GRENOUILLE measures spatio-temporal distortions!
Sending a pulse with spatial chirp into a GRENOUILLE yields a tilted trace. Because GRENOUILLE traces use the SHG optical nonlinearity, which yields symmetrical traces, any tilt in the trace is an excellent indicator of spatial chirp.
Sending a pulse with pulse-front tilt into a GRENOUILLE yields a trace displaced along the delay axis. Because GRENOUILLE traces are ordinarily centered on the delay axis, any displacement in the trace is an excellent indicator of pulse-front tilt.
Experiments nicely confirm these nice features of GRENOUILLE. Read our papers on GRENOUILLE and spatial chirp and pulse-front tilt.
There are eight first-order spatio-temporal distortions, but only two are independent. Because GRENOUILLE measures two of them, it also yields the other six as well. The others include angular dispersion, the ultrafast lighthouse effect, wave-front rotation, etc.