The three-dimensional (3D) pupil function for a high-aperture focusing syst
em can be expressed in terms of Hertz or Debye potentials. The electromagne
tic field in the focal region can be calculated directly from these. The De
bye potential pupil function is given for optical systems obeying different
conditions. (C) 1999 Published by Elsevier Science B.V. All rights reserve
d.