Electrostatic particle beam deflector

An electrostatic deflector for a particle beam apparatus comprises opposing deflector plates that face one another across a particle beam gap and are electrostatically chargeable. Each deflector plate comprises its own voltage driver, which has a DAC and amplifier. Digital electronics receives an input digital code that expresses the complementary voltages to be applied to opposing deflector plates. When the input digital code is determined to provide a non-linear output response voltage from a DAC, the digital electronics provides an output digital code with a different digital code that provides a linear response from the DAC while providing the same differential voltage between the first and second deflector plates.