Electron beam device

Claim 1

In an electron microscope or the like having an electron optical axis, an apparatus for deflecting an electron beam to irradiate a location on a specimen at different easily selectable azimuthal angles of incidence comprising: A. a deflection stage being equipped with deflecting coils L1x and L1y for generating magnetic fields substantially at right angles to each other and perpendicular to the optical axis; B. a second deflection stage being equipped with deflecting coils L2x and L2y for generating magnetic fields substantially at right angles to each other and perpendicular to the optical axis, said magnetic deflecting fields of said second stage being substantially aligned with the magnetic deflecting fields of the first stage; C. a deflecting current supply for supplying individual coil currents I1x, I1y, I2x and I2y to each of said deflecting coils L1x, L1y, L2x and L2y respectively, said individual coil currents being the total of a plurality of individually variable analog currents, such that I1x i1x1 + i1x2 + i1x3 I1y i1y1 + i1y2 + i1y3 I2x i2x1 + i2x2 I2y i2y1 + i2y2 means for varying simultaneously and proportionally at least some of the analog currents controlling coil current to both first and second stages, such that the means for controlling i1, i2x1 and i1y2 are interconnected and means for controlling i1y1, i2y1 and i1x2 are interconnected, such that the one deflection stage redirects the electron beam deflected by the other stage to the location on the specimen thus changing the azimuth angle of incidence without moving the location on the specimen on which the beam is incident notwithstanding slight misalignment of the deflection stages and slight deviation from right angles between the fields of the separate stages.