A new simple method for analyzing eddy currents caused by magnetic def
lection in an electron optical column is proposed. This method can be
used to calculate the magnetic deflection error caused by eddy current
s by changing the magnetic permeability in the optical column between
zero and normal permeability. These magnetic permeabilities correspond
to the initial and the final states after magnetic deflection. Tile d
eflection error is calculated using the deflection sensitivity and rot
ation seisitivity which is simulated from flux density distribution of
the magnetic deflector. Good agreement was obtained between simulatio
n and experiment.