Patent ID: 7538323

Claim:
An interferometer comprising: a electron source for an electron beam; a condenser lens system for condensing an electron beam emitted from the electron source to a specimen; a specimen holder for holding a specimen irradiated by the electron beam; a lens system for focusing an image of the specimen; a device for observing or recording the specimen; an upper stage biprism comprising one or more electrodes provided on a plane perpendicular to an optical axis and at a position of an image plane of the specimen, the image plane formed on the downstream side of the position of the specimen in the traveling direction of the electron beam on the optical axis; and a lower stage biprism comprising one or more electrodes provided on the downstream side of the position of the upper stage biprism in the traveling direction of the electron beam via one of the lens or the plural lenses of the lens system and on a plane parallel to the upper biprism; wherein each of the two biprisms is capable of moving and rotating the one or more electrodes independently, and applying a voltage independently to deflect an electron beam in one electro-optic plane including the optical axis.