Non-dispersive charged particle energy analyzer

An electron energy analyzer including a curved electrostatic low-pass reflector and a high-pass electrostatic transmissive filter. The reflector comprises a curved grid, preferably ellipsoidal, and an absorber electrode placed in back of the curved grid with respect to the electron source and biased negatively to the curved grid to act as a reflective low-pass filter and a collimating optics for the reflected beam. The transmissive filter includes first and second flat grids extending across the collimated reflected beam. The second grid on the side of the first grid opposite the curved grid is biased negatively to the first grid and the absorber electrode. A field free region is created by applying the same bias to the curved grid, the first grid, and chamber sidewall sleeve. An electron detector detects all electrons passed by the second grid in an energy band in the overlap of the high-pass and low-pass bands.