Bonse-Hart x-ray interferometer and tomography

Ulrich Bonse left a great mark on the development of x-ray CT technology. Here, his another great achievement in x-ray optics is highlighted, which is known as “Bonse-Hart x-ray interferometer” developed in collaboration with Michael Hart. These two contributions by him are closely related to my research; I reported the first phase-contrast x-ray computed tomography by combining Bonse-Hart interferometry and tomography. The Bonse-Hart interferometer had already been realized in 1965 thanks to its monolithic structure that allowed stability in the angstrom-scale region. This invention opened up various opportunities in the experiments with hard x-rays and even neutrons. Phase-contrast x-ray computed tomography is one of them. In memory of Ulrich Bonse, an overview of the interferometer is given, and the early stage of the development of phase-contrast x-ray computed tomography and its current status are described.