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Issue 12 ， 2007
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Application of a monolithic polycapillary X-ray lens in EXAFS experiments
Abstract：The performance of the Monolithic Polycapillary X-ray Lens (MPXRL) for application in the Extended X-ray Absorption Fine Structure (EXAFS) technique is reported, especially, the main characters of the MPXRL such as gain in flux density, stabilizing effect, and high energy filtering. Experimental results show that the spatial resolution of the EXAFS facility based on the MPXRL is about 25 μm, and the gain in flux density of the Monolithic Polycapillary Focusing X-ray Lens (MPFXRL) is about 3 000 when the MPFXRL is used to focus the laser plasma pulsed X-ray for ultrafast time-resolved EXAFS experiments. These indicate that the MPXRL is helpful in the improvement of the EXAFS facilities.Keywords：capillary X-ray optics;EXAFS;micro-EXAFS;ultrafast time-resolved EXAFS- 31
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Published：2020-08-12 -
High-resolution diffraction X-ray optics
Abstract：A review of different diffraction optical elements developed at BESSY for X-ray focusing is presented. Bragg-Fresnel optics as a basic element to design effective and high resolution X-ray focusing and dispersive X-ray optics is discussed. An experimental investigation of the combination of a long focal distance Bragg-Fresnel lens with a bimorph mirror is described. A reflection Fresnel zone plate has been tested as a focusing and dispersion optical element for X-ray Absorption Spectroscopy (XAS) on short-time pulse beamline.Keywords：diffraction optics;Bragg-Fresnel optics;zone plate;synchrotron radiation- 24
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Bent crystal X-ray optics
Abstract：Much effort has been exerted both in the development of modern dedicated synchrotrons and free electron lasers with unique properties. Femtosecond laser plasma sources provide ultra-short X-ray pulses of high peak brilliance and can thus be complementary X-ray sources to the undulator based sources. All these modern X-ray sources need dedicated X-ray optics for diagnostics and applications, respectively. X-ray spectroscopy is one of the most important diagnostics of plasmas in the context of laser fusion. Depending on the aims of these experiments, monochromatic X-ray images or high resolution spectra combined with either spatial or time resolution can be obtained. Sophisticated monochromatic imagers with up to 10 toroidally bent crystals have been developed to study the implosion processes in laser fusion experiments; time-resolved maps of plasma parameters are evaluated from the data.High-power femtosecond lasers provide a practical, relatively inexpensive, powerful X-ray pulse source. Information on production efficiency, the energy distribution and transport of hot electrons is needed to maximize X-ray output in desired K-shell emission lines or continuum ranges so that peak brilliances comparable to those of synchrotrons may be feasible. Combining these new sources with bent crystal optics enables diffraction experiments on sub-picosecond time scales. Laser-pump X-ray-probe experiments have shown evidence of structure changes in several crystals within 250 fs. These X-ray optics have been designed in our institute using ray tracing and Bragg reflection codes for the 1D or 2D bent crystals or combinations thereof. In the preparation process, extreme care has been taken over crystal perfection, selection of optimum reflections, precision bending, measurement of imaging and reflection properties. X-ray topographic cameras and diffractometers are used to check the relevant properties of the analyzer crystals.Keywords：X-ray optics;bent crystal;X-ray diagnostics;laser produced plasma;X-ray diffration- 29
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X-ray radiometry
Abstract：Source-based and detector-based radiometry has been realized in the X-ray range during the last few years by using synchrotron radiation. Electron storage rings are operated as primary source standards and cryogenic Electric Substitution Radiometers (ESRs) as primary detector standards. As ESRs require intense monochromatic radiation, synchrotron radiation is also necessary for this approach. Energy-dispersive detectors as well as silicon photodiodes have been calibrated with relative uncertainties of the detection efficiency or responsivity down to about 1%. The results are compared to model calculations.Keywords：X-ray radiometry;synchrotron radiation;radiation source;Detector- 60
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Characterization of low-Z material layer profiles in bilayer structures by X-ray reflectivity measurement
