Differential near-edge coherent diffractive imaging using a femtosecond high-harmonic XUV light source

Area of Science:

• Atomic, Molecular, and Optical Physics
• Materials Science
• Nanotechnology

Background:

• Coherent diffractive imaging (CDI) enables high-resolution imaging without lenses.
• Achieving element-specific contrast in CDI, especially in tabletop setups, remains a challenge.
• Ultrafast extreme ultraviolet (XUV) light sources offer new possibilities for dynamic imaging.

Purpose of the Study:

• To demonstrate element-specific contrast enhancement in tabletop CDI.
• To improve chemical sensitivity and image reconstruction quality in ultrafast imaging.
• To utilize the tunable photon energy of XUV sources for contrast manipulation.

Main Methods:

• Employed an ultrafast XUV light source with tunable photon energy.
• Combined diffraction measurements below and above the Aluminum L(2,3) absorption edge.
• Utilized differential imaging to isolate element-specific information.

Main Results:

• Successfully retrieved the spatial autocorrelation function of a double pinhole in aluminum foil.
• Observed significant fringe visibility changes (0 to 0.53 ± 0.06) across the absorption edge.
• Achieved a differential image fringe visibility of 0.73 ± 0.08, demonstrating enhanced contrast.

Conclusions:

• Variations in XUV optical constants near inner-shell absorption edges can be exploited for element-specific contrast.
• This technique enhances chemical sensitivity in laboratory-based ultrafast imaging.
• The proof-of-principle experiment validates the potential of this approach for advanced materials characterization.