Surface second-harmonic generation in Si(111) for autocorrelation measurements of 248-nm femtosecond pulses

124-nm radiation by surface second-harmonic generation was used to measure the pulse-width autocorrelation of femtosecond 248-nm pulses. Second-order autocorrelation was obtained for input fluences as high as 0.01 J/cm2. At higher input fluences, autocorrelation of higher order is observed.