Abstract

Ultrashort x-ray pulses are powerful diagnostic tools, combining the temporal resolution typically reserved for optical (laser) pulses with atomic scale spatial resolution that, in principle, can be achieved with use of high energy electromagnetic radiation. Progress in the development of femtosecond x-ray sources has been hindered by an inability to measure x-ray pulses of femtosecond duration. Streak cameras typically are used to measure ultrashort x-ray pulses, however the ~1 ps resolution limit of these instruments abates their usefulness in the femtosecond regime. We report demonstration of a visible/x-ray cross-correlation technique based on laser-assisted x-ray photoionization which has been used to measure 50-fs soft x-ray pulses. The technique is widely applicable to soft and hard x-rays and permits the first direct measurements on the duration of femtosecond high order harmonic radiation.

© 1996 Optical Society of America