Accession Number:

AD0678990

Title:

OPTICAL PROPAGATION IN A WEAKLY INHOMOGENEOUS MEDIUM,

Descriptive Note:

Corporate Author:

RAND CORP SANTA MONICA CALIF

Personal Author(s):

Report Date:

1968-11-01

Pagination or Media Count:

39.0

Abstract:

A self-consistent Greens function technique is used to obtain the electromagnetic field and its corresponding intensity to second order in the index of refraction fluctuations. The qualitative results of the analysis are for propagation distances R less than a critical range Rc, the perturbation method gives valid results. For R Rc the field is primarily coherent since the fluctuations in the field are small. It is demonstrated that the solution obtained for the field conserves energy. Physically, the energy removed from the average field is transferred to the random fluctuating part of the field. A solution is found for the second Rytov approximation which is correct through terms second order in the n1, where n1 is the fluctuating part of the index of refraction. With this solution a condition of validity on the Rytov approximation is obtained. It is concluded that the Rytov and Born approximations have the same domain of validity -- both valid only for R Rc. For R Rc the perturbative method breaks down the field is essentially incoherent since the coherent part of the field is exponentially small. For these range values a statistical argument is given to obtain intensity statistics, and an approximate expression valid for all values of R is derived for the intensity statistics and compared with experiment. It is found that the agreement is good. Author

Subject Categories:

  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE