Patent ID: 8704536

Claim:
An electron microscope stage assembly comprising: a first moving capacitor plate and a second moving capacitor plate disposed symmetrically about a first axis, the first and second moving capacitor plates attached to a moving portion of the stage assembly, the stage assembly being coupled to an electron microscope stage; four or more stationary capacitor plates, opposed to the first and second moving capacitor plates, the four or more stationary capacitor plates disposed symmetrically about a second axis, the four or more stationary capacitor plates attached to a stationary portion of the stage assembly; a measuring circuit configured to measure capacitances between the first moving capacitor plate and the four or more stationary capacitor plates, and configured to measure capacitances between the second moving capacitor plate and the four or more stationary capacitor plates; and a calculating circuit configured to receive the measured capacitances from the measuring circuit and configured to calculate displacement of the moving portion relative to the stationary portion.