| Issue |
EAS Publications Series
Volume 12, 2004
Astronomy with High Contrast Imaging II
|
|
|---|---|---|
| Page(s) | 205 - 211 | |
| DOI | https://doi.org/10.1051/eas:2004034 | |
| Published online | 29 August 2011 | |
C. Aime and R. Soummer (eds)
EAS Publications Series, 12 (2004) 205-211
Hg-Mask Coronagraph
1
Observatório Nacional - Rio de Janeiro, Brazil
2
OCA - Nice, France
3
IMCCE - Paris, France
In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).
© EAS, EDP Sciences, 2004