Effect of insufficient temporal coherence on visibility contrast in X-ray grating interferometry

X-ray grating interferometry, which has been spotlighted in the last decade as a multi-modal X-ray imaging technique, can provide three independent images, i.e., absorption, di erential-phase, and visibility-contrast images. We report on a cause of the visibility contrast, an e ect of insu cient temporal coherence, that can be observed when continuous-spectrum X-rays are used. This e ect occurs even for a sample without unresolvable random structures, which are known as the main causes of visibility contrast. We performed an experiment using an acrylic cylinder and quantitatively explained the visibility contrast due to this e ect.