Full field tabletop EUV coherent diffractive imaging in a transmission geometry.

Area of Science:

• Optics and Photonics
• Microscopy
• Materials Science

Background:

• Coherent diffractive imaging (CDI) enables high-resolution microscopy but often requires complex setups.
• Existing EUV microscopy methods face limitations in efficiency and sample illumination uniformity.
• Imaging extended, non-periodic objects at the nanoscale presents significant challenges.

Purpose of the Study:

• To demonstrate the first general tabletop extreme ultraviolet (EUV) coherent microscope.
• To image extended, non-isolated, and non-periodic objects with high fidelity.
• To enable quantitative thickness measurements of semi-transparent samples.

Main Methods:

• Implementation of keyhole coherent diffractive imaging (CDI) using curved mirrors.
• Utilization of a tabletop high harmonic generation (HHG) source for EUV illumination.
• Employing the unscattered light from the sample as a holographic reference wave.

Main Results:

• Achieved improved imaging system efficiency and uniform sample illumination compared to Fresnel zone plates.
• Successfully retrieved quantitative thickness information from semi-transparent samples.
• Demonstrated excellent tabletop image fidelity comparable to, and in some cases superior to, scanning electron and atomic force microscopy.

Conclusions:

• The developed tabletop EUV coherent microscope is a versatile tool for nanoscale imaging of complex objects.
• The integration of keyhole CDI with curved mirrors and HHG sources offers a practical and efficient imaging solution.
• This technique provides a pathway for quantitative nanoscale metrology in various scientific fields.