We report here the development of a hard x-ray multilayer grating that has achieved an absolute efficiency of 34% at a wavelength of 1.54A. The W-C multilayer itself has a reflectivity of 57% and the grating has a 0th order absolute efficiency of 36%. The origin of this extraordinarily high efficiency is that the short period and highly asymmetric structure of the grating combined with its deep grooves allows light to interact with a large number of layer pairs. This increases angular separation of the diffraction orders and reduces the multilayer bandwidth to the point where there is little or no order to order overlap in the grating structure, and hence maximum intensity can be diffracted into a selected order. This paper reports on the development of an optimized multilayer grating and some of its unique characteristics.

We present new experimental data on diffraction efficiency measurements on gratings for the first undulator beamlines at BESSY II. The measured data will be compared with results from electromagnetic theory. A good suppression of higher orders, i.e. the sum of higher orders from higher energies which are diffracted into the same angle as the first order, has been an important point during the design process of the beamlines at BESSY II. For this purpose lamellar grating structures have been optimized and specified. The measurements were carried out with a triple axis vacuum diffractometer at the BESSY I PM 4 beamline in an energy range from 70 to 1200 eV. We measured the diffraction efficiencies of the first order and the corresponding second and third order at discrete energies E, i.e. second and third order efficiency at 2E and 3E respectively. To improve the accuracy of the measurements, the higher orders from the PM 4 beamline had to be taken into account. We used a calculation scheme starting at the highest energy, in which the diffraction efficiency of the grating under test and the higher orders from the monochromator have been evaluated simultaneously. The calculated higher orders of the monochromator were then recursively used as input for the calculation at lower energies. The gratings were measured at different angular settings, hence enabling different degrees of high order suppression. It was determined, that with appropriate angular settings, the higher orders of monochromator gratings can be significantly reduced.

We report about the diffraction efficiencies of two new types of multilayer diffraction gratings, one of them being proposed for high spectral dispersion ability due to a high line density in the photon energy range around 90 eV, while the other is being proposed as a multilayer grating working in the water window spectral range around 470 eV at near normal incidence angles. For a 6600 L/mm sinusoidal interference grating coated with 18 Mo/Si doublelayers of d = 8.2 nm absolute diffraction efficiencies up to 11 % at a wavelength .\ = 13.2 nm were measured in each first diffraction order. A 2400 L/mm laminar grating was coated with 60 Ti/C bilayers of d = 2.2 nm for high efficiency in the water window spectral range near the Ti-L edge (.\ = 2.77 nm). For a similar Ti/C multilayer mirror refiectivities of 11 % were measured at a wavelength ) = 2.7 nm and an angle of incidence a = 59 deg. First order diffraction efficiencies of about 0.7 % were measured for the Ti/C multilayer grating.

A design method, called the hybrid design method, is applied to the design of(1) a zero-dispersion and constant-devialion type doub1egrating predisperser system for a VUV high-resolulion off-plane Eagle spectrometer which utilizes a high-order spectrum and (2) a wide-aperture Wadsworth4ype VtJV imagng spectrograph which consists of aspheric mirror and grating. The gralings of these systems are holographic gralings recorded with aspheric wave fronts. The results Obtained show the effectiveness of the hybrid design method and the versatile applicability ofa holographic grating recorded with asphenc wave fronts.

Efficiency, scattering, and spectral resolution measurements were made on two equivalent varied-line-spacing plane (VLS) gratings with a central groove density of 1200 1/mm, one a blazed grating made by mechanical ruling and the other holographically recorded and ion etched to a laminar groove profile. The line spacing variation of the holographic grating was obtained by interfering a plane wave and a spherical wave. Both gratings were designed to be used in the monochromator of the Calibration and Standards beamline built and operated by the Center for X-ray Optics at the Advanced Light Source, and all measurements were made efficient in the 600-850 eV region but more efficient below 600 eV and above 850 eV. Substitution of the holographic grating into the beamline extended the energy range from 1000 eV to 1300 eV. The holographic grating exhibited considerably less scattering, but its spectral resolution was lower at an energy of 400 eV. It is likely that this resolution can be improved by adopting a holographic recording system which employs interference of a plane and an aspheric wave.

