Temporal characterization of the Stanford mid-IR FEL micropulses by “FROG”

We present the results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL. FROG is a recently developed method to acquire complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. Experimental examples of near-transform-limit, chirped, and atmospheric absorption perturbed pulses are discussed.