An analysis device, possibly having an electrostatic and/or magnetic lens, analyzes the energy of charged particles and has an opposing field grid device to which a voltage is applied in such a way that a portion of the charged particles is reflected by the opposing field grid device. Another portion of the charged particles passes through the opposing field grid device and is detected by a detector. The opposing field grid device has a curvature. A center of curvature is an intersection point of an optical axis with the opposing field grid device. The curvature has a radius of curvature which is given by the section between the center of curvature and a starting point on the optical axis. The opposing field grid device is curved in the direction of the starting point as viewed from the center of curvature and/or is arranged to be displaceable along the optical axis.