Patent ID: 8013298

Claim:
An electrostatic electron spectrometry apparatus, comprising: a spectrometer that includes, a first deflection plate having a convex surface with a first radius of curvature; a second deflection plate having a concave surface with a second radius of curvature larger than said first radius of curvature, said convex surface facing but spaced from said concave surface to define a curved space for passage of scattered electrons, said curved space having an electron entrance and an electron exit; a first biasing source coupled to said first deflection plate to bias said first deflection plate to a first voltage; and a second biasing source coupled to said second deflection plate to bias said second deflection plate to a second voltage, said second voltage being different from said first voltage to generate electric field lines inside said curved space; wherein said spectrometer is configured so that said scattered electrons enter said curved space through said electron entrance along any trajectory residing in a predefined angular spread, are focused once at a first point inside said curved spaced, and focused subsequently at a second point outside said electron exit.