The achievement of high resolving power from VUV to soft X-rays is a new challenge for synchrotron radiation beam-lines. When the X-UV range has to be privileged, we show that an optimized Plane grating monochromator (PGM), which can be corrected up to large aperture angles, offer a good compromise between resolution, flux and easiness of use. The design method and especially the determination of deviation angles and gratings parameters are outlined. The dependence of ultimate performances on the fabrication accuracy is evaluated; This design is compared to an alternative SGM design and their performances are found complementary.

A new grazing incidence soft x-ray monochromator has been commissioned on the undulator beamline BL-2 of the Photon Factory. The monochromator has been designed to meet the demands for high-resolution soft x-ray spectroscopy. The monochromator has employed a varied space plane grating and a configuration with sagittal focusing and converging beam to satisfy the requirement. According to analytical estimation and ray tracing simulation, the high resolving power beyond 10000 can be obtained over the full energy range from 250 to 1400 eV. Preliminary experiments have been done on three points concerning the resolving power, photon flux, and spot size. The results have showed the typical resolving power from 7500 to 10000, the absolute photon flux ofthe order of lOb photons/s/300mA/O.02%BW, and the spot size ofO.1(V) x 0.9(11) 2FW at the sample position.

The materials science beamline (MSB) is to be attached to a bending magnet ofthe Elettra storage ring. The tuning range of the materials science beamline is from 20 to 1000 eV with the spectral resolving power c/Ar better than 4000 in the whole tuning range. Optics of MSB consists of the polarization aperture, toroidal prefocusing mirror, entrance slit, plane premirror, single plane grating, spherical mirror, exit slit and toroidal refocusing mirror. The plane grating is operated in the fixed focus mode with C11 2.25. The choice ofdistance entrance slit - plane grating and Callowed to suppress entirely the coma aberration of the spherical focusing mirror. The scanning of the light wavelength is done by rotation of the plane grating and by simultaneous translation and rotation ofthe plane prernirror. Translation and rotational movements ofthe plane premirror are mechanically coupled by means ofa cain. The expected beam spot at the sample has a size ofO.06x0.O1 mm2 (cx) approximately. The expected photon flux at the sample is 3x10'° photons/(s 0. 1%BW) at 1000 eV and I x1012photons/(s 0. l%BW) at 20 eV.

In the past few years a number of variable angle spherical grating monochromators (VASGM) have been proposed and installed at Elettra beamlines. At present one of them (ESCAmicroscopy beamline) is operating, two (Spectromicroscopy and GasPhase photoemission beamline) are under commissioning, and one (Circulary Polarized Light beamline) is under construction. Although the experimental requirements of these monochromators are different, their control principles are the same. Approximately one year ago we started a project that aimed to provide a uniform and adequate system for controlling these monochromators. The paper deals with several frameworks of this project. First the monochromator software architecture is explained whereby the monochromator high level application options are explained. Instead of using extensive look up tables for the relationship between the energy and the angles of the mirror and gratings, we tried to develop an on-line mathematical model for energy tuning. An interesting feature of this model is that all monochromator data are parametrized which is important for the monochromator calibration. Much effort has been spent in order to understand the drive unit positioning behavior in the submicron scale which is non linear as a function of motor steps. As a result of this study some common drive unit mechanical properties were fixed according to which an absolute drive unit positioning control software is proposed. Finally we discuss some topics regarding the monochromator calibration and resolution optimization.

A Variable included Angle Spherical Grating Monochromator was installed on beam line at ELE1TRA in Italy. This unique monochromator is capable of high resolving power. For certain combinations of energy range and grating, resolving powers in excess of 20,000 are theoretically possible. To achieve these high resolving powers, precise mechanical alignment of all internal components is a necessity. Parallelism of rotation axes and optical surfaces must be better than 10 arc seconds, and position errors in locating components are required to be in the range of 10 microns. During the final alignment of this monochromator on the beam line, it was found to have errors 50 times larger than the specifications. Realignment of the internal components was necessary to improve the instrument performance. A penta-prism method was suggested and an autocollimator test method was used to correct parallelism between components in the monochromator while on the beam line. However, it is recommended to prealign and check the monochromator accurately in the optical metrology laboratory prior to the final beam line alignment. This two-stage procedure will ultimately save time and allow the beam line to achieve the highest possible performance in the shortest amount of time.

