PROBLEM TO BE SOLVED: To prevent an artifact from being generated caused by fluctuation of a grating position between prephotographing and aimed photographing.SOLUTION: Scanning initial positions (k=0) of the first and second absorption type gratings are changed sequentially by ξ, in the prephotographing under a state arranged with no subject, to be moved relatively at a plurality of times (stripe scanning) from the respective initial positions, and the first phase differential images are thereby acquired the plurality of times. The first phase differential image with the moire position nearest to the second phase differential image obtained in the aimed photographing under a state arranged with a subject is selected from the plurality of first phase differential images, and the selected first phase differential image is subtracted from the second phase differential image. The ξ is sufficiently smaller than a scanning pitch (p2/M).COPYRIGHT: (C)2012,JPO&INPIT【課題】プレ撮影と本撮影との間での格子位置の変動によるアーチファクトの発生を防止する。【解決手段】被検体を配置しない状態でのプレ撮影時に、第1及び第2の吸収型格子の走査初期位置(k=0)をξずつ順に変更し、各初期位置から複数回の相対移動(縞走査)を行うことにより、第1の位相微分像を複数取得する。これらの複数の第1の位相微分像から、被検体を配置した状態での本撮影時に得られる第2の位相微分像と、モアレ縞の位置が最も近いものを選択し、選択された第1の位相微分像を、第2の位相微分像から減算する。ξは、走査ピッチ(p2/M)より十分に小さい。【選択図】図6
