Accession Number : AD0710741

Title :   SELF-DEFOCUSSING 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 self-defocussing 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 self-consistently 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