  Observations close to the diffraction limit, with high Strehl ratios from
Adaptive Optics (AO)-assisted instruments mounted on ground-based telescopes
are a reality and will become even more widespread with the next generation
instruments that equip 30 meter-class telescopes. This results in a growing
interest in tools and methods to accurately reconstruct the observed Point
Spread Function (PSF) of AO systems. We will discuss the performance of the PSF
reconstruction (PSF-R) software developed in the context of the MICADO
instrument of the Extremely Large Telescope. In particular, we have recently
implemented a novel algorithm for reconstructing off-axis PSFs. In every case,
the PSF is reconstructed from AO telemetry, without making use of science
exposures. We will present the results coming from end-to-end simulations and
real AO observations, covering a wide range of observing conditions.
Specifically, the spatial variation of the PSF has been studied with different
AO-reference star magnitudes. The reconstructed PSFs are observed to match the
reference ones with a relative error in Strehl ratio and full-width at half
maximum below 10% over a field of view of the order of one arcmin, making the
proposed PSF-R method an appealing tool to assist observation analysis, and
interpretation.
