FABRICATION OF A MICROENGINEERED QUADRUPOLE ELECTROSTATIC LENS

A self-aligning method of mounting Four parallel cylindrical electrode rods in the geometry of a miniature quadrupole electrostatic lens is described. Pairs of electrode rods are mounted in V-grooves, which are fabricated by anisotropic etching of Si wafers. Two etched dies, sepa rated by further insulating cylindrical spacer rods, comprise a comple te lens assembly. For prototype lenses with 500 mu m electrode diamete r, electrode spacings were maintained to within 3% of their design val ue, suggesting that this method of construction Will allow sufficient precision for such lenses to act as mass analysers in miniaturised qua drupole mass spectrometers.