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.

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.