High-energy pulsed laser interaction with metallic surfaces

Some properties of laser material interactions in vacuum were investigated during intense laser irradiation by a Q switched ruby laser pulse of 20 nsec FWHM and 0.61 output power. Reflectance (total, spectral and probe laser), spectroscopic analysis and microstructural observations were examined. Primarily Cu, Sn, Zn, Bi, Al, Fe and Si samples were investigated. The intensities of incident laser on the target were in the range of 10 to the 7th power - 10 to the 9th power w/cu cm. In both total and specular reflectance measurements the reflected light signal from the target and a sample signal of incident laser pulse were detected by a single detector system with a rise time 1 nsec. An integrating sphere was used for the total reflectance measurement. An interference filter at the ruby laser wavelength was used in front of the detector to remove the observed 'light flash' from a plasma created at or in front of the target surface. The original input pulses reflected from the target into the integrating sphere were recovered from the output pulses leaving the sphere using an impulse response method. The recovered reflected and the sample pulses were then used to determine the time resolved total reflectance curves.