Sensing differential pistons between petals of the ELT

lundi 20 janvier 2020, par Arielle Bertrou (LESIA)

Jeudi 23 janvier 2020 à 16h00 , Lieu : Salle de conférence du bâtiment 17

The presence of a six legged 50 cm-wide spider supporting the secondary mirror of the ELT breaks the spatial continuity of the incoming wave-front. Atmospheric turbulence, low wind effect, thermo-mechanic drift of the deformable mirror are all contributors to misphasing of the six petals of the telescope. It is therefore necessary to measure these differential pistons in order to reconstruct the full wave-front.

The pyramid wave-front sensor is currently the preferred design for adaptive optics systems. However, it was shown to be a poor petal sensor in the visible and under partial turbulence correction. This talk will present results that highlight the inability to sense petal pistons given the actual design of MICADO SCAO instrument. Based on this, we investigate the possibility of a petalometer : a sensor specifically designed to answer the need for petal pistons sensing.


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