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A proposal to equip the TNG with a OV coronagraph

A proposal to equip the TNG with a OV coronagraph. C. Barbieri. OV Coronagraph concept - 1. OV Coronagraph concept - 2. OV Coronagraph concept - 3. OV Coronagraph concept - 4. AdOpt module: a crucial addition.

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A proposal to equip the TNG with a OV coronagraph

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  1. A proposal to equip the TNG with a OV coronagraph C. Barbieri

  2. OV Coronagraph concept - 1

  3. OV Coronagraph concept - 2

  4. OV Coronagraph concept - 3

  5. OV Coronagraph concept - 4

  6. AdOpt module: a crucial addition There is no hope to reach a decent contrast unless the atmospheric degradation (seeing, scintillation) is corrected for, by means of a suitable AdOpt module.

  7. A first analysis of AdOpt characteristics Color coding: red  = 0.8 µm, green  = 0.6 µmContinuous line: 250 Hz , dotted line: 500 HzSymbols: Triangle 32 actuators (6 on diameter) , square 60 actuators (8 on diameter) Strehl Ratio for an aperture diameter D = 1.2m The analysis shows that an aperture of 1.2m can be corrected with an AdOpt module able to achieve a Strehl ratio around 0.3 – 0.4 in the near-IR. The module is certainly difficult and expensive (60 actuators, 500 Hz) but doable.

  8. The TNG The angle between the spiders is 56.25deg; as a result a pupil of 1.2m in diameter will span an "unobstructed" angle of 82 deg (as a last and first contact to the spiders). The thickness of the spiders is 20 mm

  9. Available space

  10. The second approximation design with the off-axis AdOpt module

  11. TNG OV coronagraph optics

  12. First Mechanical Concept

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