Basic Formulae of XUV Multilayer Optics

Кожевников, И. В.; Виноградов, А. В.

doi:10.1088/0031-8949/1987/t17/015

Cited by 58 publications

(46 citation statements)

References 12 publications

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“…at energies between roughly 100 and 1500 eV. Unfortunately, the spectral resolution of ML mirrors in this regime is inherently limited by absorption of the fluorescent x-rays that need to be analyzed [4][5][6][7]. Although the natural line widths of fluorescent x-rays are typically E/ΔE ≈ 1000 [8], closely spaced lines could often not be distinguished due to the limited resolution of the analyzing optical element.…”

Section: Motivationmentioning

confidence: 99%

“…From this figure, it can easily be seen that silicon is an excellent candidate as low-Z material. The optimal high-Z material can then be chosen by maximizing the modulation-over-absorption ratio Λ = Re| A − S |/Im( A ), where is the dielectric constant given by n = √ [4]. This is demonstrated in figure 1.2b for the SXR energy of 1 keV and assuming silicon to be the spacer layer.…”

Section: Multilayer Mirrorsmentioning

confidence: 99%

“…For a diffraction order to exist, constructive interference should not only occur between waves emitted from neighboring lines, but also from all waves emitted from within a single line. The variation in irradiance I due to the interference from the single lines is described by Fraunhofer diffraction [14]: 4) where k = 2π/λ and b is the line width. From this equation, angles of destructive interference from a single grating line can be determined to occur at [14]: 5) where M indicates the diffraction order from a single line.…”

Section: Diffractive Opticsmentioning

confidence: 99%

“…As previously mentioned, the spectral resolution of ML mirrors in the SXR region is determined by N ef f and is inherently limited due to absorption [4]. The effective density, i.e.…”

Section: Lamellar Multilayer Gratingsmentioning

confidence: 99%

“…We also show that the resolution of an LMG operating in single-order regime is not limited by absorption, in contrast to the resolution of a conventional ML mirror. A high resolution and high reflectivity have been shown to be mutually exclusive for a ML mirror [4], whereas the resolution of an LMG is only limited by technological factors and the peak reflectivity can still be as high as for a conventional ML mirror.…”

Section: Introductionmentioning

confidence: 99%

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Single-order lamellar multilayer gratings

Meer¹

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Cover: 3D artist impression of a Lamellar Multilayer Grating (LMG). A Transmission Electron Microscope image of an actual LMG is shown on the rear. The grating was etched into a 400 bi-layer W/Si multilayer mirror with a total stack height H of 1 μm and a tungsten layer thickness of only 3 atoms. The grating had a period D of 300 nm and a lamel width ΓD of 75 nm. In comparison to the TEM image on the rear, the red and green layers in the artist impression correspond to tungsten and silicon, respectively. The bi-layer period in the artist impression is overestimated by a factor of 10 for visibility. SummaryA major challenge in the soft x-ray (SXR) and eXtreme UltraViolet (XUV) spectral ranges is the ability to manipulate the incident radiation using optical elements. By patterning conventional multilayer mirrors with nanoscale structures, novel optical elements with a variety of optical properties can be obtained. In this work, the design, fabrication and characterization of Lamellar Multilayer Gratings (LMG) was investigated. Such LMGs are a particular form of the general class of Bragg-Fresnel optics which combine Fresnel optics with Bragg reflection to provide unique dispersive and focusing optics. In particular, LMGs can be used to improve the spectral resolution of x-ray fluorescence techniques.A Coupled Waves Approach (CWA) was derived to simulate the optical performance, in terms of resolution and reflectivity, of LMGs. This CWA allowed to study the physical principles behind LMGs and resulted in the identification of an optimal LMG operating regime. In this regime, the incident beam is reflected in a single diffraction order and is hence referred to as the singleorder regime. Such single-order LMGs were fabricated using UV-NanoImprint Lithography and Bosch Deep Reactive Ion Etching, a process chosen to enable rapid practical development. Single-order operation was experimentally demonstrated and showed an improvement in spectral resolution of a factor of 3.8 with regard to conventional multilayer mirrors. Singe-order excitation of higher diffraction orders was also measured and analyzed.Single-order operation often requires multilayer stacks and grating structures that cannot be fabricated with sufficient accuracy using current technologies. As this invalidates the semi-infinite multilayer approximation, we investigated the optical performance of LMGs with finite multilayer stacks. We determined the ratio between the absorber thickness and bi-layer period of the multilayer stack can be used to further tailor LMG optical performance to maximize bandwidth reduction or minimize peak reflectivity loss. We also investigated various degradation processes that could limit the lifetime of LMGs, which is important for the applicability of such elements. Oxidation of tungsten and silicon as well as changes to the sidewall composition were clearly seen. However, SXR reflectivity remained stable to within measurement accuracy for an extended storage period of 18 months in a 1 atm air environment. The possibility of ...

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Section: Motivationmentioning

confidence: 99%

Section: Multilayer Mirrorsmentioning

confidence: 99%

Section: Diffractive Opticsmentioning

confidence: 99%

“…As previously mentioned, the spectral resolution of ML mirrors in the SXR region is determined by N ef f and is inherently limited due to absorption [4]. The effective density, i.e.…”

Section: Lamellar Multilayer Gratingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Single-order lamellar multilayer gratings

Meer¹

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Structure and optical properties of multilayer X‐ray mirrors for long wave part (3.1–4.4 nm) of “water window”

Fedorenko¹,

Кондратенко²,

Pershin³

et al. 1994

Cryst. Res. Technol.

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Structure and optical properties (at 1 = 0.154 nm and A = 3.16 nm) of W-Ti, W-TIN, W-Sc, and Cr-Sc multilayer X-ray mirrors for long wave part of "water window" wavelength range (3.1 -4.4 nm) were studied by methods of X-ray diffractometry and cross-sectional electron microscopy. The reflectivities at 1 = 0.154 nm are increased going from W -TIN, Cr-Sc, W -Ti to W -Sc multilayers. Cr-Sc mirrors have highest reflectivity and resolution at A = 3.16nm. Influence of the ambient atmosphere on optical properties of multilayer mirrors is shown. Results and discussionResults of theoretically calculated normal incidence reflectivities, R,, using (HENKE et al.; KOZHEVNIKOV et al.), as a function of soft X-ray wavelength, 1, for four MXMs with an ideal structure and with optical constants of bulk materials are shown in Figure 1. In the wavelength range of interest, Cr-Sc MXM has the highest reflectivities, then in the decreasing order of the efficiency it is followed by W -Sc, W -Ti, and W -TiN multilayers. 80'

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Thomas-fermi approach to the theory of optical constants in the XUV range

Tolstikhin

Виноградов

1990

Appl. Phys. B

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Basic Formulae of XUV Multilayer Optics

Cited by 58 publications

References 12 publications

Single-order lamellar multilayer gratings

Single-order lamellar multilayer gratings

Structure and optical properties of multilayer X‐ray mirrors for long wave part (3.1–4.4 nm) of “water window”

Thomas-fermi approach to the theory of optical constants in the XUV range

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