January 1, 2007 Version 7 of VideoFROG has just been released. With a new look and user interface, pulse measurement has never been easier.
Not only is VideoFROG fast--it easily tracked phase changes from a Dazzler in demonstrations in France, it is accurate too. The following plots show data taken using VideoFROG. I used a pulse shaper (zero-dispersion stretcher-compressor with an LCD spatial light modulator) and home-built GRENOUILLE to measure changes in the spectral phase of an ultrashort laser pulse induced by the pulse shaper.
Shown above are the results from 12 different measurements of 12 different amounts of linear chirp (quadratic spectral phase). An equal amount of linear chirp is added to each measurement. The amount of chirp varies from transform limited to modest amounts of spectral chirp. VideoFROG was only allowed to settle for the time it took to notice the phase change and save the data (~ 1 sec).
Shown above is a plot comparing the calculated difference between each phase measurement and the measured difference. Where the intensity is highest, the phase accuracy is better than 0.01 radians while the precision is ~0.02 radians or better. In the wings, where the intensity is nearly zero, the phase accuracy is ~0.05 radians while the precision is ~ 0.1 radians. Only an interferometer can do better!
Real-time FROG. It is here. It is fast. It is accurate and precise!
