unipotential electrostatic lens

unipotential electrostatic lens

[¦yü·nə·pə′ten·chəl i¦lek·trə¦stad·ik ′lenz]
(electronics)
An electrostatic lens in which the focusing is produced by application of a single potential difference; in its simplest form it consists of three apertures of which the outer two are at a common potential, and the central aperture is at a different, generally lower, potential.