  Laser Guide Star (LGS) Shack-Hartmann (SH) wavefront sensors for next
generation Extremely Large Telescopes (ELTs) require low-noise, large format
(about 1Mpx), fast detectors to match the need for a large number of
subapertures and a good sampling of the very elongated spots. One path
envisaged to fulfill this need has been the adoption of CMOS detectors with a
rolling shutter read-out scheme, that allows low read-out noise and fast
readout time at the cost of image distortion due to the detector rows exposed
in different moments. In this work we analyze the impact of the rolling shutter
read-out scheme when used for LGS SH wavefront sensing of the Multiconjugate
adaptive Optic Relay For ELT Observations (MORFEO, formerly known as MAORY) for
ESO ELT; in particular, we focus on the impact on the adaptive optics
correction of the distortion-induced aberrations created by the rolling
exposure in the case of fast varying aberrations, like the ones coming from the
LGS tilt jitter due to the up-link propagation of laser beams. We show that the
LGS jitter-induced aberration for MORFEO can be as large as 100nm rms and we
discuss possible mitigation strategies.
