1,721,523 research outputs found
Performance analysis of the spectroscopic channel of UVISS, an ultraviolet telescope for the ISS
No full textX-ray CCD camera to detect scattered light in the experimental chamber of the ALOISA beamline
No full textDiffraction effects on very large space instruments: a detailed analysis to solar coronagraphy
No full textRecent possibility of building clusters of micro-satellites have increased the interest on extremely large space
instruments. Since this growing is not merely a change of scale, performance of these new instruments has to
be critically re-analyzed under this new perspective. As an example, diffraction effects can lead to new levels
of signal-to-noise ratio, greatly increasing the possible performance of classical optical instruments. In this
work we have analyzed the diffraction behavior of an opaque disc acting as external occulter in a space solar
coronagraph. Since the occulter can be set at great distance from the telescope, improvements on signal-to-noise
ratio are obtained. Moreover, this analysis can lead to a determination of a potential apodization function for
the occulter
HIGH-RESOLUTION SOFT-X-RAY MONOCHROMATORS OF NEW DESIGN
No full textWe have applied the principle of sagittal focusing to obtain high-resolution soft-X-ray monochromators for application to undulators, as planned for the new generation of synchrotron radiation facilities. Grazing incidence optical configurations (like Czerny-Turner and those utilizing a grating with variable line spacing) are particularly attractive. These configurations have the advantage of using fixed entrance and exit slits. We have analyzed such configurations using sagittal focusing and have shown that the resolution obtainable is comparable with that of a spherical grating monochromator of similar size (which, by contrast, needs moving entrance and exit slits). © 1990
The UltraViolet Coronagraph Spectrometer on Board the Solar and Heliospheric Observatory
No full text
Analysis of diffraction from the occulter edges of a giant externally occulted solar coronagraph
No full textA technique is described for the calculation of the intensity of the light diffracted by the occulter of an externally
occulted solar coronagraph. This technique can be applied to an occulter of generic shape, but the attention
is here focused on a specific application; that is, the case of a giant space solar coronagraph, in which the
occulter is located at 100 m from the telescope aperture. By means of the code developed, it has been possible
to simulate the effects of various shapes of the occulter edge with the aim of analyzing in detail the best
apodization for the coronagraph. The results obtained show that an occulter with a circular serrated edge allows
a remarkable reduction of the amount of diffracted light on the coronagraph’s entrance aperture with
respect to a simpler circular disk case
Design of a high-flux low-energy synchrotron radiation monochromator
No full textThe characteristics and the performance of a new design low-energy high-flux synchrotron radiation beamline are here presented. This
instrument, initially conceived for being applied to DAFNE at the Frascati electron-positron collider, has been developed for a possible
application to a fully dedicated synchrotron radiation third generation bending magnet. The beamline has a very innovative point in
locating the first optics within the accelerator tunnel to collect as much flux as possible; the light is then focused on the entrance slit of a
double normal and grazing incidence monochromator, to cover the 5–200 eV energy range; finally, a refocusing system collects the light
from the monochromator exit slit and focuses it on the sample under study. The goal of this beamline is to deliver an high flux of photons
in the energy range 5–200 eV with a resolution R larger than 10 000 for energy range 5–20 eV, and larger than 3000 for the range
30–200 eV. With this performance, the flux delivered is comparable to the one obtained by existing undulator beamlines: this shows that
placing the first optical element as close as possible to the ring guarantees the required performance without the need of a straight section
and an undulator
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