This paper, “PIMACS (Polarimeter and improved modular anti-coincidence system): an effective instrument concept for x-, gamma-ray monitoring, and polarimetry measurements on the International Space Station," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
This paper, “Optimized technical and scientific design approach for high performance anticoincidence shields," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
KEYWORDS: Sensors, Telescopes, Space telescopes, Fermium, Frequency modulation, Calibration, Optical testing, Interferometers, Detection and tracking algorithms, Point spread functions
The objective of the so-called fringe sensor DWARF - derived from DARWIN AstRonomical Fringe Sensor is to measure all relevant perturbations and to provide real time control data to achieve co-phasing of the freeflying telescopes of the DARWIN system. An overview of the design of the sensor Breadboard (BB), as it has been designed and built at Kayser-Threde as Prime with main partners ONERA and Alcatel Space under ESA contract 17012/03/NL/EC is presented. An extensive test campaign has been carried out at ONERA. The respective optical test setup is outlined and the achieved performances for retrieval of primary and higher order aberrations are presented. As final outcome of the BB study the essential elements to build a fringe sensor (FS) flight model are shortly characterized and the respective development roadmap is sketched.
Scientific experiments on mineral and biological samples with Raman excitation below 300nm show a wealth of scientific information. The fluorescence, which typically decreases signal quality in the visual or near infrared wavelength regime can be avoided with deep ultraviolet excitation. This wavelength regime is therefore regarded as highly attractive for a compact high performance Raman spectrometer for in-situ planetary research. Main objective of the MIRAS II breadboard activity presented here (MIRAS: Mineral Investigation with Raman Spectroscopy) is to evaluate, design and build a compact fiber coupled deep-UV Raman system breadboard. Additionally, the Raman system is combined with an innovative scanning microscope system to allow effective auto-focusing and autonomous orientation on the sample surface for high precise positioning or high resolution Raman mapping.
Imaging spectrometers featuring a grating disperser allow for a compact system design. However, due to the limited
diffraction efficiency of the grating these instruments suffer from low throughput and high sensitivity to polarization.
Prism spectrometers do not have these disadvantages, but they show a low angular dispersion with noticeable non-linearity,
which is the main driver of the overall spectrometer dimensions. The envelope of a prism spectrometer can be
significantly decreased when prisms with curved surfaces are used. They allow for a reconfiguration of the concentric
Offner relay which is well known for its good imaging quality and its low distortion. In the document at hand a novel
type of compact Offner spectrometers with curved prisms is presented. As an example the optic design of EnMAP, a
German space born hyperspectral imager is given.
The Environmental Mapping and Analysis Program (EnMAP) is a German space based hyperspectral mission planned
for launch in 2012. The hyperspectral instrument covers the wavelength range from 420nm to 2450nm using a dual
spectrometer layout. Both f/3 spectrometers employ a prism disperser for maximum throughput and are linked to the
common foreoptics by a micromechanical field splitter. Together with custom designed silicon and MCT-based detector
arrays this sensor design exhibits a peak system SNR of 1000 at 495nm and of more than 300 at 2200nm. Stable and
precise in orbit performance is ensured by a multi loop thermal control system and a system calibration which relies on
onboard sources as well as a full aperture diffuser.
The Environmental Mapping and Analysis Program (EnMAP1,2) is a joint response of German Earth observation research institutions, value-adding (VA) resellers and space industry to the increasing demand on accurate, quantitative information about the evolution of terrestrial ecosystems. With its hyperspectral capabilities covering the visible, near- and short-wave infrared wavelengths, EnMAP will provide high quality, standardized, and consistent data on a timely and frequent basis. Its primary focus will be on the considerable improvement of already standardized products and the development of new quantitative and highly informative data and its derivatives. Only an imaging spectrometer, such as EnMAP, can resolve and detect biophysical, biochemical, and geochemical variables in distinct detail. This will tremendously increase our understanding of coupled biospheric and geospheric processes and thus, enable the management to ensure the sustainability of our vital resources.
After a successfully accomplished phase A, EnMAP has been approved by the German Aerospace Agency in the beginning of 2006. The instrument performance allows for a detailed monitoring, characterisation and parameter extraction of vegetation targets, rock/soils, and inland and coastal waters on a global scale. By the scientific lead of the GeoForschungsZentrum Potsdam (GFZ) and the industrial prime ship of Kayser-Threde, the ongoing planning aims towards an internationalisation of the mission approach.
