90 nm resolution reconstruction from a polychromatic signal using monochromatic phase retrieval techniques

Abstract

The use of short wavelength sources for microscopy increases resolution via the diffraction limit, and allows the variation in optical contrast, such as that between carbon and water in the 2-4nm regime, to facilitate useful imaging. However, high material absorption and consequent low phase shift, at such wavelengths limit the availability of focussing optics. For coherent illumination, the electric field just after an object can be reconstructed from its far field diffraction pattern by the process of Coherent Diffractive Imaging (CDI), which solves the well-known phase retrieval problem by iteratively applying constraints in the object and far field (Fourier) planes. Synchrotron sources have achieved 3nm resolution using this technique [1]