Microbeam probe apparatus

Claim 1

A microbeam probe apparatus comprising an ion or an electron particle source (10) for producing an essentially collimated primary beam (12) of charged particles having a relatively high energy, a charged particle objective system including first and second sets of electrodes (26, 24-24, 22) to produce first and second electrostatic lens fields of short focal lengths in first and second areas of space respectively, said fields being positioned to be transversed by the path of said primary beam 12 in the order named, a diaphragm (32) having a fine aperture (34) positioned between said first and second areas of space, a conductive surface (16) comprising a sample area to be investigated positioned in spaced relationship near said second set of electrodes on the side thereof, remote from said first set, means for biasing said electrodes of said first and second sets, and said conductive surface to a. produce first and second electrostatic lens fields which cooperate to focus said primary beam through said aperture (34) into a small spot on said sample area, b. cause secondary charged particles, which emerge from said sample area under the action of said primary beam to accelerate towards said second set of electrodes, and be focused by said second lens field into a focus area within said aperture (34), c. and collimate said secondary particles passing through said opening into a secondary beam (40) of relatively low energy traveling in a direction essentially opposite to that of said primary beam (12), and deflecting means (62) acting on said primary and secondary beams to deflect said relatively low energy secondary beam (40) away from the path of said primary beam while leaving said relatively high energy primary beam essentially unaffected.