An optical system for measuring position and acceleration of the sliding bow of a pantograph, and the contact force between the sliding bow and the catenary suspension line, comprising: at least a camera installed on the ceiling of a railway vehicle and configured so that a region containing at least a portion of said sliding bow is framed; at least a laser focused on a laser sheet arranged on a substantially vertical plane and directed towards said pantograph, said laser sheet intersecting said region framed by said camera, at least a target installed integrally to said sliding bow. The system is characterized in that, in order to increase the intensity of light reflected towards the camera, said target is cylindrical, realized in material reflecting to the frequency of the light emitted by said laser and positioned with its axis parallel to the sliding bow axis, in a position where it is lighted by said laser and framed by said camera.