Patent ID: 7141790

Claim:
A positron beam apparatus comprising: an electron source; a positron beam source; a sample stage for mounting a sample; electron beam irradiation system for focusing an electron beam emitted from said electron source and irradiating the focused electron beam onto said sample; an electron beam position controlling system for controlling irradiating position of electron beam on said sample; positron beam irradiation system for irradiating positron beam on said sample; a detector for detecting electromagnetic waves generated from said sample by irradiation of said electron beam and positron beam; a controller for synchronizing information of irradiating position of said electron beam and output signals of said detector to generate an image signal; means for displaying said image signal, wherein said positron beam sources comprises a plurality of positron sources; a shield with a window, through which positron beams pass, placed between said sample stage and said plurality of positron sources; and means for moving one positron source out of said plurality of positron sources to a position where emitted positrons pass through said window part, wherein said plurality of positron sources have different nuclides from each other.