Extended Data Fig. 5: Experimental setup of echelon-based single-shot measurement.

a, A 2D schematic of the experimental setup. Abbreviations describing the setup are listed in the upper-right corner. Time delay is spatially imprinted on the probe laser by an echelon mirror; this imprinting converts a probe pulse to beamlets. Notably, each delay corresponds to the double length of the step height of the echelon mirror, as shown in the magnified images around the mirror in the black dashed rectangle. Red solid and dashed arrows denote the path of the probe laser before and after the reflection, respectively. The CL1 focuses the parallel beamlets into a line in the x-direction on the ZnTe, and the CL2 makes them parallel again. The distance between the CL1 and the echelon mirror is its focal length to suppress the divergence due to the step-like mirror surface. The CL3 is rotated 90° with respect to the CL1 and CL2 for imaging in the y-direction. Here, the magnifications in the x- and y-directions are 2.8 and 1.0 on the CCD camera, respectively. The relative angle between the Pol1 and Pol2 is 90°. We used the phase offset method by rotating the QWP. The incidence angle of the probe laser into the ZnTe was 25°, whereas the electron beam path was perpendicular. b, A 3D schematic around the ZnTe crystal before the electron beam hits the crystal. The PL is linearly focused on the crystal by the cylindrical lens. The polarization of the PL and the measured electric field are directed in the x-direction, which corresponds to the [-110] crystal axis.