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The reflective phase shift of multilayer mirror is one important property required in EUV lithography and attosecond pulses experiments. The reflective phase shift of the periodic Mo/Si multilayer mirror was characterized by combining the reflectivity with total electron yield signal at the synchrotron radiation in Hefei. The multilayer was fabricated using direct current magnetic sputtering method. Using the wavelet transform approach, the period and each layer thickness were obtained, the small angle X-ray reflective data from X-ray diffractometer were fitted using these data as the mutilayer's initial structure. The TEY signal of the multilayer is coincided with the surface electron field of the multilayer. A thick Si layer was used to eliminate the effect of the multilayer's surface layer on the TEY signal. The retrieved difference in reflected phase from the incident phase was obtained combining the reflectivity with the total electron yield signal and it is similar with the calculated phase shift of the multilayer.

The design procedures were discussed in detail for a normal incident chirped Mo/Si multilayer mirror with Group Delay Dispersion (GDD) of −3600 as 2 in the wavelength region of 13–17 nm. The GDD was calculated using an analytical approach by fitting the optical constants of the coating materials in the wavelength range of 12.8–17.2 nm, respectively. The final structure of the chirped mirror was obtained by using the simplex algorithm from the initial structure obtained by the genetic algorithm based on structure generated by a random generator. After considering the interfacial roughness and layers thickness deviation, the effects on the reflectivity and the GDD were discussed. It was found that the average reflectivity decreases from 5.98% to 4.22% and the average GDD decreases from −3561.86 as 2 to −3462.03 as 2 , the vibration of GDD were larger than that of the reflectivity. The reflectivity was affected greatly by the 9 th layer and the GDD was affected greatly by the 25 th layer when each layer thickness changes ±0.2 nm. Compared with the GDD, the reflectivity was affected greatly by the layer thickness error.

Aperiodic molybdenum/silicon (Mo/Si) multilayer designed as a broadband polarizer with reflectivity over a wide wavelength range of 13–30 nm at a fixed incidence angle of 45° was developed by a numerical method. The multilayer was prepared using direct current magnetron sputtering. The reflectivity and polarizing properties were characterized using synchrotron radiation. In 13–30 nm wavelength region, the measured s -reflectivity ( R s ) with standard deviation is 13.5%±3.1%, p -reflectivity ( R p ) with standard deviation is 1.4%±0.5%. The mean of polarization degree is 81.2%. This broadband multilayer polarizer can be used in extreme ultraviolet polarization measurements, and will greatly simplify experimental arrangements.

Design, fabrication and characterization of aperiodic tungsten/carbon (W/C) multi-layer mirror were studied. W/C multi-layer was designed as a broad-angle reflective supermirror for Cu–Kα line (λ = 0.154 nm) in the grazing incident angular range (0.9–1.1°) using simulated annealing algorithm. To deposit the W/C depth-graded multi-layer mirror accurately, we introduce an effective layer growth rate as a function of layer thickness. This method greatly improves the reflectivity curve compared to the conventional multi-layer mirror prepared with constant growth rate. The deposited multi-layer mirror exhibits an average reflectivity of 19% over the grazing incident angle range of 0.88–1.08° which mainly coincides with the designed value. Furthermore, the physical mechanisms were discussed and the re-sputtering process of light-atom layers is accounted for the modification of layer thicknesses which leads to the effective growth rates. Using this calibration method, the aperiodic multi-layer mirrors can be better fabricated for X-ray optics.

Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B4C multilayer mirror was designed for Kirkpatrick–Baez (K–B) microscopy working at TiKα line (4.75 keV), which is highly reflective both at hard X-ray (CuKα line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K–B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

A recent development of mirrors is reviewed in this letter. For some applications, such as the hard X-ray telescope, polarization measurements in synchrotron radiation facilities, extreme ultraviolet (EUV) solar observations, and dense plasma diagnostics in China, a series of non-periodic novel multilayers with special performance are developed. X-ray supermirror, EUV broadband polarizer, EUV wide-angular mirror, and double period Kirkpatrick-Baez (K-B) mirror are successfully designed by using different multilayer stack structures. OCIS codes: 310.0310, 340.0340, 350.1260. doi: 10.3788/COL201008S1.0163.

Aperiodic molybdenum/silicon broadband multilayer analyzers with constant reflectivity over a wide spectral range for a fixed incidence angle have been designed using a combined analytical/numerical method. The analyzers were fabricated using direct current magnetron sputtering and characterized using the soft X-ray polarimeter at the BESSY facility. Nearly constant s-reflectivity, up to 37%, is observed over the 15–17 nm wavelength range at a grazing incidence angle of 50°, and the degree of polarization is over 98%. Furthermore, the analyzer also exhibits high s-reflectivity and polarization over a broad angular range, 43–53°, at a fixed wavelength of 15.5 nm. This kind of broadband multilayer analyzer can be used in extreme ultraviolet polarization measurements, and will greatly simplify experimental arrangements.

