelengths due to the lack of high reflectivity coatings throughout the region from the X-rays to the UV at '- 1000 Å. The future UV astronomy mission Lyman selected for an industrial Phase-A study by ESA utilizes a Wolter. Schwarzschild type II telescope which feeds a high resolution (λ/Δλ = 30.000) spectrograph covering the 900 - 1200 Å region. The optical design of the telescope is described and the error budget for the manufacturing of the 1 arcsec telescope is discussed.

The objective transmission grating was one of the earliest inventions in the field of X-ray astronomy and has been incorporated into Skylab, HERO-P, and EXOTAT. In recent years there have been advances in grating technology and spectrometer design. A high precision mechanical ruling and replication process for manufacturing large self-supporting transmission gratings has been developed by an industrial manufacturer in cooperation with the Max-Planck-Institute (MPI). Theoretical analyses have determined the optimum configuration of the grating facets and the grating surface in order to correct third order aberations and obtain maximum resolving power. We have verified experimentally that the predicted efficiencies may be achieved. In addition, an experimental study of large grating assemblies for space telescopes was made in industry with scientific guidance by MPI. Main objectives of this study were the determination of mechanical loads during launch, as well as the design, construction and fabrication of a representative model of a ROSAT grating ring. Performancy studies including instrument pro-perties as well as the simulated radiation from hot plasmas have shown the ability of SPECTROSAT to perform high efficiency, high resolution line-spectroscopy on a wide variety of cosmic X-ray sources.

The different contamination control measures and monitors for the X-ray satellite ROSAT are described. Results are shown for cleanliness monitoring on ground and in vacuum test by Quartz Crystal Microbalance (QCM) and by analysis of witness mirror samples with Secondary Ion Mass Spectrometry (SIMS) and X-ray reflection measurements. Some unexpected contamination effects have had considerable impacts onto contamination control measures, especially onto specification of contamination witness samples, and they requested intense efforts with respect to contamination analysis. These investigations showed that there are considerable impurities of hydrocarbons trapped within the evaporated gold layers, caused by residual hydrocarbons in the evaporation facility or resulting from an unusually high affinity to hydrocarbon contamination compared to bulk gold. The latter may be stimulated by structural properties of the evaporated gold layer.

The high throughput of the ROSAT X-ray telescope is largely dependent on the reflectance of the gold coating of the mirrors in the wavelength region 6 - 100 Å. In this context measurements of the reflectivity and scattering of soft X-rays at various wavelengths and reflection angles have been performed on a large variety of flat mirror samples. The effects related to coating technique and surface contamination are discussed.

The Space Astrophysics Group at the University of California, Berkeley, is currently producing four grazing incidence mirrors for the Extreme Ultraviolet Explorer. In conjunction with this effort, we are developing improved methods for the evaluation of these mirrors' performance. Imaging and reflectivity analyses at optical and extreme ultraviolet (EUV) wavelengths allow us to quantify a mirror's performance with regard to effective area, surface roughness, and image blur. We present here the results from our most recent EUV measurements, and our latest techniques for evaluating the surface microroughness.

The Wide Field Camera (WFC) to be flown on the German satellite ROSAT is an XUV telescope operating in the energy band 12-250 eV utilising Wolter-Schwarzschild Type I grazing incidence optics. The design and performance testing of the mirror system are reported. In particular extensive reflectivity measurements made in the range 12-250 eV are compared with theoretical predictions and X-ray scattering measurements are used to assess the quality of the reflecting surfaces. Details of the testing and calibration of the combined mirror and detector telescope system are given showing that the performance is as expected from mechanical and optical metrology and that the telescope performance is within specification.

The crystal monochromator at BESSY covers the soft x-ray region above 800 eV up to about 5000 eV employing the (n,-n) double crystal arrangement with constant beam offset. Beamline and monochromator have been optimized for high flux and high resolution, and care has been taken to minimize radiation damage and temperature effects on the first crystal. The mono-chromator uses a novel mechanical linkage system for two simultaneous rotations and a translation and combines an effective homogeneous cooling of the first crystal with a simple in situ crystal exchange. Design features and performance data are presented.

Unwanted reflections, which are due to the structure of the crystal, cause glitches in the X-ray transmission of high resolution crystal monochromators. The wavelength at which the glitches appear depends on the orientation of the crystal. We show that by a slight rotation of the crystal in the plane facing the X-ray beam it is possible to cover a large energy range (5 to 14 keV) for EXAFS or XANES experiments with one set of crystals. The implementation in practice will be discussed.

The design of a new class of grazing incidence monochromator system is presented. The design uses a spherical grating in a simple rotation mounting with the non-dispersive focusing being accomplished with a separate focusing mirror. The characteristics of several configurations of the basic design are presented and the overall design procedures are discussed. The design is essentially free of aberrations and the principal degradation in resolution will be caused by tangential slope errors in the diffraction grating. The effect of the slope error on resolution is examined in detail. The design of an entrance slitless monochromator currently under construction at Daresbury is discussed.

