Patent ID: 7923685

Claim:
An electron beam device comprising, an electron beam source, a condenser optical system for irradiating an electron beam emitted from the source onto a specimen, a specimen holder for holding the specimen irradiated with the electron beam, and an imaging lens system for imaging the specimen, wherein a first electron biprism is disposed downstream of the condenser optical system in a traveling direction of the electron beam on an optical axis of the electron beam device and upstream of a position at which the specimen is disposed in the traveling direction of the electron beam and a second electron biprism is disposed downstream of the first electron biprism in the traveling direction of the electron beam via the specimen and one or a plurality of lenses of the imaging lens system, wherein the device comprises an electron optical system in which in a first electromagnetic lens located downstream of the first electron biprism in the traveling direction of the electron beam, an image of the first electron biprism is formed in a magnetic field of the first electromagnetic lens by one or a plurality of times, an image thereof is also formed on an object plane of second electromagnetic lenses and thereafter downstream of the first electromagnetic lens in the traveling direction of the electron beam, and the image forming actions are obtained in subsequent downstream lens systems, and wherein a position of the specimen along an axis of the electron beam is identical to one image plane or one of plural image planes on each of which the image of the first electron biprism is formed.