Tropomi, successfully launched in October 2017, and Sentinel-5, with launch due in 2021, are two pushbroom spectrometers measuring Earth's radiance from a Low Earth Orbit (LEO) at a high spectral resolution. Both instruments have strongly overlapping spectral channels (UV-VIS, NIR, SWIR-3). While the Tropomi spectrometers are designed with standard slits, all Sentinel-5 channels make use of complex slit assemblies called "slit homogenizers" that aim at mitigating the slit heterogeneous illumination that results from the along track spatial non-uniformity of the observed scenes, and is known to distort the instrument spectral response function (ISRF). The similarity between the two missions will allow, in a few years from now, to evaluate the performance gain resulting from these devices. If their expected success is confirmed, slit homogenizers may become standard components of future space missions. This paper aims at providing a comprehensive, yet as simple and accessible as possible, overview of the slit homogenizer performance. The Sentinel-5 slit homogenizers, based on two parallel mirrors will be discussed, and a new and promising family of slit homogenizer designs will be presented for the first time. The new designs offer several advantages in terms of performance and manufacturability.
Summary:Purpose: To show that colitis may be part of the antiepileptic hypersensitivity syndrome.Methods: Description of two case histories.Results: The first patient was a 47-year-old man who developed fever, lymphadenopathy, influenza-like symptoms, facial edema, skin rash and diarrhea after 3 weeks of carbamazepine (CBZ) treatment. Laparotomy because of severe abdominal pain 2 weeks later showed severe colitis with perforations. The second patient was a 41-year-old woman who developed fever, diarrhea, and skin rash 4 weeks after start of CBZ treatment. A colon biopsy confirmed colitis. Stool examinations did not show pathogenic microorganisms, and there was no evidence of Crohn's disease or ulcerative colitis. Both patients had elevated liver enzymes, peripheral eosinophilia, and eosinophils in the infiltrate of the colon.Conclusions: In view of the close temporal relation between start of CBZ intake and development of colitis, the presence of fever, lymphadenopathy, and rash, and improvement after discontinuation of CBZ, we conclude that the two patients developed an AED hypersensitivity syndrome. Our case histories demonstrate that severe colitis may be part of this syndrome.
We have developed a novel diffraction grating based on lithographical techniques and anisotropic etching in silicon. The grating is designed for the short-wave-infrared channel of the TROPOMI imaging spectrometer that will be launched on ESA's Sentinel 5 Precursor mission to monitor trace gases in the earth atmosphere. Stringent requirements on both the imaging properties and the quality of the spectra translate to a high-tech grating. In our design the dispersion and resolution is increased with a factor 3.4 with respect to conventional gratings by using the grating in immersion, such that diffraction takes place inside the silicon grating material. By lithographic patterning and anisotropic etching of the mono-crystalline silicon we precisely control line spacing and blaze angle. The grating has a line spacing of 2.5 μm and is operated in sixth order. We show that an efficiency of 60% is reached on a 50 x 60 mm 2 grating surface. We compare our test results with numerical calculations for grating efficiency for both polarizations and find good agreement.
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