Correction method for differential phase contrast imaging

A method for, via an interferometer setup for imaging an object by means of electromagnetic waves or matter waves, reducing the influence of induced phase errors on image quality, said setup having an optical axis, wherein the object causes an altered phase information of the electromagnetic waves or matter waves according to a local refraction index, said setup comprising a radiation source for emitting electromagnetic waves or matter waves for transmission through said object, a radiation detector for detecting these electromagnetic waves or matter waves and a pixel-correcting processor for gaining information representative of the object's local phase gradient (∂Φ(x, y)/∂x) in at least one transverse direction perpendicular to the interferometer setup's optical axis,

• wherein said method comprises the steps of:
• determining the pixel positions of noisy pixels and/or determining at which pixel positions of a detected phase gradient image the local phase gradient exceeds a predefined threshold value and marking all these pixels as “bad”;
• performing a line integration over the local phase gradient, thus yielding an integrated phase gradient image;
• analyzing the integrated phase gradient image for characteristic line artifacts occurring behind pixels of strong phase gradient which have been marked as “bad”;
• and
• introducing a correction phase offset of 2π radians or an integer multiple thereof at the position of each “bad” pixel if analysis shows that a measured 2π phase offset error or an integer multiple thereof between immediately adjacent line artifacts which is induced by said line integration persists after passing a pixel that has been marked as “bad” so as to compensate this 2π phase offset error or an integer multiple thereof.

A non-transitory computer readable medium embodying a program for, via an interferometer setup for imaging an object by means of electromagnetic waves or matter waves, reducing the influence of induced phase errors on the image quality of an apparatus serving as said setup, said setup having an optical axis, wherein the object causes an altered phase information of the electromagnetic waves or matter waves according to a local refraction index, the apparatus comprising a radiation source for emitting electromagnetic waves or matter waves for transmission through said object, a radiation detector for detecting these electromagnetic waves or matter waves and a pixel-correcting processor for gaining information representative of the object's local phase gradient (∂Φ(x, y)/∂x) in at least one transverse direction perpendicular to the interferometer setup's optical axis, said program having instructions executable by a processor for carrying out a plurality of acts, among said plurality there being the acts of:

• determining the pixel positions of noisy pixels and/or determining at which pixel positions of a detected phase gradient image the local phase gradient exceeds a predefined threshold value and marking all these pixels as “bad”;
• performing a line integration over the local phase gradient, thus yielding an integrated phase gradient image;
• analyzing the integrated phase gradient image for characteristic line artifacts occurring behind pixels of strong phase gradient which have been marked as “bad”;
• and
• introducing a correction phase offset of 2π radians or an integer multiple thereof at the position of each “bad” pixel if analysis shows that a measured 2π phase offset error or an integer multiple thereof between immediately adjacent line artifacts Which is induced by said line integration persists after passing a pixel that has been marked as “had” so as to compensate this 2π phase offset error or an integer multiple thereof.