An adaptive local search-based simulated annealing (ALSA) algorithm is proposed for the design of the wide band-pass multilayer optical elements operating in the hard and soft X-ray wavelength ranges. At present the SA algorithm has been kept as simple as possible and its performance is being studied before a series of modifications are made to tailor the SA algorithm to optimize super-mirror for particular applications. The algorithm has also been developed with two specific areas in mind: a W/C broad angle super-mirror for hard X-ray applications and a Mo/Si wide band super-mirror operating at normal incidence in the EUV spectral region. The design results show that the ALSA algorithm method has the flexibility to design a wide range of multilayer structures and in comparison to other techniques has good results although computationally more intensive.

A weakly modulated dielectric grating is equivalent to a planar waveguide. As the high-order spatial sub-waves couple with the leaky mode of the grating, guided-mode resonance (GMR) occurs. In this paper, the resonance positions of a weakly modulated dielectric grating are studied based on the eigenvalue equation of a planar waveguide, and the results agree with the rigorous coupled-wave analysis (RCWA) very well. This shows that double reflection peaks at normal incidence can be realized and the reasons are given in detail. The reason that GMR is sensitive to the incident angle and the grating period is also discussed. GMR filters with good filtering features can be realized by using the thin film effect.

The soft X-ray interferometry is completed by the Mach-Zehnder interferometer using a soft X-ray laser, and it is also an important method to measure the electron densities of a laser-produced plasma near the critical surface. It is apparently demonstrated in this paper that the incident angle of each optical element in the soft X-ray Mach-Zehnder interferometer should be near normal incidence based on the polarized characteristics of the soft X-ray multilayers, and the product of reflectivity and transmission of the beam splitter should be taken as a standard of design according to the structure of the soft X-ray Mach-Zehnder interferometer. The beam splitters used in the soft X-ray interferometry at 13.9 nm are fabricated using the ion beam sputtering. The figure error of the beam splitter has reached the nanometer magnitude, in which the product of reflectivity and transmission of the beam splitter is more than 1.6%.

To develop high quality dispersion optics in the X-ray region, the sliced multilayer transmission grating is examined. Dynamical diffraction theory is used to calculate the diffraction property of this volume grating. A WSi2/Si multilayer with a d-spacing of 14.3 nm and bi-layer number of 300 is deposited on a superpolished silicon substrate by direct current magnetron sputtering technology. To make the transmission grating, the multilayer is sliced and thinned in the cross-section direction to a depth of 23-25 μm. The diffraction efficiency of the grating is measured at E = 8.05 keV, and the 1st-order efficiency is 19%. The sliced multilayer grating with large aspect ratio and nanometer period can be used for high efficiency and high dispersion optics in the X-ray region.

ZrO2 thin films were deposited by a wet chemical sol–gel method from forced hydrolysis of aqueous ZrOCl2 solution. Transmission electron microscopic observations confirmed the existence of little nanosized monoclinic ZrO2 particles in clear stable ethanolic ZrO2 colloidal suspensions. Twenty layers of ZrO2/SiO2 high reflectance filters using a quarterwave stack were fabricated by sol–gel spin-coating on K9 glass substrate. This filter exhibits a wide reflectance band near 1064 nm and a high transmittance region.

In this paper, colloid-based highly reflective coatings consisting of alternating layers of quarterwave thick high- and low-refractive index components were deposited on glass substrates by a sol–gel spin-coating method. SiO 2 was used as the low-refractive index component, and ZrO 2 as the high-refractive index material. The colloidal suspension of ZrO 2 , prepared by hydrothermal hydrolysis of ZrOCl 2 , contained monoclinic nanocrystalline ZrO 2 , with an average particle size of 15 nm. A minimum transmittance of 1% near 1064 nm was obtained from a 20-layer SiO 2 –ZrO 2 /PVP multilayer film. The ZrO 2 particles were deposited in an ethanolic suspension containing polyvinylpyroldione (PVP) as a binder. The maximum transmittance in the visible range was about 85%. A 1-on-1 laser-induced damage threshold of 16 J/cm 2 for the 20-layer SiO 2 –ZrO 2 /PVP film was observed using a Q-switched Nd:YAG high power laser at a wavelength of 1.06 μm and with a pulse width of 2.5 ns.

