Propagation of High-Energy 10.6-Micron Laser Beams Tthrough the Atmosphere
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
The purpose of the present investigation is the determination of the properties of an intense 10.6-micron laser beam propagating through the open atmosphere in the presence of wind or slewing, or both. It is shown that the Maxwell equations can, in this problem, be reduced to the study of the scalar wave equation with a varying index of refraction. The index of refraction is related to the atmospheric density therefore, the density changes in the air due to beam absorption are related to the absorption coefficient of the air and to the intensity of the beam, using the linearized hydrodynamic equations. A detailed discussion of the mechanisms of photon absorption by the constituents of the air is presented. The resultant equation for the scalar wave is a nonlinear partial differential integral equation which is solved numerically. The algorithm used for the computer code is discussed, together with criteria that have been determined to be useful in assessing the accuracy and reliability of the numerical results. The solutions of several different problems are presented and discussed. In particular, it is found that a beam quality is degraded for water vapor pressures at or near sea level, and b beam slewing reduces the detrimental effect of water vapor.
- Atmospheric Physics
- Lasers and Masers
- Radiofrequency Wave Propagation