Measurement of femtosecond laser focusing spot by optical imaging and pinhole method

For the interaction experiments between ultra-intense laser and targets, characterizing the laser focusing spot is very important. Two different methods were adopted on SILEX-Ⅰ Ti:sappire femtosecond laser system. One is directly imaging the laser spot on 16bit CCD, another is measuring the transmitting energy behind a pinhole which was exactly positioned on the laser focusing spot. Both methods can give the correct distribution of the focal spot with less than error 10%.