A general technique for measuring the electric field vector of the ultrashort pulses from mode locked laser systems is described. The technique is applied to perhaps the most difficult laser to analyze, the dye mode locked, Nd³⁺:glass laser whose pulses change rapidly in bandwidth and amplitude, are chirped, and can occur in quite short pulse trains. The results of these measurements indicate a rather rapid change in the phases between modes and a plot of the phase change as a function of mode frequency has been obtained.