We present a concept which describes the operation of BESSY plane grating monochromators in the two important modes: highest possible spectral resolution and alternatively very high spectral purity.

This paper describes a project to perform spectroscopic ellipsometry in the VUV and soft x-ray spectral range using synchrotron radiation.

Exploiting polarisation effects significantly adds to the information obtainable from spectroscopy. Espe-cially circular polarisation is needed in a large class of experiments including but not limited to angular and spin resolved photo electron spectroscopy, investigation of circular dichroism in chiral molecules, and magneto-optical effects. Many of those experiments have been limited to photon energies below about 9 eV due to the unavailability of quarter wave plates /1/. At higher energies with suitable lasers the range has been extended up to 15 eV /2/. Using the natural polarisation properties of out of plane synchrotron radiation, the region up to 35 eV photon energy is accessable /3/.

The recent development in grazing incidence grating monochromator design is discussed and the performance limiting factors for such instruments are examined. Especially the aberrations of toroidal and spherical gratings are investigated using the optical path function concept. It is shown that large radius spherical gratings, which can be produced with better slope tolerances than aspherics, also yield smaller overall line curvature than toroids. Therefore, a new simple spherical grating monochromator design is proposed and its performance is analyzed.

This paper reports on a set of interfacial structure studies in WC multilayers. Statistical investigations were conducted to ascertain whether building up layers containing, on the average, an integer number of atoms could in any way minimize the effects of interfacial roughness.

A review of optical systems for soft x-radiation 0.5 nm ≤ λ ≤ 4.5 nm is given. Grazing incidence and multilayer mirrors are shortly discussed. Zone plate fabrication methods and accuracy requirements are discussed and some aspects of holographic zone plate fabrication are described.

Two objectives to be used at 304 Å, in near-normal incidence have been made at IOTA : one is Ritchey-Chretien Telescope, the other is a Schwarzschild microscope used to observe laser heated targets. They are both made from two spherical surfaces shaped with an accuracy of λ/10, and covered by Si/Re-Wmultilayers. For the Ritchey- Chretien, the surfaces were aspherized by vacuum deposition before coating. Multilayer period and interface roughness were evaluated by using X-ray reflectanetry during the deposition process and grazing incidence X-ray reflectometry after the multilayer coating. A 7 A rms roughness for Si, 10 AÅ for W-Re, and a reflectivity of 10% were evaluated for each telescope mirror. For minimazing aberrations, the two mirrors of the Schwarzschild microscope were very accurateley centered. Results shows a resolution better than 4 gm for this instrument at the 304 Å wavelenght used.

X-UV multilayer mirrors have now been made and tested for about ten years , so it is the time to look if the initial hopes have been satisfied. These new mirrors have found applications in X-UV optical systems as Bragg reflectors alone, or combined with the grazing incidence mirrors and gratings. In this review paper we shall consider mainly the astrophysics, plasma physics and synchrotron radiation applications, the three fields for which the X-UV is an important range, to illustrate some kinds of problems which have been solved by using X-UV multilayered mirrors. Finally we shall try to indicate new promising directions.

Multilayer soft X-ray mirrors were deposited by using a triode dc sputtering system, equipped with an accurate method pf film thickness monitoring which enables the thickness to be controlled with an accuracy of better than 0.1 Å. Absolute reflectivity measurements of Ni-C and W-C multilayers at λ = 44.79 Å (c lea) in the first and second order Bragg Peaks, and at λ = 67.8 Å (B Ka) only in the first order were carried out. The incident beam is previously polarized by two parallel plane multilayer mirrors fixed at an angle close to Brewster's one ( 0 = 45°). Thus the measured reflectivitie are not affected by a progressive variation of the P component. The preliminary results obtained at λ = 113 Å (BeKot) are also presented.

A new basis is presented for the calculation of reflection coefficients of x-rays by multilayer artifacts. Thin film interference is treated at atomic plane level, using an iterative 2 x 2 matrix method. Analytic and computational comparisons are made with the conventional dielectric approach for TM and TE polarisations at non-normal incidence. Good agreement is obtained with recent accurate measurements by Evans.

We present measurements of diffraction peaks from six different multilayers of W/Si, Ni/C and ReW/C-layering. We have used FeKa-radiation and a three-axis, perfect crystal, x-ray diffractometer. The measurements suggest that these multilayers do not suffer seriously from imperfections. Improper estimates of the relative layer thickness of the two components may be as important as imperfections for these multilayers. All the multilayers studied show mosaicity which would be expected to originate in the substrate.

