Spectrometer objective for particle beam measuring instruments

US4812651A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Hans-Peter Feuerbaum · Hersbruck, DE
• Juergen Frosien · Ottobrunn, DE

Key dates

• Filing date: Nov 13, 1987
• Grant date: Mar 14, 1989
• Expiry date: Nov 13, 2007

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J2237/24585
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A spectrometer objective includes a generally asymmetrical objective lens having a short focal length, a deflection system disposed within the objective lens symmetrically relative to an optical axis, and an electrostatic retarding field spectrometer including an electrode arrangement for accelerating the secondary electrons generated on the specimen. The electrode arrangement of the retarding field spectrometer includes an electrode pair for establishing a spherically symmetrical retarding field. The electrode arrangement for extracting and accelerating the secondary particles includes a grid electrode disposed in a region of the lower pole piece of the objective lens and of a planar electrode disposed in the particle beam path immediately above the specimen, wherein the planar electrode is charged with a potential lying between the potential of the specimen and the potential of the grid electrode.