Krypton fluoride laser pulse shortening by stimulated thermal scattering on a liquid surface.
Pulse shortening of the backscatter of a KrF excimer laser beam focused on the surface of n-hexane is reported. Simultaneous measurements of the backscattered beam, a Fresnel reflected beam, incoherent scattered photons from a liquid surface, and a transmitted beam are performed. The results show that the surface reflected beam disappears followed by beam expansion and the transmitted beam is reduced to form a filamentlike structure with the onset of backscatter. The pulse width of the backscattered beam shows a clear dependence on the focal position in the liquid. Incoherent scattering is sharply enhanced when the laser beam is focused at the liquid surface where the backscattered beam is especially short. The observed phenomena indicate that stimulated thermal scattering is the pulse shortening mechanism.
Shortening of KrF(*) laser pulses using stimulated Brillouin scattering.
Pulses as short as 43 psec were generated by Brillouin backscattering at 248 nm in cyclohexane. The measurements show that the process is accompanied by considerable spectral broadening of the reflected radiation.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.