Influence of spatiotemporal coupling distortion on evaluation of pulse-duration-charactrization and focused intensity of ultra-fast and ultra-intensity laser

In a large-scale ultra-fast and ultra-intensity laser system, with the increase of spectral bandwidth beam aperture, spatiotemporal coupling distortion will become more significant. This effect not only degrade quality reduce focusing intensity laser, but also invalidate conventional evaluation method for far-field parameters. A pair beam-expanding lenses, which may bring to an ultrashort pulse, is taken as example. And influence on parameter measurement analyzed in detail. It shows that pulse ordinary lens-pair can peak dramatically, actual duration far field than 10 times longer measured at near by single-shot autocorrelator. this case, estimated using value near-field width be one order magnitude bigger real value. expected results helpful optimal design accurate characterization ultrafast relevant physical experiments.