Two-color subpicosecond optical sampling technique.

We have constructed a laser system for performing pump-probe experiments with independently tunable pump and probe pulses. The cross correlation between the two pulses, which determines the resolution of the system, is measured to be 150 fs. This system uses two regeneratively mode-locked Ti:sapphire lasers with slightly different repetition rates and automatically scans the time delay between the pump and probe lasers 80 times per second.