  Knowledge of spatio-temporal couplings such as pulse-front tilt or curvature
is important to determine the focused intensity of high-power lasers. Common
techniques to diagnose these couplings are either qualitative or require
hundreds of measurements. Here we present both a new algorithm for retrieving
spatio-temporal couplings, as well as novel experimental implementations. Our
method is based on the expression of the spatio-spectral phase in terms of a
Zernike-Taylor basis, allowing us to directly quantify the coefficients for
common spatio-temporal couplings. We take advantage of this method to perform
quantitative measurements using a simple experimental setup, consisting of
different bandpass filters in front of a Shack-Hartmann wavefront sensor. This
fast acquisition of laser couplings using narrowband filters, abbreviated
FALCON, is easy and cheap to implement in existing facilities. To this end, we
present a measurement of spatio-temporal couplings at the ATLAS-3000 petawatt
laser using our technique.