The EnMAP instrument provides information based on 218 contiguous spectral bands in the wavelength range from 420 nm to 2450 nm. It is characterized by a SNR of > 500:1 in the VNIR and an SNR of >150:1 in the SWIR range at a ground resolution of 30 m x 30 m.
While investigating the feasibility of the accommodation of X-ray instrumentations on the International Space Station (ISS) a major question remained still open, i.e. the unknown extent of degradation of X-ray mirror surfaces and X-ray detector material caused by contamination in the ISS environment. Therefore, a sample expose experiment has been started in 2001 to investigate these effects in detail using the Russian expose facility provided by the Russian space industry company RKK Energia. While Kayser-Threde GmbH was responsible to organize and coordinate the experiment, gold-coated Zerodur and silicon samples have been provided by the Max-Planck-Institute (MPE). In total 5 samples were flown with the expose facility and have been exposed to the ISS environment for a total duration of 756 days. The analyses of 4 of them are presented in this paper. X-ray reflection measurements before and after the experiment at MPE's PANTER X-ray test facility and microscopy inspections revealed a thin structured surface layer which reduced the X-ray reflection of the exposed mirror samples dramatically. In addition, the samples have been analyzed with a scanning electron microscope, an energy dispersive X-ray spectrometer, and electron spectroscopy for chemical analysis. The results of all these measurements revealing the degradation of the X-ray mirrors and polished silicon detector surfaces are presented.
The mission ROSITA (ROentgen Survey with an Imaging Telescope Array) will perform the first imaging all-sky survey in the medium energy X-ray range up to 10 keV with an unprecedented spectral and angular resolution. Thus, ROSITA leads to an improved understanding of obscured black holes in Active Galactic Nuclei. In addition, ROSITA represents an important pathfinder for beyond 2015 space telescopes like XEUS and Constellation X. Targeting for a flight in 2008/2009 on one side ROSITA is considered as technology test bed for later X-ray cornerstone missions, on the other side the measurement data will form a good basis for later detailed surveys with the corresponding high resolution pointing systems.
For the measurement of astronomical gamma ray radiation in the energy range 50 keV to several MeV usually photomultiplier tubes (PMT) with scintillation crystals are used. However, due to the internal detection mechanism high voltage and single photon counting are required leading to heavy and structurally unpractical systems. Even APD's (avalanche photodiodes) do not circumvent the problem of the high voltage. Recent improvements in the performance of semiconductor detectors allow the use of large area and low noise pin photodiodes as innovative scintillation detectors with 40 - 100 V operating voltage only. Tl-doped CsI as scintillation crystal with a superior light yield has not only a much higher photon output compared to the light yield of pure CsI and BGO crystals which are used for the gamma ray detection with PMTs, but has also a perfect matching of spectral properties of the photodiode. This paper presents a comprehensive comparison with conventional PMT scintillation detector systems and the development activities of full size breadboards with such a photodiode/CsI(Tl) detector set-up. The relevant functional performance test results have shown the high technical maturity of this detector system and the principal feasibility for the application either in the INTEGRAL spectrometer and imager anticoincidence shield (ACS) or in image central detector system. The dedicated ACS configuration design featuring optimized mass budget combined with high gamma ray stopping efficiency is figured.
The sensitivity of a CO2-lidar system using the DAS-technique is based on the smallness of two different errors: the DAS measurement error and the error in the absorption coefficient. The first one is given by the system stability and the influence of the atmosphere on the return signal of the lidar, meanwhile the spectral characteristic of the laser radiation and the accuracy of the measurement set up are responsible for the error in the detection limits. The combination of both errors is responsible for the total measurement accuracy. This is important for the comparison of the measurement results with those of a FTIR-spectrometer. Due to a difference in the measurement principle, the spectrometer offers the advantage of a wide, continuous coverage of the spectrum (2-15 micrometers - depending on the used detector), but the usable range is restricted to a maximum distance of about 500m. This tunable lidar- system however can be used for measurement distances of up to 5 km, but is limited on a nubmer of discrete wavelengths.
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