Experimental 3D coherent diffractive imaging from photon-sparse random projections.

Area of Science:

• Physics
• Materials Science
• Structural Biology

Background:

• Atomic resolution structure determination is vital for understanding structure-function relationships.
• X-ray free-electron lasers (XFELs) enable imaging of nanoscale particles using coherent diffractive imaging.
• Signal sparsity, where photon counts are lower than detector pixels, hinders atomic-scale imaging.

Purpose of the Study:

• To address the challenge of signal sparsity in X-ray imaging for atomic resolution.
• To demonstrate the feasibility of overcoming low photon counts in single-particle imaging.
• To provide an experimental validation for XFEL-based single-particle imaging.

Main Methods:

• An experimental analog using a conventional X-ray source was developed.
• Coherent diffractive imaging was employed to reconstruct particle structures.
• Photon-sparse random projections were utilized to simulate XFEL conditions.

Main Results:

• The analog experiment achieved signal levels comparable to XFEL experiments on single biomolecules.
• The study demonstrated that a sparsity of 1.3 × 10^-3 photons per pixel per frame can be overcome.
• 3D coherent diffractive imaging was successfully performed from photon-sparse random projections.

Conclusions:

• The experimental analog provides a crucial cross-check for data fidelity in XFEL experiments.
• Overcoming signal sparsity is key to achieving atomic resolution in XFEL single-particle imaging.
• This work offers vital insights and experimental validation for advancing XFEL-based structural analysis.