Search results for "Filters"
showing 10 items of 92 documents
Wavelength-flattened directional couplers for mirror-symmetric interferometers
2005
In the context of guided optics, we derive, analytically and geometrically, a rigorous general criterion to design wavelength insensitive interferometers with mirror symmetry, which are needed for wavelength multiplexing/demultiplexing. The criterion is applied to a practical case, resulting in an interferometer that works on a band wider than 70 nm.
The filter wheel and filters development for the X-IFU instruments onboard Athena
2016
Athena is the large mission selected by ESA in 2013 to investigate the science theme “Hot and Energetic Universe” and presently scheduled for launch in 2028. One of the two instruments located at the focus of the 12 m-long Athena telescope is the X-ray Integral Field Unit (X-IFU). This is an array of TES microcalorimeters that will be operated at temperatures of 50 mK in order to perform high resolution spectroscopy with an energy resolution down to 2.5 eV at energies < 7 keV. In order to cope with the large dynamical range of X-ray fluxes spanned by the celestial objects Athena will be observing, the X-IFU will be equipped with a filter wheel. This will allow the user to fine tune the i…
Status of the EPIC thin and medium filters on-board XMM-Newton after more than 10 years of operation II: analysis of in-flight data
2013
After more than ten years of operation of the EPIC camera on board the X-ray observatory XMM-Newton we have reviewed the status of its thin and medium filters by performing both analysis of data collected in-flight and laboratory measurements on on-ground back-up filters. We have investigated the status of the EPIC thin and medium filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission of the filters. We both investigated repeated observations of single optically bright targets and performed a statistical analysis of the extent of loading versus visual magnitude at different epochs. We report the results of these …
Integration of local features into a global shape
2001
AbstractIt is a well-established fact that the cortical filters selective for spatial frequency and orientation have a limited spatial extent. The present study investigated how information from local filters is integrated into global shapes. Specifically, we were interested in whether identification of a global pattern consisting of small oriented, spatially-bandpass features (Gabor patches) depends on the orientations of those features. The observer was presented with a C-like stimulus shape comprised of oriented Gabor elements on a blank background, and the performance measure was the threshold contrast for identifying the global orientation of the C-shape (four possible rotated orientat…
A comparison of micropore membrane inlet mass spectrometry–derived pulmonary shunt measurement with riley shunt in a porcine model
2009
The multiple inert gas elimination technique was developed to measure shunt and the ratio of alveolar ventilation to simultaneous alveolar capillary blood flow in any part of the lung (V(A)'/Q') distributions. Micropore membrane inlet mass spectrometry (MMIMS), instead of gas chromatography, has been introduced for inert gas measurement and shunt determination in a rabbit lung model. However, agreement with a frequently used and accepted method for quantifying deficits in arterial oxygenation has not been established. We compared MMIMS-derived shunt (M-S) as a fraction of total cardiac output (CO) with Riley shunt (R-S) derived from the R-S formula in a porcine lung injury model.To allow a …
Modulation of endotoxin-induced neutrophil transendothelial migration by alveolar epithelium in a defined bilayer model.
2006
Within the alveolus, epithelial cells, due to their close association with endothelial cells, can potentially influence endothelial cell responsiveness during inflammation and their interaction with leukocytes. To investigate this, three lung epithelial cell lines (A549, Calu-3, or NCI-H441) were grown with endothelium on opposing surfaces of Transwell filters and the formation and stability of bilayers was rigorously evaluated. All epithelial lines disrupted endothelial monolayer formation on filters with 3- or 5-microm pores by breaching the filter, and this occurred regardless of seeding density, matrix composition, or duration of culture. Endothelial disruption was not detectable by ele…
Progress in the management of acute pulmonary embolism.
2015
Purpose of review Pulmonary embolism is a major contributor to global disease burden worldwide. The 2014 guidelines of the European Society of Cardiology, endorsed by the European Respiratory Society, emphasize the need for initial and advanced risk stratification as well as risk-adapted treatment to ensure the highest quality of care. This review summarizes the progress in pulmonary embolism diagnosis, risk assessment, and treatment. Recent findings Major advances of the past 12 months include age-related biomarker cutoff levels for optimising pulmonary embolism diagnosis and risk stratification; detection of (isolated) subsegmental pulmonary embolism by computed tomographic pulmonary angi…
The Space Weather X-Ray spectrometer for the Helianthus sub-L1 mission with solar photonic propulsion
2022
Copyright 2022 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited. Helianthus is a phase A study of a space weather station with solar photonic propulsion. The scientific payload will be made of: an X-ray spectrometer to detect solar flares; SailCor, a coronagraph with a wide field of view; a plasma analyzer; a magnetometer. The maximum allowed mass for the entire scientific payload shall not exceed 5 kg. The two imaging devices…
Carbon nanotubes thin filters for x-ray detectors in space
2022
In this paper, we present the first results from an investigation performed on nanometric thin pellicles based on carbon nanotubes (CNT) of potential interest for manufacturing large area optical blocking filters to protect soft X-ray detectors in astrophysics space missions. In order to evaluate the effective capability of such materials to block UV/VIS/IR radiation, while being highly transparent in the soft X-rays and strong enough to withstand the severe launch stresses, we have performed a suite of characterization measurements. These include: UV/VIS/IR and X-ray absorption spectroscopy, X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy on bare and Al coated small self-…
X-Ray microcalorimeter detectors - Technology developments for high energy astrophysics space missions
2020
Improvements in the design, fabrication, and performance of astronomical detectors has ushered in the so-called era of multi messenger astrophysics, in which several different signals (electromagnetic waves, gravitational waves, neutrinos, cosmic rays) are processed to obtain detailed descriptions of their sources. Soft x-ray instrumentation has been developed in the last decades and used on board numerous space missions. This has allowed a deep understanding of several physical phenomena taking place in astrophysical sources of different scales from normal stars to galaxy clusters and huge black holes. On the other hand, imaging and spectral capabilities in the the hard x-rays are still la…