Abstract：A convenient method,low-angle X-ray reflectivity measurement method, is presented to characterize the parameters of low-Z material layers in bilayer structures using X-ray diffractometer (XRD). Because the low-Z material optical constant is similar to the silicon (Si) substrate, the change of the low-Z material layer profiles is difficult to determine.Therefore, an ultra-thin metal layer is deposited as the Base Layer (BL) onto the substrate prior to the low-Z material layer. By choosing chromium (Cr) as the BL material, three Cr/C bilayer films with different C deposition times are fabricated and measured. After the simulation of the reflectivity curves, the density of C is approximately 2.25 g/cm3, while the deposition rate of C layer is 0.058 nm/s under our laboratory conditions.Keywords：XRD;low-Z material;reflectivity measurement;thin films- 48
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Design of VUV beamline for ARPES studies at SSRF
Abstract：Vacuum ultraviolet (VUV) beamlines have been playing an important role in studying the electronic structure of solids. Until now, over 30 VUV beamlines for Angle-resolved Photoemission Spectroscopy (ARPES) studies have been built in the synchrotron radiation facilities of US, Japan and Europe. In this work, we present a design of a high-resolution and high-flux VUV beamline covering 5~140 eV photon energy range at Shanghai Synchrotron Radiation Facility(SSRF) for ARPES studies. A quasi-periodic Elliptical Polarized Undulator (EPU) with 14 periods and each 0.32 m long is used as the source. A Dragon-type monochromator with two branches, a lower energy branch covering 5~32 eV and a higher one covering 25~140 eV, is employed. Calculations show that the total resolutions of the monochromator can reach up to 15 000~100 000 with entrance/exit slit openings of 5/5 μm and the ultimate flux of the s-polarized photon on a sample exceeds ~1012 phs/s. The figure slope errors dominate the total resolution limit of the monochromator. Ray-tracing simulations show that the designed beamline has a good focusing performance. This beamline will be the first VUV beamline constructed at SSRF and will provide valuable experience for future constructions.Keywords：beamline design;VUV;high resolution;high-flux- 49
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Multilayer-based soft X-ray polarimetry
Abstract：An overview of the soft X-ray polarimetry udertaken at BESSY over the last 10 years is presented. At BESSY, ten elliptical undulator beamlines are operating in the VUV and soft X-ray range, which enables the polarisation state of the synchrotron radiation to be changed from linear (horizontal or vertical) to left- or right-handed circular. It is essential that the degree of polarisation is known quantitatively, since this is a normalization quantity for many polarisation-sensitive experiments (e.g. MCD-spectroscopy). For a polarimetry experiment i.e. the measurement of the polarisation state of light, two optical elements are required acting as a phase retarder and a linear polariser, respectively. In the soft X-ray range, specially tailored multilayers (ML) operating in transmission and in reflection have been developed and optimized for this purpose. By matching the ML-parameters (period, thickness ratio) to an absorption edge of one of the constituent materials, a resonantly enhanced polarisation sensitivity can be achieved. Thus, ML-polarimetry is strongly connected with At-Wavelength Metrology of these polarisation optical elements, for which the instrumentation and results are presented.Examples of magneto-optical spectroscopy and polarimetry to determine properties of magnetic thin films or optically active substances are also presented (Faraday and Kerr effect, L-MOKE).Keywords：Multilayer;soft X-ray radiation;EUV radiation;synchrotron radiation;polarimetry;linear analyser;phase plate;reflectivity;magneto-optic instrument- 28
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Published：2020-08-12 -
Soft X-ray and extreme ultraviolet optics in CIOMP
Abstract：Some key technologies on soft X-ray and Extreme Ultraviolet (EUV) optics developed at CIOMP are reviewed in this paper. The technology for laser-produced plasma sources is described and a laser-produced plasma source with a liquid target worked at wavelength range of 6~22 nm has been developed. Soft X-ray and EUV photon-counting imaging is introduced and a two-dimensional photon-counting detector with position sensitive anode is fabricated. The active area of the detector is 25 mm in diameter and the resolution is 0.3 mm. The technology of super-smooth mirror fabrication is studied and a polishing machine has been developed to fabricate the super-smooth surface mirrors with the roughness and the figure of 0.6 nm (RMS) and 6 nm (RMS),respectively. Soft X-ray and EUV multilayer film technologies are coverd also in the paper and a number of mutilayer coating mirrors have been deposited for some space science projects. These multilayer mirrors show their reflectivity of 60% at 13 nm and the uniformity better than ±2.5% across a 150 mm diameter. The soft X-ray and EUV radiometric technologies are studied and a reflectometer, with operational wavelength range of 5~50 nm, spectrum resolution of 0.2 nm and repeatability better than 1% has been set up. Based on a cutting-edge technology, an EUV imager and a space EUV solar telescope are developed,these imaging instruments have played an important role in a number of scientific projects.Keywords：space optics;Soft X-ray;EUV- 49
