Spatio-spectral characterization of ultrashort laser pulses with a birefringent delay line

We utilize a birefringent delay line to perform spatially-resolved Fourier transform spectroscopy at multiple planes around the focus of an ultrashort laser pulse. Combining these measurements at multiple planes with phase-retrieval, i.e. the INSIGHT technique, allows for the determination of the three-dimensional laser field, in both amplitude and phase, lacking only the knowledge of a spatially-uniform spectral phase. We use the device to simultaneously measure two low-order spatio-temporal couplings resulting from a misaligned chromatic lens doublet. Besides being a new implementation of spatio-spectral characterization of ultrashort pulses, this technique allows for more accuracy and stability in spatio-spectral characterization and a push to shorter wavelengths, and may ultimately enable sparse measurements. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement