Abstract

The design of computer generated diffractive optical elements has traditionally relied upon Fourier optics [1], i.e. the Fresnel or Fraunhofer diffraction theories encompassing the paraxial approximation. Fourier optics, however, is not valid if the surface relief profile contains transverse features that are less than an order of magnitude larger than the incident wavelength. In this regime, non-paraxial theories based on Kirchhoff boundary conditions should be used [2]. Even these theories fail in the resonance domain where, by definition, features of the order of one wavelength are critical [3], and so rigorous electromagnetic theory is required. The fabrication of such resonance domain diffractive optical components is becoming more plausible with the development of microlithographic fabrication technology, which can already achieve sub-micron features with a positional accuracy of about 0.1 µm.

© 1992 Optical Society of America