Devices for measuring the surface state of a surface, at least one portion of which has a surface curvature. The devices may include a probe for being in contact with the curved surface portion. The probe may be stressed on the surface with a substantially constant stress. A way to measure the displacement of the probe may be provided and arranged to measure the displacement of the probe along an axis substantially perpendicular to the surface. The probe may also be relatively displaced in relation to the surface only along a path following the surface curvature.