The newly developed device for tomographic measurements comprises a sample holder that is designed to rotate the sample around two axis instead of only one axis as usual. Alternatively, one or both sample rotations can be replaced by a joined rotation of radiation source and detector. Hence, the dimensions of the radiation source can now be significantly larger in one direction lateral to the propagation direction than in the second lateral direction, without having a negative impact on the resolution. This anisotropy of the source is compensated by the rotation around two axes which enables different image reconstruction methods. For example the inverse 3D radon transform can be used instead of the 2D radon transform.
For this method, only the size of the source along one of the two lateral dimensions is relevant for the resolution. It is thus possible to use cheaper laboratory sources like for example X-ray tubes. Since with this new procedure it is no longer necessary to restrict the beam, the entire source fluence is available for the measurement. As a result, less measurement time per rotation step is required. Additional rotation steps are introduced by movement around the second rotation axis. However, the overall measurement time remains the same because each single position can be acquired in a shorter amount of time.
Additional advantages of this new procedure can be expected for the sector of local tomography where only few regions of interest are to be acquired with high resolution. Here the inverse 3D radon transform shows less artifacts than the conventional 2D radon transform.