OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 laminography provides the best spatial resolution in those directions along which there is no data loss, i.e. outside the missing cones. The sample axis direction kz highlighted in Fig. 6 is oriented parallel to the incident X-ray beam. The reciprocal space region obtained after the Fourier transform of one two-dimensional projection and highlighted in Fig. 6 b in gray is a plane parallel to the vectors ku and kv.. When constructing a large number of projections, the analyzed area forms a rotationally symmetric body, the outer contour of which has the form of a hyperbolic surface described by the equation: 2 2 2 max ( ) tan 2 xy z z k k k k = + Θ, where max 1 2 p k s = , p s – pixel size. Fig. 6, b shows that there are no two cones with an opening angle of 2θ. This is explained by the tilt of the rotation axis when implementing the SRCL method. The loss of information in one direction due to the lack of a certain amount of data can be compensated by an increase in spatial resolution in other directions. The use of monochromatic radiation in the implementation of the SRCL method is a factor that ensures high spatial resolution up to micron and submicron scales. The maximum resolution of the method is determined by the characteristics of the detector. Using nanolaminography, images with a resolution of ~100 nm were obtained [15]. If spatial resolution is not a defining requirement, neutron laminography can be used which has the advantage of being sensitive to chemical elements other than X-rays. Features of the adaptation of the laminography method for neutron imaging are presented in [12]. Comparison of laminography and tomography methods. Augmented laminography method When using the method of computed laminography, an isotropic beam scanning scheme is implemented which provides the same resolution and sensitivity in directions perpendicular to the axis of rotation. As mentioned earlier, this characteristic of the CL method gives excellent results compared to the limited angle CT method. a b Fig. 6. Reciprocal space regions obtained using the Fourier transform: a – SRCT-scan; b – SRCL-scan. Cones of missing information are marked in blue [2]
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