Laser Interaction with Metallic Surfaces.
Final technical rept. 1 Sep 78-31 Aug 81,
POLYTECHNIC INST OF NEW YORK FARMINGDALE MICROWAVE RESEARCH INST
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Direct real-time measurements of a target materials optical properties with subnanosecond resolution may provide crucial, process-revealing signatures in following the interaction of an intense laser beam with a metal as the surface progressively undergoes heating, plastic deformation, slip, vaporization, ejection of liquid metal, plasma formation, etc. Three classes of physical processes have been proposed to account for a substantial decrease in reflectance observed during the interaction of an intense laser pulse with a metal surface 1 deformation of the surface, 2 plasma formation, and 3 a nonlinear process causing enhanced absorption within the metal. Thus far we may conclude that specular reflectance is a sensitive indicator of surface deformation. Total reflectance measurements, on the other hand, indicate that until the surface temperature of a metal target reaches the vicinity of the boiling point, the total reflectance does not differ significantly from that given by a Drude-type free-electron model. The reflectivity decrease of a Drude model for a metal heated from room temperature to a liquid at the boiling point is not large enough to account for the substantial reflectance decrease observed experimentally. Author
- Lasers and Masers
- Properties of Metals and Alloys
- Atomic and Molecular Physics and Spectroscopy