Abstract: The phase spectrum of an ultrashort pulse is measured based on two-dimensional spectral shearing interferometry with zero delay. The measurement is performed utilizing an optical source pulse from which is extracted a short pulse and from which a chirped component is generated. The chirped component is split into first and second chirped pulses. The first and second pulses are then mixed with the short pulse in a nonlinear medium to produce up-converted and spectrally sheared copies of the first and second chirped pulses, which are measured in a spectrometer. A plurality of path lengths for the first second chirped pulses is provide to generate delays and shift the relative positions of the first and second chirped pulses for additional measurements. The apparatus and methods are uniquely suited for characterizing single-cycle pulses.