Thanks! see attached the screenshot with distorted lines at two different places of the screen. I am not totally sure but it seems that such a problem is arising when the screen content is getting changed dynamically, for example, when I write text (see the second attachment). Best regards, Mushegh Rafayelyan Postdoctoral researcher at Kastler-Brossel Laboratory (ENS, Sorbonne U., CNRS, Collège de France) http://www.lkb.upmc.fr/opticalimaging/ On Mon, 7 Jan 2019 at 10:31, Daniel van Vugt