Berkeley Lab

Laser Plasma Microsource Enables Bi-Modal Imaging

An international team, including ATAP scientists Tobias Ostermayr of the Berkeley Lab Laser Accelerator Center and Axel Huebl of the Accelerator Modeling Program, has made the first proof-of-principle demonstration of bi-modal radiographic imaging for biological and technological objects with a laser-driven microsource of x rays and protons. The results were announced December 2 in the journal Nature Communications.

Tobias Ostermayr


Axel Huebl


Ostermayr is lead author of the paper and (together with co-corresponding author Joerg Schreiber of Ludwig-Maximilians-Universität München and Max-Planck-Institut für Quantenoptik) originated the idea. Huebl performed particle-in-cell simulations in support of the study. The experiments were performed with the Texas Petawatt laser at the University of Texas at Austin.

Synchronized single-sourcing of multiple modalities
Conventional radiography machines produce only a single kind of radiation, such as protons, electrons, or x-rays. Using more than one kind of radiation source gives complementary sets of information about the specimen, but in order to take advantage of this, significant post-processing is usually needed because the sources and image acquisitions were separate in space and/or time.

Laser-driven plasmas can simultaneously emit multiple forms of radiation, including x-rays and protons, and they produce it in short bursts, which is also desirable for, say, “freezing” motion. This study demonstrated, for the first time ever, how such a laser-driven source can be used to make images of biological and technological samples.

Bimodal imaging concept

In this conceptual illustration, a test object (a cricket) casts shadows in a proton beam (green) and an x-ray beam (blue) to record radiographic images with both beams in a single laser shot. The proton image is color coded in blue and red, immediately downstream of the test object; the x-ray image is the grayscale plane at far right. The images show actual experimental data. The laser plasma provides a single source of protons and x-rays, intrinsically synchronized on the nanosecond scale and originating (within µm) from the same spot, as compared to existing, separate sources of these two imaging modalities. Illustration by Tobias Ostermayr, Berkeley Lab.

The team achieved intrinsic nanosecond-scale synchronization of these two powerful and important imaging techniques (compared to seconds or minutes in conventional machines), and the two radiation sources overlapped on a scale of a few micrometers. These attributes, combined with the exquisitely small source size enabled by laser plasma techniques, gave sharper and more detailed insights into materials and samples than could be expected from either source alone—a unique capability of laser plasmas.

In the near future, the researchers hope to extend multimodal imaging capabilities and applications to include electrons and neutrons, and to image dynamic events.

To learn more…
T.M. Ostermayr et al., “Laser-driven x-ray and proton micro-source and application to simultaneous single-shot bi-modal radiographic imaging,” Nature Communications 11, 6174 (02 December 2020).

“A new laser-driven X-ray and proton micro-source,” Attoworld, 3 December 2020.