High-Resolution Imaging by Fourier Transform X-ray Holography

TLDR

Fourier transform X‑ray holography can image sub‑micrometer gold structures, achieving resolutions down to 60 nm. Using 3.4‑nm coherent soft X‑ray radiation from beamline X1A, the specimen is positioned near a Fresnel zone‑plate focal spot so that scattered and reference waves interfere to form low‑frequency hologram fringes recorded on a CCD and numerically reconstructed into an image.

Abstract

Fourier transform x-ray holography has been used to image gold test objects with submicrometer structure, resolving features as small as 60 nanometers. The hologram-recording instrument uses coherent 3.4-nanometer radiation from the soft x-ray undulator beamline X1A at the National Synchrotron Light Source. The specimen to be imaged is placed near the first-order focal spot produced by a Fresnel zone plate; the other orders, chiefly the zeroth, illuminate the specimen. The wave scattered by the specimen interferes with the spherical reference wave from the focal spot, forming a hologram with fringes of low spatial frequency. The hologram is recorded in digital form by a charge-coupled device camera, and the specimen image is obtained by numerical reconstruction.