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Large X-ray optics: fabrication and characterization of single and multilayer mirrors
Abstract：Various X-ray optics with an optical length of 150~500 mm are employed for beam guidance, beam alignment and monochromatization. This paper focuses on two different types of large X-ray mirrors. The first optical element is a single-layer mirror which works as a total-reflection mirror in the soft X-ray range (50~200 eV) and at a grazing incidence angle of 2°. Such a mirror is used in free-electron lasers, e.g. FLASH in Hamburg, Germany. The second mirror is a multilayer mirror, which is employed as a reflector due to its Bragg reflection for the hard X-ray range (20~50 keV) and at incidence angles of 0.4~1°. Such a mirror could be used at a synchrotron storage ring, for instance in a tomography beamline. In both cases, the mirrors are fabricated by means of state-of-the-art physical vapour deposition techniques, using magnetron sputtering to achieve a good optical quality for their X-ray optical application. This deposition process allows good run-to-run stability, which is crucial for the final deposition of the actual mirror on a high-quality substrate. Both the single and the multilayer mirrors have a high reflectivity for their relevant energy range, a low roughness on their surfaces and a good uniformity of these properties over the whole optical wavelength. The investigations described here are performed by means of X-ray reflectometry (XRR), transmission electron microscopy (TEM), optical profilometry (OP) and atomic force microscopy (AFM).Keywords：X-ray optics;multilayer mirror;total-reflection mirror;X-ray Reflectometry(XRR);magnetron sputtering;synchrotron radiation;free-electron lasers- 35
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Published：2020-08-12 -
Microscopy and spectromicroscopy with soft X-ray
Abstract：X-ray microscopy is capable of imaging particles in the colloidal size range directly in their aqueous environment with high spatial resolution. It is possible to combine this with high spectral resolution for spectromicroscopic studies. Two types of microscopes are common in X-ray microscopy, the transmission X-ray microscope and the scanning transmission X-ray microscope, whose setup is shown in this paper. While an X-ray microscope quickly takes high resolution images from an object, a scanning X-ray microscope as an analytical instrument is suited for spectromicroscopy. As an example for visualization of morphology, clay and soil samples have been imaged with a transmission X-ray microscope. Images from a cryotomography experiment based on X-ray microscopy images to obtain information about the 3D structure of microhabitats formed by bacteria and other soil colloids are shown. The analysis of a stack of images taken with a scanning transmission X-ray microscope to bring together morphology and chemistry within a soil sample is given.Keywords：X-ray microscopy;spectromicroscopy;XANES;NEXAFS;environmental sciences;colloids- 55
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Published：2020-08-12 -
Broadband aperiodic Mo/Si multilayer polarization elements for EUV region
Abstract：Broadband Mo/Si multilayer polarization optical elements were developed for the extreme ultraviolet (EUV) region, including a reflective analyzer and a transmission phase retarder. These multilayers were designed by a combined analytical/numerical method based on an aperiodic stack. Then these aperiodic multilayers were fabricated using direct-current magnetron sputtering technology. The multilayer structures were measured by an X-ray Diffractometer (XRD) working at the Cu-Kα line, and the polarization response was characterized by the polarimeter on the UE56/1-PGM1 beamline at BESSY-II, in Berlin. The measured s-polarized reflectivity is higher than 15% over the 13~19 nm wavelength range,and nearly constant s-reflectivity, up to 37%, is observed over the 15~17 nm wavelength range. Furthermore, these aperiodic multilayers show high s-reflectivity and polarization over a wide angular range at fixed wavelength. The measured phase shift is 41.7° over the 13.8~15.5 nm wavelength range. Using an aperiodic transmission phase retarder and a reflection analyzer, a complete broadband polarization analysis system was developed. The polarization properties of the synchrotron radiation from the beamline UE56/1 PGM1 at BESSY-II were systematically characterized in the 12.7~15.5 nm wavelength range by this newly developed broadband polarization analysis system. This kind of broadband multilayer polarizing elements can be used in EUV polarization measurements and will greatly simplify experimental arrangements.Keywords：polarization element;Multilayer;phase retarder;polarimeter;extreme ultraviolet;synchrotron radiation- 47
