Patent ID: 9153412
Filing Date: 2015-10-06
Classification: G01N,H01J

Abstract:
1. A device for imparting an orbital angular momentum to a charged particle wave propagating along an axis in a charged particle beam generating apparatus, the device comprising a first conductive element comprising a plurality of angularly spaced electrical conductors arranged around the axis; a second conductive element, in which said first conductive element and said second conductive element are spaced apart along the direction of said axis, and in which said first conductive element and said second conductive element are configured to transmit a charged particle wave propagating along said axis; and a voltage terminal configured to receive an externally supplied voltage, a ground terminal, and a plurality of resistive elements connected in series between said voltage terminal and said ground terminal to form a voltage ladder, wherein each angularly spaced electrical conductor is connected to a corresponding rung of said voltage ladder such that each angularly spaced electrical conductor receives a voltage greater than a previous angularly spaced electrical conductor in an angularly progressive series around said axis, wherein each angularly spaced electrical conductor acts as an electrostatic lens in combination with the second conductive element when a reference voltage is applied to the second conductive element, such as to provide an angular gradient of electrical potential difference around said axis to induce an angular gradient of the phase of the charged particle wave.