Energy-yield and conversion-efficiency measurements of high-order harmonic radiation

Experimental measurements of the absolute energy yields and conversion efficiencies of high-order harmonic radiation in the spectral range of 31 to 17 nm are presented. We examine energy yields as a function of a number of parameters including drive laser wavelength, target atom, focal geometry, and peak laser intensity, and we have generated individual harmonics with energies as high as 60 nJ at wavelengths as short as 20 nm. Under optimum conditions, we find that conversion efficiencies of as high as ${10}^{\mathrm{-}7}$ into each harmonic are possible.