Influence of interface roughness on the reflectivity of Tungsten/boron-carbide (W/B4C) multilayers varying with bi-layer number, N, is investigated. For W/B4C multilayers with the same design period thickness of 2.5 nm, a real-structure model is used to calculate the variation of reflectivities with N=50, 100, 150, and 200, respectively. Then, these multilayers are fabricated by a direct current (DC) magnetron sputtering system. Their reflectivity and scattering intensity are measured by an X-ray diffractometer (XRD) working at Cu K\alpha line. The X-ray reflectivity measurement indicates that the reflectivity is a function of its bi-layer number. The X-ray scattering measured results show that the interface roughness of W/B4C multilayers increases slightly from layer to layer during multilayer growing. The variation of the reflectivity and interface roughness with bi-layer number is accurately explained by the presented real-structure model.

A preparation process of a surface perturbation target was introduced in this article. Through laser interference and a nickel-electroplate process, sinusoidal surface perturbation on the photoresist and nickel plate mold with sinusoidal surface perturbation were obtained. We transferred sinusoidal perturbation on brominated polystyrene foils by a spin-coating process. By removing the brominated polystyrene foils from the nickel-plate mold, the brominated polystyrene sinusoidal surface perturbation target was obtained. The transfer precision of the sinusoidal perturbation was measured by scanning electron microscopy. The measurements showed that the surface perturbation was transferred precisely. The surface roughness on the surface perturbation target was about 15.0 nm, analyzed by an α-step apparatus.

Band structures of one-dimensional (1D) photonic crystals (PCs) containing dispersive left-handed metamaterials are studied theoretically. The results show that the structure possesses a type of photonic band gap originating from total internal reflection (TIR). In contrast to photonic band gaps corresponding to zero average refractive index and zero phase, the TIR gap exhibits sharp angular effect and has no polarization effect. It should also be noted that band structures of transverse electric (TE) and transverse magnetic (TM) mode waves are exactly the same in the PCs we studied.

The X-ray low angle reflectivity measurement is used to investigate single and bilayer films to determine the parameters of nanometer-scale structures, three effectual methods are presented by using X-ray reflectivity analysis to provide an accurate estimation of the nanometer film structures. The parameters of tungsten (W) single layer, such as the material density, interface roughness and deposition rate, were obtained easily and speedily. The base metal layer was introduced to measure the profiles of single low Z material film. A 0.3 nm chromium (Cr) film was also studied by low angle reflectivity analysis.

Transmission characteristics are studied for hybrid structures combining defects and multiple heterostructures. It is shown that the nontransmission frequency range can be substantially enlarged and the phenomenon of multiple-channeled filtering can be realized by adjusting the number, position, and size of the defects. One, two, and three channeled filters are considered in the structures. Examples are studied theoretically by transfer matrix methods.

Intrinsic stresses of carbon films deposited by direct current (DC) magnetron sputtering were investigated. The bombardments of energetic particles during the growth of films were considered to be the main reason for compressive intrinsic stresses. The values of intrinsic stresses were determined by measuring the radius of curvature of substrates before and after film deposition. By varying argon pressure and target-substrate distance, energies of neutral carbon atoms impinging on the growing films were optimized to control the intrinsic stresses level. The stress evolution in carbon films as a function of film thickness was investigated and a void-related stress relief mechanism was proposed to interpret this evolution.

For extreme ultraviolet (EUV) radiation and soft X-rays, real part of the refractive indices of all materials are very close to unity, coupled with high absorption, makes the realization of high-reflective mirrors (just like visible and infrared light) impossible. Multilayer is a nano-structure, alternating of low- and high-Z materials in a periodic way, which can greatly enhance the reflectivity via the interference of light reflected from interfaces, like crystal optics. Reflective mirrors, polarization elements, monochromators, etc, can be made basing on multi-layer structures. Zone plate is a powerful tool to focus the light beam for EUV and soft X-ray into nanometer scale, which is produced by electron beam etching method. However, for hard X-ray, the zone plate will has smaller width of outmost layer and larger aspect ratio, which is difficult to realize. Multilayer Laue lens (MLL) is a promising method to overcome these limitations. MLL is a novel linear zone plate which is produced by depositing the depth-graded multilayer, according to the zone plate law reversely, on flat substrate and then slicing and polishing it to an ideal aspect ratio. In this paper, some recent development of multilayer optics for EUV and X-ray regions in IPOE will be introduced.

