Recent advances in stray light modeling for large telescope/observatory systems

2018 ◽  
Author(s):  
Scott Ellis ◽  
Stephen M. Pompea ◽  
Richard N. Pfisterer
Keyword(s):  
Stray Light ◽  
Large Telescope ◽  
Recent Advances ◽  
Light Modeling

Predictions Of Stray Light Modeling On The Ultimate Performance Of Acousto-Optic Processors

1989 ◽  
Vol 28 (12) ◽  
Author(s):  
R. B. Brown ◽  
A. E. Craig ◽  
John N. Lee
Keyword(s):  
Stray Light ◽  
Light Modeling

scholarly journals Advanced Abrasive Processes for Manufacturing Prototype Mirror Segments for the World’s Largest Telescope

2014 ◽  
Vol 1017 ◽  
pp. 532-538 ◽  
Author(s):  
David Walker ◽  
Gary Davies ◽  
Tony Fox-Leonard ◽  
Caroline Gray ◽  
John Mitchell ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Stray Light ◽  
Large Telescope ◽  
Form Accuracy ◽  
Hexagonal Shape ◽  
Active Mirror ◽  
First Time ◽  
Number Of Segments

This paper describes the application of loose-abrasive processes to the manufacture of 1.4 meter, off-axis aspheric, hexagonal mirror-segments. These are prototypes for the 39 m European Extremely Large Telescope (E-ELT). The application of active forces to correct the overall form of segments in the telescope, means that the overall form-accuracy achieved in polishing can be less critical than for a non-active mirror. However, it is a requirement that the base-radii and conic constants of mirror-segments are very closely matched, so that the combined image is not degraded. This means that abrasive processes have to operate with respect to anabsoluterather thanrelativedatum. Furthermore, there are stringent requirements on mid-spatial frequency defects on segment surfaces, and on edge-roll. These control stray-light, and ultimately detectability of faint astronomical targets. We describe the CNC abrasive techniques we have developed in response. We then demonstrate the success of the approach, which represents the first time ever that segments have been processed entirely in the hexagonal shape:- a milestone in loose-abrasive processing. Finally, we address up-scale for the unprecedented number of segments required for the E-ELT build-phase.

The different (yet similar) realms of illumination and stray light modeling

2015 ◽  
Author(s):  
Edward Freniere ◽  
Michael A. Gauvin ◽  
Richard N. Youngworth
Keyword(s):  
Stray Light ◽  
Light Modeling

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

B. Large Telescope Engineering Operations

1966 ◽  
Vol 27 ◽  
pp. 200-209
Keyword(s):  
Large Telescope ◽  
Advance Planning

Whitford : The next phase of the program has to do with advance planning of the instruments themselves, to make the logistics of operation simple and foolproof. I call first on Mr Rule to speak on ‘thinking ahead’.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

2020 ◽  
Vol 7 (8) ◽  
pp. 1022-1060 ◽  
Author(s):  
Wenbo Ma ◽  
Nikolaos Kaplaneris ◽  
Xinyue Fang ◽  
Linghui Gu ◽  
Ruhuai Mei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Recent Advances ◽  
Site Selectivity ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

This review summarizes recent advances in C–S and C–Se formations via transition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

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