
Accession Number : AD0710741
Title : SELFDEFOCUSSING OF A LIGHT BEAM: EXAMINATION OF A COMPUTATIONAL SCHEME.
Descriptive Note : Memorandum rept.,
Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C
Personal Author(s) : Rosenstock,Herbert B. ; Hancock,J. Harrison
Report Date : JUL 1970
Pagination or Media Count : 12
Abstract : A frequently used iterative scheme for computing selfdefocussing of a light beam is examined critically. The phenomenon in question is the heating of a fluid by a light beam traversing it, thus producing a change in the index of refraction and deflection of the beam from the course it would take in vacuo. The iterative method utilizes the undeflected beam, rather than selfconsistently the final resulting beam, to calculate the heating. A simple physical situation amenable to both exact solution and to several steps in the iterative scheme enables us to study the validity of the latter. It is found that the first step in the iteration, which is often the only one that can be taken, gives wholly incorrect results; indeed, the very convergence of the scheme is in doubt, in the sense that even a large number of steps give results that at large enough range differ by an arbitrarily large amount from the correct ones. (Author)
Descriptors : (*LIGHT, FOCUSING), (*LIGHT TRANSMISSION, GASES), FLUIDS, HEATING, REFRACTIVE INDEX, DEFLECTION, MATHEMATICAL MODELS
Subject Categories : Optics
Distribution Statement : APPROVED FOR PUBLIC RELEASE