Cost-effective technique could shed light on the effects of ultraintense laser pulses in extreme environments

Ultraintense laser pulses enable researchers to investigate the fundamental physics of extreme conditions in strong-field quantum electrodynamics, laboratory astrophysics, and laser nuclear physics. However, determining the real intensity of an ultraintense laser pulse is highly challenging, since regular detectors can’t survive the exposure.

Xu et al. developed an easy-to-implement method that captures the laser intensity distribution on a plane with sub-micrometer resolution.

The method – which only requires an easily obtainable scatter screen and industrial cameras equipped with bandpass filters – uses ultraintense femtosecond laser pulses to irradiate a thin foil. The pulse ionizes the material, accelerating electrons that traverse through the foil and give rise to strong coherent radiation on the other side. Notably, the far field intensity pattern of this radiation strongly correlates with the laser peak intensity and the laser’s focal spot size.

“Current methods have spatial resolutions that are very limited and can only give a volumetrically averaged result,” author Wenjun Ma said. “We believe our diagnostic will be widely adopted rapidly by other high-power laser facilities to assist with experiments.”

While the team experimentally tested the interaction between the ultraintense lasers and thin foils, they theoretically explored the dependence of the far field patterns on the properties of the laser-accelerated relativistic electron sheets. The team also conducted numerical simulations to systematically explore how those patterns change with varying laser peak intensity and focal spot size.

Ma also said that the team’s findings could have a profound impact in relativistic optics. Future work will focus on further developing and enhancing the technique with computational optics and artificial intelligence.

Source: “Diagnosis of focal spots at relativistic intensity utilizing coherent radiation from laser-driven flying electron sheets,” by Shirui Xu, Zhuo Pan, Ying Gao, Jiarui Zhao, Shiyou Chen, Zhusong Mei, Xun Chen, Ziyang Peng, Xuan Liu, Yulan Liang, Tianqi Xu, Tan Song, Qingfan Wu, Yujia Zhang, Zhipeng Liu, Zihao Zhang, Haoran Chen, Qihang Han, Jundong Shen, Chenghao Hua, Kun Zhu, Yanying Zhao, Chen Lin, Xueqing Yan, and Wenjun Ma, Matter and Radiation at Extremes (2025). The article can be accessed at https://doi.org/10.1063/5.0255211 .