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Published：2020-08-12 -
X-ray imaging Fresnel zone plates and fabrication
Abstract：In order to investigate the principle and fabrication technique of Fresnel zone plates (FZPs), a diffractive optical element used in X-ray imaging with the best resolution currently is presented. A theoretical analysis of the spatial resolution depending on the outermost zone width is given. An analytical expression of the diffraction efficiency in terms of thickness and X-ray refractive index of the zone plate is also provided. Electron beam lithography combined with X-ray lithography is employed to fabricate FZPs. Experimental results indicate that the outermost zone width is 150 nm and the aspect ratio is 4, which satisfies the X-ray imaging system requirements of high resolution, high aspect ratio as well as high precision.Keywords：Fresnel zone plate;X-ray imaging;spatial resolution;diffraction efficiency- 57
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Beam line design for high-resolution diffraction at synchrotron radiation sources
Abstract：The general design of a high-resolution diffraction beamline at a third generation X-ray synchrotron radiation source is presented. For this, we introduce the basics of high resolution diffraction and the optical elements necessary to prepare a nearly parallel but intense X-ray beam with well-defined photon energy for high-resolution application. In particular, the function of double-crystal and four-bounced crystal monochromators is explained in terms of X-ray dynamical theory. As an example, we present the layout of the High Resolution Diffraction (HighRes) beamline at the new synchrotron radiation source PETRA III in Hamburg (Germany) which will become operational in 2009. By optimizing the optical components, a resolution in q-space will be achieved down to Δq=10-5 nm-1 with micron beam size and a flux of more than 1011 cts/s.Keywords：synchrotron radiation source;diffraction beamline;high resolution- 48
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Suppression of higher-order harmonics by different material filters in 13~43 nm
Abstract：The Spherical Grating Monochromator(SGM) branch of Spectral Radiation Standard and Metrology (U27) beamline is specially built for measurement of the properties of optical elements and detectors. In order to accurately measure the performance of optical elements, higher-order harmonics must be suppressed efficiently. For the existing beamline where the design cannot readily be altered, the simplest method is to use transmission filters to suppress higher-order harmonics.With a 840 l/mm transmission grating used behind the exit of SGM in U27 beamline, the exit beam can be dispersed and the contributions of the different orders can be analyzed. Results of higher-order suppression by 200 nm, 400 nm, 600 nm thickness Al filters, 100/50/200 nm, 100/50/150/150/250 nm thickness Si3N4/Mo/Si, Si3N4/Mo/Si/Mo/Si multilayers and Al/Mg/Al filter in the region of 13~43 nm show that when the thickness of Al filter is 400 nm, and the wavelength is between 17 nm and 33 nm , the contributions of higher orders to the detector signal intensity are less than 2% , and the detector intensity is strong enough when the beam on. After being corrected by quantum efficiency of the detector, higher order contributions are less than 0.6%. Si3N4/Mo/Si/Mo/Si filter can be efficiently used to suppress higher-order harmonics in the region of 13~19 nm , and Al/Mg/Al filter can be used to suppress higher-order harmonics in the region of 30~43 nm efficiently. These are important for the accurate calibration of absolute reflectivities of multilayer and detector etc.Keywords：synchrotron radiation;higher-order harmonic suppression;filter- 18
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Research of oxygen activation by synchrotron radiation in optical component cleaning process
Abstract：In order to optimize the optical component cleaning process, the oxygen dissociation by synchrotron radiation has been researched by analyzing the gas composition produced in cleaning process. The gas composition is measured by quadrupole mass spectra when synchrotron radiation light irradiates the oxygen filled in vacuum chamber. The gas composition and content can be established by analyzing the data gathered. Experimental results indicate that oxygen can be dissociated by synchrotron radiation light to produce some species with strong oxygenation, such as oxygen atom and ozone. The content of oxygen atom is about 1% and the content of ozone is about 0.005%~0.01% in cleaning process.Keywords：synchrotron radiation;activated oxygen;oxygen atom;ozone- 29