Chirped Mo/Si multilayer mirrors used in 13-17nm region have been designed using analytical approach based on the combination of genetic algorithm and simplex algorithm. The Cauchy equation and the polynomial expression were used to fit the real part and the imaginary part of the optical constants of Mo and Si in the wavelength region of 12.8-17.2nm, respectively. The reflectivity, reflective phase, group delay a nd group delay dispersion of the multilayer were calculated based on the Fresnel iterative equations. The initial structure of the multilayer was obtained by using the genetic algorithm, and the final structure of the mirror was optimized by using the simplex algorithm. We got the different multilayer mirrors for the target GDD of -2800 as 2 , -3600 as 2 , and -6500 as. For these three multilayer mirrors, the average reflectivities in the wavelength range of 13-17 nm are 7.00s 0.08 %, 5.99s 0.05 %, and 6.00s 0.05 %, respectively. And the average GDD in the same wavelength range are -2793.22 s 104.00 as

To improve the stress property of multilayer optics working in extreme ultraviolet and x-ray range, mono-layer thin films of Mo, MoSi2, Si, with thickness of 100nm, and periodic multilayers of [Mo/Si] 20 , [MoSi 2 /Si] 20 , with period thickness of 20nm, were prepared by direct current magnetron sputtering method. Before and after each deposition, the radius of surface curvatures of substrates were measured using a stylus profiler and then the film stress was calculated. The measurement results indicate that, Mo, MoSi 2 and Si mono-layer thin films all shows compressive stress, while Mo/Si multilayer shows tensile stress, i.e., the film stress changes significantly during Mo/Si multilayer growth. For MoSi 2 /Si multilayer, the film stress still keeps compressive, which indicates more stable stress property.

Recently, the scope of the investigation of the deformation mechanism extended to the micrometer and submicrometer regimes. The sphere−substrate contact method was usually used because it is rather difficult to make two micrometer or submicrometer spheres contact each other precisely. Here, we used the sphere−sphere contact method via a novel, simple process to investigate the deformation of spheres. The silica particle size ranges from 400 to 900 nm. Traditionally, the harder the particle, the smaller both the contact radius and the adhesion force. Therefore, it is widely accepted that silica particles should undergo elastic deformation, but we found that silica particles underwent plastic deformation rather than elastic deformation because of van der Waals interaction. The contact radii were observed by scanning electron microscopy (SEM).

X-ray grazing incidence supermirror which has extremely broad reflection band is a kind of multilayer with different each layer thickness down through the structure. The x-rays with different wavelengths or at different grazing incident angles can be reflected at different position in the supermirror structure and its band or angular response thus can be extended. These supermirrors have been developed and applied widely in many fields, especially in astrophysics. Existing approaches for designing similar neutron supermirrors are shown to provide respectable performance when applied to x-ray multilayers. However, none of these approaches consider the effects of imperfect layer interfaces and absorption in the overlying layers and all of them insist on the structure with the ratio of the layer thickness of absorbing material to the bi-layer spacing being a constant of 0.5. Adaptations of neutron designs that take these effects into account are presented in the present paper. In addition, other approaches, such as the method based on the combination of analytical and number methods, also are included and discussed in this paper. Two kinds of supermirrors with broad photon energy band or broad angular response have been designed using these different design methods. The results show that for specific applications, different optimization methods with different initial structures should be chosen accordingly to expect some overall improvement on performance of x-ray supermirrors.

a1 Institute of Precision Optical Engineering, Department of Physics, Tongji University, Shanghai 200092 eChina 2 Research Center of Laser Fusion, CAEP, P.O. Box 919-988, Mianyang 621900, China a Abstract: An auxiliary visible imaging method was introduced to solve the axial and pointing alignment of x-ray Kirkpatrick-Baez optics. Through ZEMAX simulation and x-ray imaging experiments, the axial and pointing alignment accuracy were determined to be ±300 m and ±20 m respectively. The numerical aperture of x-ray Kirkpatrick-Baez optics is rather small, so it’s impossible to adjust Kirkpatrick-Baez system by visible imaging directly. An auxiliary visible lens was designed, which was equivalent to x-ray Kirkpatrick-Baez optics on conjugate relationship and accuracy control. The comparative experiments of visible imaging and x-ray imaging indicate that this auxili ary system could meet the alignmen t accuracy of Kirkpatrick-Baez optics. Keywords: auxiliary visible imaging, x-ray Kirkpatrick-Baez optics, axial alignment, pointing alignment

A double-periodic multilayer method was proposed to test KBA system of 4.75keV using 8keV source. Alignment of angle is the key for most of grazing incidence systems in x-ray range. But for soft x-ray, strong absorption makes the alignment have to be operated in vacuum, which is difficult enough. A double-periodic multilayer was used to experiment at 8keV in air replacing 4.75keV in vacuum. This multilayer includes two parts, the top and the bottom. The top is W/B 4 C multilayer with four bilayers and 6.93nm periods. The bottom is W/B 4 C multilayer with 10 bilayers and 3.95nm periods. For 8keV energy, x-ray will penetrate through the top and reflected by the bottom. While for 4.75keV, x-ray will be reflected by the top directly. The full width of half maximum is 0.1° at 8keV and 0.3° at 4.75keV, so it is accurate enough for 4.75keV to experiment at 8keV, which was also verified by the 1-D KBA experiment. This double-periodic multilayer provides a valid solution for alignment in soft x-ray range.

