Real time femtosecond optical pulse measurement using a video-rate frequency-resolved optical gating system

Abstract
We describe an improved instrument for measuring at video rate (30 frames per second) the second-harmonic frequency-resolved optical gating trace of femtosecond pulses from a mode-locked laser oscillator. The system comprises separate scanning acquisition and pulse retrieval elements which together enable the exact pulse profile to be viewed in real time with a typical refresh rate of 1 Hz. Details are given of the optical system used, the electronic synchronization circuits and the acquisition and retrieval software employed.