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Published：2020-08-12 -
Correction of pattern transfer errors for SU-8 UV deep lithography
Abstract：The diffraction and absorption of UV light in SU-8 resist makes it very difficult to fabricate high precision microstructures with high aspect ratio in the process of UV LIGA, because the absorption coefficient gets bigger and the penetration depth gets shorter rapidly as the wavelength gets shorter. Therefore, such factors having effect on the precision of deep UV lithography as diffraction effect, exposure dosage, wavelength and distribution of fly's eyes lens etc., are investigated in this paper. A method of correcting pattern transfer errors is developed through investigation of pattern transfer errors. Proposed method adopts the feature classification and area evaluation to modify the mask contour, thereby making the lithography contour as close as possible to the desired contour. In addition, it can be used to reduce the complexity and enhance the correction efficiency.Keywords：SU-8 photoresist;UV deep lithography;mask;pattern transfer;error correction- 60
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Mono- and polycapillary optics-State of the art and applications
Abstract：For more than 20 years, capillary optics have been used in X-ray analytics. During this time the technology of manufacturing capillary optics passed a considerable development. Whereas in the beginning of 1990s assembled capillary optics were tested in research laboratories, at present monolithic polycapillary optics are widely used in commercial X-ray analytical instruments. These optics show capillary sizes in the micrometer region and their physical behaviour can be described in terms of geometrical optics using ray tracing programs. Recently capillary channel sizes of 200 nm and below were realised due to further improvement of the manufacturing technology for polycapillary structures. At such small structures, the appearance of wave effects for X-ray radiation was observed. Finally, application examples for capillary optics in micro X-ray fluorescence analysis and micro X-ray diffractometry are presented.Keywords：X-ray capillary optics;wave properties;nanocapillary;X-ray analytics- 40
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Published：2020-08-12 -
Optimum choice of combination wavelengths in near infrared analysis for soil organic matter
Abstract：By taking the 85 black soil samples in north of Jilin province as the examples of analyzing organic matter,a optimum choosing method of combination wavelengths for calibration was presented by the ways of Multiplicative Scatter Correction (MSC) and correlation spectrum, and the model was optimized progressively based on experience and reference wavelength theory. Finally, the model shows the correlation coefficient of 0.90, Root Mean Square Error of Calibration(RMSEC) of 0.36%, and Root Mean Square Error of Calibration Value(RMSECV) of 0.40%,which approaches to the calibration of continuous spectrum by Partial Least Square(PLS). Rusults indicate that the model is simple and stable, and can offer a reference for general black soil condition investigation in north of Jilin province.Keywords：soil nutrition;near infrared spectroscopy;precision agriculture;multiplicative scatter correction;correlation spectrum- 47
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Choice of wave band in design of minitype near-infrared corn protein content analyzer
Abstract：The calibration models for protein concentration in corn samples were established by Fourier transform near-infrared diffuse reflection spectroscopy and Partial Least Square (PLS) regression. According to the prediction effect the best wave band was chosen to provide a basis for designing a minitype near-infrared corn protein content analyzer. The spectra were processed by Multiplicative Scatter Correction(MSC) method firstly, then the original spectra, the first derivative spectra and the second derivative spectra were processed by Savitzky-Golay smoothing method. The following 5 wave bands, the whole region, combination region, the first overtone region, the second overtone region and the protein functional group bands were selected for establishing 15 calibration models adopting the original spectra, the first derivative spectra and the second derivative spectra respectively in each band. By adjusting the number of Savitzky-Golay smoothing points and number of PLS factors simultaneously and comparing with PLS computational experiments several times, the optimal number of smoothing points and number of factors for each models were obtained based on the prediction effect, and then the best one was selected. The research results show that the prediction effect using the first derivative spectra in the first overtone region is best one, and the correlation coefficient, the Root Mean Square Error of Prediction(RMSER) and the Relative Root Mean Square Error of Prediction(RRMSEP) for the corresponding model are 0.945, 0.357, and 3.340%, respectively. It shows that the first overtone band (7 000~5 500 cm－1) can replace the whole band, and get better calibration effect.Keywords：corn;protein;near infrared spectroscopic analysis;partial least square regression;wave band choice- 55