Compound refractive x-ray lens is a unique device to form image of opaque object which is illuminated by x-rays. It is consisted of a lot number of placed in-line concave microlenses and works like ordinary refractive lens for visual light. In contrast to other x-ray optical devices, it could achieve satisfying resolution without complicated equipment. The spherical compound refractive x-ray lens used in this experiment is composed of 123 biconcave microlenses of 200 μm diameter. Each microlens was formed by the epoxy between two bubbles which were injected into an epoxy-filled glass capillary. There are three advantages ensuring good image quality of the lens for using in hard x-rays: (1) The epoxy (C100H200O20N, 1.08 g/cc) is composed of carbon, hydrogen and nitrogen, each of them is characterized by a low absorption coefficient for 5-30 keV x-rays. (2) Because of the nature of physics forming the bubble, the lens surface quality is extremely good. (3) The capillary makes sure that the series of unit lenses are well aligned coaxially. The lens focal length is 114 mm at 8.05 keV which is adjusted according to thick-lens analysis. X-ray images of grid mesh are compared between using a copper anode x-ray tube without filter and a synchrotron radiation source with monochromator. It could be found that the resolution and contrast are improved a lot by using monochromatic x-rays. The field of view and geometrical distortion around the edges of the field of view are reduced because of using a synchrotron radiation source. For x-ray tube as source the lens achieved a spatial resolution of 5 μm and field of view of about 700 μm. For a synchrotron radiation source, that is 3.8 μm by 2.3 μm resolution and field of view of about 316 μm by 128 μm.

Hard X-ray imaging by a spherical compound refractive lens is presented. The lens is composed of 123 biconcave microlenses with a size of 200 μm in diameter. Each microlens was formed by the epoxy between two bubbles, which were injected into an epoxy-filled glass capillary. The focal length of the lens is 114 mm at 8.05 keV. The light source was obtained by using a copper anode X-ray tube without a filter. The lens can be achieved a spatial resolution of 5 μm with field of view of about 700 μm, and 1–3 μm resolution may be obtainable by using monochromator and diaphragm.

Multilayer coatings are key optical components in the EUV, soft X-ray and X-ray range. At Institute of Precision Optical Engineering (IPOE), the development of multilayer optics has been impelled for their wide applications in X-ray laser, plasma diagnostics, astronomical observation and synchrotron radiation. The paper presents our recent results of periodic multilayers of Mo/Si, Cr/C, Cr/Sc, La/B4C, Mo/B4C, Si/C, Si/SiC, Mg/SiC Mo/Y and Ru/Y. To improve the reflectivity of Ru/Y multilayer mirrors, Mo layers were inserted between Ru and Y layer. The Mo barrier layers suppress intermixing between Ru and Y, thereby increasing the reflectivity of Ru/Y multilayer. We also discuss the application of Mo/Si, Mo/Y, Mo/B4C, La/B4C non-periodic multilayers in EUV broadband polarization measurement.

Three kinds of multilayer mirrors were developed for solar observation and earth’s magnetosphere observation at Extreme Ultraviolet (EUV) wavelength region. The first one is Mo/Si multilayer mirror, designed for solar Fe-XII emission line at wavelength of 19.5nm. The reflectivities are in the range of 38.7~42.9%, measured at National Synchrotron Radiation Laboratory (NSRL), Hefei, China. Th e second high-reflective multilayer is designed for solar He-II radiation at 30.4 nm. At this wavelength, SiC/Mg multilayers were investigated, and as high as 50.0% measured reflectivity was obtained at incident angle of 10u. Aperiodic SiC/Mg multilayers were also designed for wide angular ranges of 15-22u and 12-21u. The third multilayer mirror was a dual-function mirror used for earth’s magnetosphere observation, which requires high-reflective for He-II emission line at wavelength of 30.4nm but low-reflectance at 58.4nm from ionosphere He-I emission. Using aperiodic SiC/Mg multilayer stack, the dual-function multilayer mirror was designed by genetic algorithm. Compared to periodic multilayer, the dual-function multilayer suppresses the reflectivity for He-I at 58.4nm from 2.2% to 0.1%, without loss of the reflection for He-II at 30.4nm, significantly. These multilayer mirrors were all prepared by magnetron sputte ring system in IPOE, and measured at NSRL, China. Keywords: EUV astronomical observation; multilayer; magnetron sputtering; synchrotron radiation

