Propagation of a Finite Optical Beam in an Inhomogeneous Medium.

by R. F. Lutomirski

Purchase Print Copy

 FormatList Price Price
Add to Cart Paperback45 pages $23.00 $18.40 20% Web Discount

Examination of a diffraction problem, part of a study to determine the effect of atmospheric turbulence on optical and infrared reconnaissance and guidance equipment. After establishing the validity of extending the Huygens-Fresnel principle to refractive media, a formula is derived for the mean spatial intensity distribution in both the Fresnel and Fraunhofer regions from an arbitrary complex disturbance in a finite aperture. The effect of turbulence is shown to enter through the spherical wave modulation transfer function (MTF). Using a modified Kolmogorov spectrum for the index of refraction fluctuations, the formula is used to calculate the mean intensity distribution from a plane wave diffracting from a circular aperture and to give approximate expressions for the beam spreading at various ranges. It is argued that the spherical wave MTF is the basic quantity to be measured for computing the atmospheric degradation of an intensity pattern from an arbitrary disturbance in a finite aperture. 45 pp. Ref. (Author)

This report is part of the RAND Corporation Research memorandum series. The Research Memorandum was a product of the RAND Corporation from 1948 to 1973 that represented working papers meant to report current results of RAND research to appropriate audiences.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.