The definition of the generalized optical path function for a grating or mirror with a single plane of symmetry is reviewed. The generalized optical path function is then expanded in a series of wavefront aberration terms using only a few lines of code in the MathematicaTM scientific programming environment. The use of the algebraic capabilities of the MathematicaTM environment allows straightforward calculation of aberration coefficients that would normally require considerable effort if undertaken by paper and pencil. In addition, the derivation can be carried out to higher order aberration terms, limited only by the capabilities of the computer platform used.

The application of ray deviation calculations based on aberration coefficients for a single optical surface for the design of beamline optical systems is reviewed. A systematic development is presented which allows insight into which aberration may be causing the rays to deviate from perfect focus. A new development allowing analytical calculation of lineshape is presented.

Laminar groove profiles promise a high suppression factor for the even orders of reflection gratings. For normal incidence mounts the theoretical suppression of the second order should be nearly perfect if the groove to land ratio of 1 : 1 is matched. Experimental experience with laminar gratings demonstrates that the suppression of the second order is not as good as expected from calculations. Once we understood that the behaviour of the second order contribution cannot be explained in terms of a mismatch of the groove to land ratio alone, we started to investigate the characteristics of laminar groove profiles in more detail by means of atomic force microscopy. The main discrepancy between the idealised laminar profile and the measured profiles is the limited aspect angle of the edges of the grooves: the profiles are rather trapezoidal than laminar. Simulating the diffraction efficiency of the measured trapezoidal profiles revealed that the shallow aspect angle has a significant influence on the higher order diffraction efficiencies. Optimising groove profile parameters under assumption of a realistic aspect angle yielded essentially different values than the same procedure for idealised laminar profiles.

The performance of a beamline containing a blazed and a laminar grating is reported in this paper. Two varied line spacing (VLS) gratings are currently installed in the SRC High Energy Resolution Monochromator (HERMON). The blazed grating was ruled on a conventional ruling engine. The laminar profile grating was created holographically. The grating blanks were cut from a single spherical substrate having a figure error of less than 0.2 arcseconds RMS. The theoretical resolving power of 5000 to 10000 has been achieved in the energy range of 245 to 550 eV for the medium energy grating and 500 tol 150 eVfor the high energy grating indicating correct application of the polynomial groove density to the gratings. The groove profile for the laminar grating has been measured using atomic force microscopy and is in agreement with specifications. The beamline achieves near theoretical throughput throughout its scan range. A third grating which was designed to be blazed and ion etched is currently being evaluated.

For the design and characterization of synchrotron monochromators in the XUV region it is advantageous to know the performance of the mirrors and gratings as exact as possible within the wavelength range of operation to get performance results under realistic conditions. For that reason, monochromator gratings for dipole radiation as well as for undulator radiation at BESSY II are investigated in their wavelength range of operation by two different methods of electromagnetic grating theory. The IESMP, developed at BIFO, is a special boundary integral method, while the other, LUMNAB, developed by M. Nevière and available at BESSY, is based on the differential equation method. Both methods are compared with measurements on a plane grating in fixfocus condition for an energy range from 150 eV to 1000 eV. The observed differences between both methods and between the numerical results and measurement are discussed. For a grating monochromator in a variable included angle scheme efficiencies from the IESMP calculations for the first and higher orders are compared with scalar theory. Because of significant differences in the predictions of both methods this has to be verified by measurement.

For the high brilliance synchrotron radiation source BESSY II a couple of systems performing microscopy and spectromicroscopy at both high spatial and high energy resolution are planned or already under construction. The desired spatial resolution is in the nm-range, and thus monochromators are required which conserve the brilliance of the source throughout the beamline onto the analysed area. To serve the ultrahigh-resolution spectromicroscope SMART, a Petersen monochromator will be installed at an insertion device of 49 mm period length. When operated in highest spatial resolution mode, the field of view of the microscope is about 5 jtm in diameter. To optimize the photon flux density in the microscopes field of view, we studied the performance of the Petersen monochromator for various horizontal demagnification factors. The resulting optical layout produces a monochromatic image of the undulator source on the sample surface, which has a horizontal size of about 9 pm full width at half maimum. The vertical size of 5itm is determined by the exit slit width.

