Thesis

Wide-field Adaptive-Optics-corrected PSF reconstruction

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domain:

  Astrophysics

• Supervisor:

  Paulo Garcia

• Co-Supervisor:

  Carlos M Correia

• Institution:

  Universidade do Porto

• Host Institution:

  SIM/FEUP

• Abstract:

  Adaptive optics (AO) is an emerging domain where accurate photometry and astrometry is becoming a key challenge and promise. AO relies on the real time correction of atmospheric aberrations introduced in the wavefront. The classical concept is a wavefront sensor sensing a reference star and driving a deformable mirror. It delivers an optimal point spread function (PSF) towards the reference axis (on-axis) but it degrades away from the axis, a consequence of the reference only sampling the on-axis turbulence and of the de-correlation of turbulence for larger distances (angular anisoplanatism). Therefore the PSF is variable across the field-of-view. This is a strong limitation for the “classical” single conjugate adaptive optics as many astronomical applications require fields in excess of the few isoplanatic arcseconds. On the other hand this limitation is in a way similar to the much larger field (arcminutes) PSF variation observed in classical photometry. The post-processing of adaptive optics data is a critical step in its astrophysical exploitation. Post-processing covers many aspects, mainly data deconvolution of individual extended objects and, most importantly in the context of the present project, photometric/astrometric extraction of stellar fields via PSF fitting codes. Most codes applied for photometric exploitation of AO fields are those available for standard non-AO photometry. The challenges brought by adaptive optics and also by non-adaptive optics off-axis images are inevitable in the increasingly large focal planes and in the case of the European Extremely Large Telescope with ~40m segmented diameter as set forth in the ASTRONET roadmap and OPTICON technology programme. Addressing these challenges is the subject of this proposal. Profile: Student with strong interest in astrophysics, optics/propagation, mathematical modelling, statistical physics, numerical simulations, data/signal processing. The work will accompany developments within the OPTICON framework and similar activities at LAM – Laboratoire d'Astrophysique de Marseille; availability of potential candidates to spend time in Marseille is required. References: Gilles, Correia et al, Simulation model based approach for long exposure atmospheric point spread function reconstruction for laser guide star multiconjugate adaptive optics, Applied Optics, vol. 51, issue 31, p. 7443 http://dx.doi.org/10.1364/AO.51.007443 Gilles, Correia et al, Tip/tilt point spread function reconstruction for laser guide star multi-conjugate adaptive optics, SPIE 2012, http://dx.doi.org/10.1117/12.926928