The Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) has proposed a new scheme for single-shot ultrafast multimodal coherent diffraction imaging, which realizes ultrafast time-resolved real-time phase imaging.

The scheme is based on the principle of dynamic range multiplexing of detector, which breaks through the technical difficulties of achieving high temporal resolution, spatial resolution and signal-to-noise ratio at the same time in single-shot ultrafast phase imaging. Moreover, by choosing the probe pulse width and adjusting the pulse sequence time delay, the method can achieve picosecond or even femtosecond temporal resolution and an ultra-wide imaging time range (on the order of femtoseconds to microseconds). The related research results were published in Photonics Research under the title of "Single-shot ultrafast multiplexed coherent diffraction imaging" on July 27, 2022.

Ultrafast time-resolved real-time phase imaging has important applications in shock wave propagation, laser-induced damage, and exciton diffusion, especially for ultrafast transient phenomena that are not repeatable or difficult to generate. Ultrafast time-resolved imaging applications often require high temporal resolution, spatial resolution, frame rate, and signal-to-noise ratio, but current ultrafast phase imaging technologies cannot simultaneously achieve the above requirements.

To address this challenge, the researchers propose a single-shot ultrafast multiplexed coherent diffraction imaging (SUM-CDI) method. The single-shot ultrafast phase imaging was successfully achieved by using the multiplexed phase retrieval algorithm and the beam-splitting encoding averaging technique, which can achieve high spatial and temporal resolution and signal-to-noise ratio.

Using this SUM-CDI technique, the physical process of UV laser-induced surface damage and internal filamentation of K9 glass was experimentally measured. The transient changes of internal filamentation, surface damage, shock wave and other processes are studied and the feasibility of this technique for nanosecond time-resolved phase imaging is verified. The spatial resolution reaches 6.96μm; compared with single mode, the phase measurement error is less than 1%.

Therefore, this method has important application prospects in real-time ultrafast measurement, especially in the ultrafast field that requires phase measurement.