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Multi-channel nano-second framing camera with gate selection
Abstract：The ultra high-speed photography is an essential diagnostic tool in research on ultra fast process. The image diagnostic instrument is required to obtain high speed framing images in high framing rate, short exposure time and suitable gap,and recording ultra fast process in fix time. A nanosecond framing camera was developed using optical framing technique and gate selection methord in this paper. An image was split into eight using octagonal pyramid mirror in the space and each split image has equal optical energy and original information. A nearly-pasted image intensifier with gate selection was also developed to enhance the weak optical image. Each channel uses an independent image intensifier with gate selection and an CCD camera. This system could capture eight images in sequence at the shortest exposure time and gap of 3 ns and 10 ns, and the exposure time and gap could be adjusted separately.Experimental results show that the framing speed achieves 1×108 frame/s and dynamic spatial resolution of 15 lp/mm. Several experiments, such as beam diagnose of electron pulse, plasma luminescence process have adopted this camera and many useful results are obtained.Keywords：nano-second framing camera;8-channel framing;nearly-pasted image intensifier with gate selection;octagonal pyramid splitting- 53
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Published：2020-08-12 -
Load balancing and task scheduling of heterogeneous multiprocessor system
Abstract：In order to share various resources proportionally and to optimize the utility of system resource in a heterogeneous multiprocessor, a Load Balance Heuristic Optimization Algorithm(LBHOA) is proposed after the analysis of load balance and learning of task scheduling model. LBHOA uses heuristic search technique to choose the node of least estimation value and to spread search until finding a target note that has a least value of time spending in all complete distributive notes. The experimental results indicate that LBHOA can reduce 10% of average response delay and 15% of working time comparing with WLCA and LTGA and also can reduce computing complexity in resource allocating, which meets the requirements of load balance and optimization scheduling in heterogeneous multiprocessor system.Keywords：heterogeneous cluster;load balancing;task scheduling;Load Balancing Heuristic Optimization Algorithm(LBHOA)- 37
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Published：2020-08-12 -
Research and implementation of digital control of dynamically tuned gyroscope rebalance loop
Abstract：To overcome the problems caused by the controller compensation and temperature compensation in the analog rebalance loop, the method and implementation of the digital control were researched.A highly precision, adjustable three-phase inverter power source of Dynamically Tuned Gyroscope(DTG) motor was designed using SVPWM method based on DSP to solve the problems on adjusting the frequency, low stability of phase and low efficiency of motor power source. The two-input-two-output frequency characteristic analyzer was designed using dSPACE Hardware-in-loop(HIL) system, the open loop discrete transfer function matrix of digital rebalance loop was identified. Based on matrix inverse and traditional controller method the decoupling and compensation controller was designed to get better dynamic performance of DTG. The experiment shows that the frequency stability of designed DTG motor power source is better than ±1.5×10－6, waveform distortion is lower than 5%, which meets the demand of DTG. The band width of lock loop under control is higher than 70 Hz, overshoot is lower than 5%, rising time is shorter than 5 ms, and the cross coupling is lower than 1% between the two axis when there is a 10 Hz sinusoidal input, which has better dynamic performance than the analog rebalance loop in guaranteeing the stability margin, establishing the basis of modern control method application in DTG rebalance loop.Keywords：digital design;dynamically tuned gyroscope;rebalance loop;transfer function identification- 29
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Published：2020-08-12
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