Third generation synchrotron radiation light sources are designed for the operation of undulators and wigglers which increase the brightness by several orders of magnitude compared to dipole radiation. The light is partially coherent - and diffraction effects, depth of field effects of the insertion devices and polarization characteristics should be taken into account for beamline design and for radiation characterization. In previous work a procedure for a wave-front transformation through synchrotron radiation beamlines has been derived. The code PHASE allows a detailed description of diffraction related problems. In this paper an improved integration algorithm for the transformation method is presented which reduces the cpu time by one order of magnitude. Furthermore, a stepwise transformation of the wave-front is introduced which makes possible the evaluation of the electric field distribution at the surface of an optical element and hence, the implementation of apertures, random slope errors or refiectivities.

A Varied-Line-Spacing (VLS) plane grating for the Monk-Gillieson mounting monochromator was fabricated with aspheric wavefront holographic recording following a new design concept. Ray-tracing results show that the holographic VLS grating affords high resolving power as a total optical system of a soft x-ray grazing incidence monochromator. Effects of errors in the recording parameters are also estimated, and the adjustment procedure to compensate for them was proposed. An 800-L'mm holographic laminar VLS grating has been tested in a new monochromator installed at a bending magnet source of the Photon Factory, and the resolving power of -..5OOO was obtained in the vicinity of nitrogen K-edge. It was found that the holographic grating has a relatively high reflectivity with a low scattered light level.

A novel kinematic mount system for a vertical focusing mirror of the soft x-ray spectroscopy beamline at the Advanced Photon Source is described. The system contains three points in a horizontal plane. Each point consists of two horizontal linear precision stages, a spherical ball bearing, and a vertical precision stage. The horizontal linear stages are aligned orthogonally and are conjoined by a spherical ball bearing, supported by the vertical linear stage at each point. The position of each confined horizontal stage is controlled by a motorized micrometer head by spring-loading the flat tip of the micrometer head onto a tooling ball fixing on the carriage of the stage. A virtual sine arm is formed by tilting the upstream horizontal stage down and the two downstream horizontal stages up by a small angle. The fine pitch motion is achieved by adjusting the upstream stage. This supporting structure is extremely steady due to a relatively large span across the supporting points and yields extremely high resolution on the pitch motion. With a one degree tilt and a microstepping motor, we achieved a 0.4 nanoradian resolution on the mirror pitch motion.

Construction of the high-resolution soft x-ray spectroscopy undulator beamline, 21D-C, at the Advanced Photon Source (APS) has been completed. The beamline, one of two soft x-ray beamlines at the APS, will cover the photon energy range from 500 to 3000 eV, with a maximum resolving power between 7,000 and 14,000. The optical design is based on a spherical grating monochromator (SUM) giving both high resolution and high flux throughput. Photon flux is calculated to be approximately 1012 1013 photons per second with a beam size of approximately 1 x 1 mm2 at the sample.

In this paper we discuss the design and anticipated optical performance of a multilayer spherical grating monochromator for x- rays with energies of 1-4 keV. The monochromator is to be used for x-ray microscopy and coherence experiments on the 2-IDB soft x-ray beamline at the Advanced Photon Source. The layout, design considerations, and resolving power with various single and multilayer grating coatings are discussed.

The new beamline ALOISA is now working at the Elettra synchrotron facility. It is equipped with a monochromator of new design to cover the 200 eV - 8 KeV energy range: the monochromator has two interchangeable dispersive systems, one for the low energies up to 2 KeV using reflection gratings and another with crystals for the higher energies. The monochromatic beam is finally re-focused from the fixed exit slit to inside the experimental chamber by a toroidal mirror. In this paper the results of the first resolution measurements are reported for the low energy section of the monochromator: a resolving power higher than 5000, with peaks of 10000 in the 400 - 500 eV region, is obtained while using all the optical elements at full illumination.