An electrostatic energy filter module that includes a (i) biasing circuit, (ii) distal electrodes, (iii) intermediate electrodes that are upstream to the distal electrodes; and (iv) proximal electrodes that are upstream to the intermediate electrodes. The electrodes are disk-shaped, concentric, are parallel to each other and define an
optical axis. The distal electrodes are configured to receive first biasing signals from the biasing circuit, and to form first
equipotential lines that are parallel to each other and are perpendicular to the
optical axis. The intermediate electrodes are configured to receive second biasing signals from the biasing circuit, and to form a wide energy barrier. The proximal electrodes are configured to third biasing signals from the biasing circuit, and to form second
equipotential lines that are parallel to each other and are perpendicular to the
optical axis.