We describe the fabrication procedure as well as results of an extensive series of characterization measurements, model-fitting and synchrotron tests on Si/W multilayers designed as normal-incidence reflectors for -200 Å radiation. Characterization techniques used were low-angle diffraction, Bragg-Brentano and Seemann-Bohlin diffraction, Read camera, transmission electron microscopy and Rutherford backscattering spectroscopy. To our knowledge, this is the first time such a comprehensive set of characterization techniques has been applied to a multilayer x-ray mirror. Reflectances for -200 Å calculated using the results from these various characterization techniques are found to agree very well with measurements obtained with synchrotron radiation.

In the energy region between 400 and 900 eV the performance of monochromators based on both gratings and inorganic crystals is poor with respect to that in other regions, so that there has been speculation on the role that multilayers can play. We report results of characterization of a double "crystal" monochromator for synchrotron radiation in the region of 200 - 900 eV in which two Ni/C multilayer coatings (2d = 62 Å) are used. The energy resolution is measured to be about 75 by reflection measurements with a KAP crystal and by recording absorption edges and "white lines" of 3d transition metals. The potential of multilayer coatings is further illustrated by measurements of reflection profiles of other ReW/C coatings. We also report results on a second approach in which a double "crystal" monochromator is equipped with an organic crystal (KAP) preceded by a single multilayer with a layer thickness matched to the 2d-spacing of the organic crystal. This arrangement is shown to protect effectively the organic crystal from radiation damage and to give an energy resolution of about 1000, although the reflectivity is low. The use of multilayers in other concepts to mono-chromate synchrotron radiation is also discussed.

5 cm diameter, plane multilayer mirrors of different 2d value, have been fabricated from polycrystalline platinum and amorphous carbon. The performance of these multilayers as a function of layer number and thickness is presented. The importance of the commensurate nature of the stack in determining the Bragg reflectivity values (typically greater than 40% at wavelength 0.834nm) is described with reference to TEM photographs and resistivity measurements.

A lacquer-coated, diamond turned Cu ellipsoid has been used to micro-focus undulator light from Beam Line V at SPEAR down to a half-power diameter of about 13 microns. This spot was source-size limited, as has been demonstrated with ray tracings of the optical system. The symmetry of the image, as well as its size and power density, clearly make this optic ideal for many soft x-ray applications, in particular for x-ray microscopy, microprobes, and for pumping soft x-ray transitions in various media.

We have been developing ultrathin multilayered films to serve as radiation entrance windows and spectral filters in satellite borne position sensitive proportional counters for imaging ultrasoft X-rays from celestial sources in the wavelength region 0.6 < X < 10 nm. The performance data being measured will be given.

Diode RF sputtering technique has been used to produce carbon-tungsten ultra thin layers stacks for application in the soft X-ray domain as optical system. In situ kinetic ellipsometry has been chosen to control the multilayers growth with a great accuracy. Grazing X-ray reflection (1.54 P., absolute soft X-ray reflectivity (44.7 Å) and cross section transmission electron microscopy results confirm a posteriori the ellipsometry ones. Deposition conditions have been optimized using these characterizations. The thick-ness fluctuations are very low (0.2 % per layer). We have observed the smoothing of the layers roughness as the number of C-W sequences increases (the substrate having a roughness of 7 Å, the layers of 2 Å). We have realized multilayers in the range 2d = 60 Å and 2d = 90 Å. Their reflectivities typically reach 8 % = 45° at 44.7 Å) for the first ones and 13 % (9- = 30° at 44.7 Å) for the second ones. We have also realized stacks with a great number of layers in the range 2d = 100 A. 17 % reflectivities have been reached for a 180 layers stack.

To reach the theoretical performance of the new generation of artificial X-ray and X-UV Bragg reflectors, it is necessary to improve the layering qualities of the various deposition methods and the accuracy of measurements of the parameters of the produced stack. Such layered structures are not exclusively X-rays optics oriented: microelectronic and optoelectronic devices rely on superlattices structures. Such layered structures, both crystalline and amorphous, are now investigated in other fields of physics because their quasi bidimensional structures give rise to new possibilities in such field as magnetism and superconductivity .

In an effort to make data on the reflectivity and transmission of multilayer optical elements more usable, we have developed a computer code for the manipulation and graphical display of a general data set consisting of x, y, and delta-y values. The code was developed for a DEC VAX computer running a version 4.2 or later VMS operating system. Facilities are available for algebraic manipulation, editing, smoothing, interpolating, and deconvolving data sets in a straightforward way. The code is entirely self-contained with the exception of the graphics output support, which is centralized to allow for simple interfacing to the graphics package resident on the target system. The capabilities of the code are described and sample output is shown.

Many promising applications of multilayer x-ray optical elements subject them to intense radiation. In this paper we present simulations of multilayer performance under extreme heat loads and preliminary results of robust multilayer characterization experiments.