Accession Number:

AD0603026

Title:

PLANE WAVE DIFFRACTION BY THICK DIELECTRIC GRATINGS, AND ZONE PHASE PLATES.

Descriptive Note:

Technical rept. no. 77,

Corporate Author:

ILLINOIS UNIV URBANA ENGINEERING EXPERIMENT STATION

Personal Author(s):

Report Date:

1964-06-01

Pagination or Media Count:

149.0

Abstract:

The diffraction of a plane electromagnetic wave by an infinite grating of dielectric bars was obtained by two methods. One is an improved wave optics method, accounting for multiple reflections. The other is a more exact formulation as a boundary value problem, which is solved numerically. The results were compared with each other and with experiment. The diffraction is specified in terms of the amplitudes of the grating lobes, both the real classical lobes, and the lobes with complex directions, corresponding to waves evanescent in the direction normal to the grating. The latter are found to be relatively negligible, as compared to those for a grating of perfect conducting bars, for example. This important result is discussed at length. Though the more exact analysis appears to work at least for grating constants of between zero and five wavelengths, the emphasis is placed on results for grating constants somewhat larger than a wavelength. These are used to make inferences about the action of zone phase plates, used as focussing devices, by considering the plates as generalized gratings and applying parageometric optics methods. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE