kokonaisdiffraktiokuvan

Kokonaisdiffraktiokuvan is a Finnish term used to describe the complete image reconstructed from diffractive measurements, typically within the field of coherent diffractive imaging (CDI) and related techniques. In this context, it refers to the full real-space representation of an object's scattering potential or transmission function, including information that is encoded in the diffraction pattern’s phase, not only its intensity.

In practice, coherent diffraction imaging involves illuminating a specimen with a coherent wave (such as X-rays, electrons, or visible light), recording a diffraction pattern in reciprocal space, and applying phase-retrieval algorithms to recover the phase. The resulting reconstruction yields a real-space image that can represent the object’s electron density or refractive-index variation, and in many cases provides a complex-valued description that combines amplitude and phase information.

Common approaches include CDI and ptychography, as well as near-field and far-field diffraction methods. Successful reconstruction relies on sufficient sampling (oversampling), appropriate constraints, and iterative algorithms such as Gerchberg–Saxton, Fienup-type methods, or hybrid input–output schemes. Ptychography uses overlapping illumination positions to improve robustness and resolution, often producing higher-fidelity “kokonaisdiffraktiokuvan” images.

Applications span materials science, biology, and nanostructured imaging, where lensless or lens-free approaches enable high spatial resolution without traditional imaging optics. Advantages include reduced lens aberrations and the ability to probe specimens in situ or under extreme conditions, while challenges encompass phase retrieval ambiguities, missing data due to beam stops, noise sensitivity, radiation damage, and substantial computational demands.