SiC/Mg and B(4)C/Mo/Si multilayers were designed for He-II radiation at 30.4 nm. These multilayers were prepared by use of a direct current magnetron sputtering system and measured at the National Synchrotron Radiation Laboratory, China. The measured reflectivities were 38.0% for the SiC/Mg multilayer at an incident angle of 12 deg and 32.5% for the B(4)C/Mo/Si multilayer at 5 deg, respectively. A dual-function multilayer mirror was also designed by use of the aperiodic SiC/Mg multilayer. Annealing experiments were performed to investigate the thermal stability of the SiC/Mg multilayer. The interface of the SiC/Mg multilayer before and after annealing was studied by electron-induced x-ray emission spectra, which evidences the absence of thermal reaction products at the interfaces after annealing.

Multilayer mirrors are the important optical elements for astronomical observation at extreme ultraviolet region. In this article, three kinds of multilayer mirrors were introduced for solar observation and magnetosphere observation. Mo/Si multilayer mirror was fabricated for solar Fe-XII emission line at wavelength of 19.5nm. For solar He-II radiation at 30.4 nm, Mo/Si, Si/SiC, Si/C, Si/B4C and Mg/SiC multilayers were investigated, and the measurements results shows that Mg/SiC multilayer provides the highest reflectivity of 43.8% at incidence angle of 5 degree. The third multilayer mirror was a dual-function mirror used for earth's magnetosphere observation, which requires high-reflective for He-II emission line at wavelength of 30.4nm but anti-reflectance at 58.4nm from ionosphere He-I emission. Using aperiodic Mg/SiC multilayer, the dual-function multilayer mirror was designed. Compared to periodic multilayer, the dual-function multilayer suppresses the reflectivity for He-I at 58.4nm from 2.2% to 0.1%, without loss of the reflection for He-II at 30.4nm, significantly.

The SiC/Mg and B4C/Mo/Si multilayers were fabricated for He-II radiation at 30.4nm. The measured reflectivitier were 38.0% for SiC/Mg multilayer at incident angle 12 degree, and 32.5% for B4C/Mo/Si multilayer at 5 degree, respectively.

Multiple heterostructures inserted with defects are presented. Single and double layer guided-mode resonance (GMR) Brewster filters with multiple channels are introduced. Single and double chamber integrated optical filter arrays are fabricated.

The present status of studies on EUV, soft x-ray and x-ray multilayer in the Institute of Precision Optical Engineering (IPOE) is briefly reviewed. With the aim of realizing a Mach-Zender interferometer working at 13.9nm, we have developed a semitransparent beam splitter with multilayer deposited on the back side of a silicon nitride membrane. On the basis of the experimental optical properties of the beam splitter, design has been performed to define the multilayer structure that provides the highest product of reflectivity and transmission. Optimized Mo/Si multilayer has been successfully deposited on the back side of a silicon nitride membrane by use of the magnetron sputtering. Measurements by means of a reflectometer in Beijing Synchrotron Radiation Facility at 13.9nm and at an angle of 7.2° provide a reflectivity of 20% and a transmission of 22%. Such a beam splitter has been used for X-ray Mach-Zender interferometer at 13.9nm. The broadband multilayer analyzer in the range between 12.4nm and 20nm is designed, and made which can deviate the Quasi-Brewster's angle several degree and show very high polarization. The main feature of our design approach is the use of an analytical solution as a starting point for direct computer search, and the desired results can be given in a reasonable time. The method can be applied in different spectral range for suitable material combination. Supermirrors with broad angular band working at different wavelength such as Cu Kα line are designed, manufactured and measured. The results show that the performance of the supermirrors is in agreement with designed data.

The periodic mulitlayer with high reflectivity and small full width at half maximum (FWHM) in hard x-ray range, while the reflectivity of non-periodic multilayer decreases and FWHM increase. Therefore, the optimum coating design must be found out as a compromise between the requirements for the reflectivity and the FWHM. We have used purely numerical techniques to design broad angular multilayer mirror in angle intervals (2.9°-3.1°), which is starting from an appropriate periodic multilayer structure. In our method, the risk of local minimization of the merit function disappears, because we refined the desired depth-distribution of the period using a direct numerical algorithm and the analytical solution as a starting point for computer calculation. The plateau reflectivity can be obtained in a few minutes. The main feature of our approach is the use of an analytical solution as a starting point for direct computer search, and the desired results can be given in a reasonable time. This technique is able to design almost any given reflectivity spectrum both energy- and angle-dependent and in a reasonable amount of time. The periodic and non-periodic W/Si multilayer for grazing incidence multilayer mirrors at the K-edge of Ti (0.275 nm) were both designed and fabricated by high vacuum DC magnetron sputtering coater model JGP560C6, and the multilayer films were characterized by X-ray reflectivity measurements on a laboratory x-ray diffractometer(XRD) and the atomic force microscope (AFM). We find good agreement of the changing trend of surface roughness between the simulation of XRD and measurement of AFM.

