We present a new technique for measuring the relative delay between a soft x-ray FEL pulse and an optical laser that indicates a sub 25 fs RMS measurement error. An ultra-short x-ray pulse photo-ionizes a semiconductor (Si 3N4) membrane and changes the optical transmission. An optical continuum pulse with a temporally chirped bandwidth spanning 630 nm - 710 nm interacts with the membrane such that the timing of the x-ray pulse can be determined from the onset of the spectral modulation of the transmitted optical pulse. This experiment demonstrates a nearly in situ single-shot measurement of the x-ray pulse arrival time relative to the ultrashort optical pulse.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics