aperturgitter

Aperturgitter, or aperture grid, is a thin, conducting grid that contains a regular pattern of openings. It is used to transmit, gate, or shape beams of charged particles or electromagnetic radiation while providing electrical shielding and a defined boundary.

Construction and principles: An aperture grid is typically made from metal foils or meshes such as stainless steel or tungsten, or from microfabricated structures. The openings are usually circular or square, with a defined pitch and opening diameter that determine the transmitted beam geometry. Grids are often mounted in vacuum-compatible frames and may be connected to electrical supplies. By applying voltages to the grid or nearby electrodes, electrostatic fields can be established to focus, deflect, attenuate, or gate the beam, while the grid simultaneously acts as a boundary and shield against stray particles or light.

Applications: Aperture grids are used in various instruments to control beams of charged particles or radiation. In electron optics (scanning and transmission electron microscopes), they shape and limit the electron beam. In mass spectrometry and ion optics, they function as gates or shutters to regulate ion transmission. They also appear in X-ray and neutron instrumentation and in other vacuum-based devices where precise beam control and shielding are required. The exact geometry, material choice, and operating voltages depend on the specific application and instrument design.

See also: aperture mask, beam shaping, electrostatic lens, grid electrode.

Notes: The term is used across multiple disciplines, and the exact meaning can vary with context.