Among other things, a first surface is configured to receive a sample and is to be used in a microscopy device. There is a second surface to be moved into a predefined position relative to the first surface to form a sample space that is between the first surface and the second surface and contains at least part of the sample. There is a mechanism configured to move the second surface from an initial position into the predefined position to form the sample space. When the sample is in place on the first surface, the motion of the second surface includes a trajectory that is not solely a linear motion of the second surface towards the first surface.