We designed two kinds of supermirrors composed of Carbon and Tungsten in current paper. Using Simplex Optimization method, we designed C/W supermirror with broad incident angular range (0.5°~0.9°) at Cu Kα line (λ=0.154nm). Connecting the analytical method, based on oversimplified analytical and semi-empirical formulas, with the Simplex Optimization method, we designed C/W supermirror with broad photon energy range (16~25keV), at θ=0.5°. The negative effect, due to the interfacial roughness and diffusion between the adjacent sublayers in multilayer, also emerges in simulating the practice performance of the both supermirrors. The supermirrors with broad incident angular range were fabricated by DC magnetron sputtering, because such supermirror is easy to be measured at our lab, using X-ray diffractormeter. The measured reflectivity near the first order Bragg peak is about 30% at Cu Kα line. The roughness factor is about 0.84nm by the fitting data.

The broadband x-ray supermirrors have been designed, fabricated and studied experimentally. They are intended for operating in the photon energy range from 12.4 to 20keV at the fixed grazing incident angle of 0.5°. The choice of material pairs composing a non-periodic multilayer structure is considered from the maximum achievable reflectivity and the layer structure stability. Tungsten and silicon are selected, which have the great index contrast in this energy range and are suitable for fabrication with the use of the vested coating system. The interface width determined by transmission electron microscopy (TEM) lies in the range of 0.4~0.6nm. Following a theoretical approach including analytical and numerical techniques, the designed multilayer mirrors have a practically constant reflectivity of about 24% in the desired photon energy range. The multilayers were deposited onto polished silicon substrates by a high vacuum DC magnetron sputtering system and were characterized by x-ray diffractormeter (XRD) at 8.0keV. The experiments show that the sample has about 10% reflectivity in a wide angular range; The roughness of the interface for both tungsten on silicon layer and silicon on tungsten layer was estimated to be about 0.5nm. Oscillations in the reflectivity curve proved to be larger than the expected ones. They may be caused by the random variation of the layer thickness, as well as the interdiffusion between two materials. Possibilities for further improvements of wideband multilayer mirrors are analysed as well.

The status of polarizing optical elements for the soft x-ray range is reviewed. The criteria for optimum polarization of soft x-ray reflective analyzers, transmission polarizers and phase retarders based on multilayer interference structures are presented. Following these principles, soft x-ray polarizing optical elements have been designed. Designs of broad angular and wavelength range reflective analyzers based on a combination of analytical and numerical methods are also discussed.

K-B microscope intended for the use in inertial confinement fusion experiments was designed. The microscope operates at the 8keV x-ray energy and provides the 8X magnification. The parameters of the microscope are decided by requirements of ICF experiments. Ray tracing software (Zemax) is used to simulate optical system performance. Grazing angle range on the surface of mirrors and the assembly tolerance of centre grazing incident angle were both calculated. For the working energy is 8 keV, in order to obtain sufficient reflectivity at about 1° grazing angle on each mirror, multilayer should be coated on the mirrors. Two kinds of multilayer, periodic multilayer and non-periodic multilayer (supermirror), are discussed in the paper. Take into account the grazing angle ranges on the mirrors and the grazing angle tolerance, it is necessary to have a fairly constant reflectivity over a wide angular domain. Periodic multilayer has narrow bandpass, which cannot fulfill the requirement of such wide angular domain. The non-periodic structure multilayer was designed and fabricated. The results show this kind of non-periodic multilayer can be used in K-B microscope.

Theoretically, the spectral resolution of a multilayer can be improved through a combination of utilizing high reflectance orders and by decreasing the thickness of the scattering layer. We fabricate Mo/Si multilayers in the first, second, third, fourth and fifth reflectance orders with Mo layer thicknesses of 3.0 nm and 2.0 nm, respectively, using direct current magnetron sputtering. The structure of the multilayers is characterized with a grazing angle x-ray diffractometer (XRD). Then the reflectivity of the multilayers is measured in a synchrotron radiation facility. The results show that the spectral resolution increases with the increasing reflectance order and with the decreasing Mo layer thickness. The highest spectral resolution is improved to 117.5 in the 5th order for dMo = 2 nm, where the reflectivity is 18%.

