CDI: Coherent Diffraction Imaging

Resolution beyond the limitations given by X-ray optics and scintillator-coupled detectors can be achieved with coherent diffraction imaging (CDI) methods. X-rays are diffracted by a sample, and the diffraction patterns are used to reconstruct an image via an iterative feedback algorithm which aims to retrieve the lost phase information. In effect, the objective lens of a typical microscope is replaced by software.

Such methods require highly coherent X-rays and can therefore not be conducted with conventional laboratory sources. The Coherence Branchline (I13-1) uses X-rays in the 6-20 keV range.

In classical CDI, in order to retrieve phase information, some known constraints must be placed on samples. In the early days of CDI, the common constraint placed upon samples was isolation from their environment. This approach is still sometimes used on the Coherence Branchline.

For further CDI techniques visit Ptychography and Bragg CDI.