Abstract: The indicial equation of the equipotential lines of two superimposed electrostatic fields has a similar form to that of the moire fringes formed by two overlapped gratings. So, the corresponding gratings can be designed to visualize a given electrostatic field, and thus to help students in their understanding of fields. This method is also helpful to electric field analysis. Both theoretical analysis and specific examples are given in this paper.

Key words: information optics, electromagnetics, moir~ fringes, electrostatic field, equipotential lines