We propose and demonstrate three approaches to achieve narrowband multichannel filters. These are multiple heterostructures with defects, guided-mode resonance (GMR) Brewster filters with multiple channels, and integrated narrow bandpass filter arrays. Transmission studies for multiple heterostructures with defects are presented. We show that the enlargement of the forbidden band and multiple-channel filtering can be reached simultaneously with these configurations. GMR Brewster filters with multiple channels can be obtained with a single-layer grating. The same properties can be obtained by use of double-layer structures that consist of a homogeneous layer and a grating with equal refractive index. We developed a combinatorial etching technique that has 32 elements on a single substrate with which to fabricate integrated narrow bandpass filters. Single- and double-chamber integrated optical filter arrays were fabricated by use of this etching technique. These narrowband multichannel filters and narrow bandpass filter arrays show good filtering features and can be utilized in many optical applications.

The polarization state of the BESSY UE56/1-PGM beamline radiation in the broad wavelength range of 12.7–15.5nm was measured using a molybdenum/silicon transmission phase retarder and a reflection analyzer with aperiodic multilayer interference structures, which can broaden the spectral response of these optical elements. The characteristics of the circular polarized undulator radiation, as well as the polarization properties of the two polarizing elements, were determined by a complete polarization analysis. Furthermore, the polarization of the radiation as a function of the undulator shift setting was also measured at the wavelength of 13.1nm by use of the broadband phase retarder-analyzer pair.

Experimental results on aperiodic broadband transmission molybdenum/silicon multilayer phase retarders for the extreme ultraviolet range are presented. The broadband phase retarders were designed using a numerical method and made using direct current magnetron sputtering on silicon nitride membrane. The polarization properties of these aperiodic transmission phase retarders have been investigated using the soft x-ray polarimeter at BESSY-II. The measured phase shift was about 42° in the wavelength range of 13.8–15.5nm, and the corresponding s-component transmission (Ts) decreased from 6% to 2% with increasing wavelength.

In this paper, double-layer surface-relief resonant Brewster filters consisting of a homogenous layer and a grating with equal refractive index are obtained by adjusting the grating filling factor, and linewidth properties of these types of filters are investigated. It is shown etch depth error does not change the filter linewidth, but the grating filling factor and the substrate refractive index can significantly change the filter linewidth. Moreover, the coupling strength can be appreciately affected by the homogeneous layer thickness, and one can obtain different linewidths at the same operating wavelength by selecting different homogeneous layer thickness with other physical parameters maintained.

In this letter, the double-layer resonant Brewster filters and their properties were presented, which consist of a homogenous layer with a refractive index equal to that of the grating. By tuning the thickness of the homogeneous layer, a multichannel resonant Brewster filter with thin grating thickness can be obtained. For this type of filters, the variety of the grating thickness almost did not change the resonance location, but had a distinct effect on the filter linewidth. By changing grating period or tuning incident angle, different linewidths can be obtained at the same resonance wavelength without losing the low-reflection sideband feature.

Broadband extreme ultraviolet molybdenum/yttrium aperiodic multilayer analyzers were designed for polarization experiments in 8.5–11.7nm wavelength range. The multilayer analyzers were made using direct current magnetron sputtering and characterized using the soft x-ray polarimeter at BESSY-II facility. Measured s reflectivities at the Brewster angle are 5.5% for a multilayer designed for 8.5–10.1nm wavelength range and 6.1% for one designed for 9.1–11.7nm. The multilayers also exhibit high polarization degree up to 98.79%. In addition, the multilayer was also measured over 38°–52° angular range at the fixed wavelength of 10.2nm and the mean s reflectivity is 6.2%.

In this letter, a type of guided-mode resonance (GMR) reflection filter incorporating multimode resonance and the Brewster effect is presented. Long-range, low sidebands, and multiple channels are found to be obtainable for a single-layer GMR reflection filter with a TM-polarized plane wave incident at the Brewster angle. Detailed characteristics are calculated using rigorous coupled-wave analysis. In our calculation, for TM-polarized incident wave, we find it sufficiently accurate to calculate the effect index by using the zero-order permittivity e0,TM of the effective media theory, and narrowband multichannel reflectance can be achieved at the Brewster angle by tuning the grating depth.

Nonperiodic molybdenum/silicon broadband multilayer polarizers have been designed using numerical optimization algorithm and fabricated using direct current magnetron sputtering. Their performances have been characterized using the high precision eight-axis soft x-ray polarimeter at the BESSY facility. Different multilayers have measured s-polarized reflectivities of 27% at 13.1nm and higher than 15% over the wavelength range of 13–19nm. Nearly constant s reflectivity, up to 37%, is observed over the 15–17nm wavelength range, where the degree of polarization is more than 98%. Furthermore, these multilayer polarizers also show high s reflectivity and polarization over a broad angular range at fixed wavelength.