Terahertz-Driven Two-Dimensional Mapping for Electron Temporal Profile Measurement

The precise measurement of electron temporal profiles is crucial for advancing electron and X-ray devices used in ultrafast imaging and spectroscopy. While high temporal resolution and a large temporal window can be achieved separately using different technologies, on-the-fly measurement enabling simultaneous high resolution and a large window remains challenging. Here, we present the first terahertz (THz)-driven electron oscilloscope capable of measuring electron pulses with high temporal resolution and a scalable, large temporal window simultaneously. The transient THz electric field induces temporal electron streaking in the vertical axis, while extended interaction along the horizontal axis leads to a propagation-induced time delay, enabling electron beam sampling with a subcycle THz wave. This allows on-the-fly femtosecond electron measurement with a temporal window of tens of picoseconds, surpassing previous THz-based techniques by an order of magnitude. The measurement capability is further enhanced through projection imaging, deflection cavity tilting, and shortened antenna utilization, resulting in signal spatial magnification, extended temporal window, and increased field strength. The technique holds promise for a wide range of applications and opens new opportunities in ultrafast science and accelerator technologies.