26 October 2004 Automatic geometrical calibration for x-ray microtomography based on Fourier and Radon analysis
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Abstract
In high-resolution microtomography, the alignment of the axis of rotation with respect to the optical axis and to the rows of the detector pixel array is an important issue, misalignment being a critical source of reconstruction artifacts. A common calibration method is based on the use of small fiducial markers on a sample. However, the automatic detection and identification of such markers is difficult. Moreover, the exact determination of their positions in the radiographs is prone to errors in the presence of noise, beam-profile fluctuations or nonuniform detector response. This is largely due to the fact that the markers cover only a small number of pixels in the image, which results in poor signal statistics. We have developed a new method that overcomes this limitation. It is based on the use of a purpose-built reference sample with periodic grid structures that cover large regions of the radiographs. Straightforward Fourier analysis techniques are used to determine from the images not only the tilt angles of the rotation axis, but also the lateral position of the axis and the exact pixel size.
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Timm Weitkamp, Timm Weitkamp, Pierre Bleuet, Pierre Bleuet, } "Automatic geometrical calibration for x-ray microtomography based on Fourier and Radon analysis", Proc. SPIE 5535, Developments in X-Ray Tomography IV, (26 October 2004); doi: 10.1117/12.557094; https://doi.org/10.1117/12.557094
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