To recover phase-shift information, it should be converted to an intensity signal detectable by the X-ray camera. Such a conversion is performed by a special set-up named the Talbot-Lau X-ray interferometer, which contains several absorption and phase-shift gratings with micron-size pitch. The phase grating G1 creates interference pattern with local maxima and minima of intensity. If the object changes the direction of the primary beam, the pattern becomes locally shifted. The absorption grating G2 strips this pattern and converts it to intensity modulation, which can be detected by relatively large pixels in the detector. To create the necessary conditions for interference, an additional absorption grating G0 in front of the X-ray source divides the primary beam into a large number of spatially correlated thin beams. All gratings are precisely aligned to each other.