We report on the design and fabrication of a reflection grating for hyperspectral applications operating in the range from 340 nm to 1040 nm wavelength. The blazed grating is based on an effective medium approach, where the desired functionality is realized using a binary surface relief structure. For each period, a gradient in size of the local grating features mimics an interface which adds a linear phase profile to the illuminating beam – thus introducing diffraction. The surface relief structure is composed of 2D structures - pillars with diameters from 200 nm to 350 nm to voids with diameters from 300nm to 120 nm. Overall, an entire number of ~50 such features are arranged to establish an overall unit cell of the grating over a length of 30 μm. By purposeful design of size, shape and arrangement of the sub-wavelength features such gratings offer novel opportunities in tailoring the spectral response, i.e. particular broadband efficiency or the enhancement of the efficiency in specific sub-domains of the spectrum. We will present measured performance results of a grating covering a circular area of 80mm in diameter manufactured on a 4inch-wafer. Finally, we will give an outlook on how such structures can be applied to curved surfaces and even ultra-broadband operation.
Sentinel-5 is an atmospheric monitoring mission within the European Copernicus programme, formerly GMES (Global Monitoring for Environment and Security). Its main objective is trace-gas and aerosol optical depth measurements for air quality and climate monitoring and forecast with daily global coverage. Constituents of interest are O<sub>3</sub>, SO<sub>2</sub>, HCHO (formaldehyde), BrO, NO<sub>2</sub>, CHCHO (glyoxal), O<sub>2</sub>, CH<sub>4</sub> (methane), and CO. Sentinel-5 will complement the Sentinel-4 GEO data over Europe. Both Sentinel-4 and -5 are intended to start operation in 2020.
The objective of this paper is to assess how variations of the chief ray angle of the illumination light incident on an EUV multilayer mask as well as the light bandwidth affect the performance of an AIMS EUV tool with respect to CD measurement and defect evaluation. To this end EUV images were simulated with an EUV lithography simulator developed by the Fraunhofer Institute IISB. The simulations were performed for a multilayer mask with a buried defect under an isolated line. The specifics of the AIMS EUV were taken into account by a superposition of aerial images obtained for different wavelengths. The presentation discusses the simulations and their results.
Multivariate quantitative analysis of FTIR-spectra requires that the spectral line shapes of sample spectrum and spectral reference, and hence, the respective instrumental line shape (ILS) functions, match as closely as possible. In open-path measurements, the ILS' generally differ because of the differences in the optical geometry of the setups, or in the case of synthetic reference spectra, because the ILS cannot exactly be determined from the measuring parameter. In particular, when using large field stop diameters the line shapes can deviate considerably. Therefore, a mathematical method to approximate the ILS based on a parametrical identification has been developed and integrated into an algorithm for quantitative multivariate analysis. This article gives an overview over the parametrical model of the ILS approximation and its integration in the spectral evaluation algorithm, and presents results of their application to transmission spectra of extractive and open-path exhaust gas measurements.