X-Ray Micro-Computed Tomography (Micro-CT)

X-Ray Micro-Computed Tomography (Micro-CT)

Technique:

Similar to a hospital CAT scanning system, Micro Computed Tomography (Micro-CT) is a non-destructive 3D imaging technique (4-D with time-based measurements) that uses a highly energetic X-Ray beam to create a series of 2D projections, whose greyscales vary with the volume’s internal density and atomic number variations. These projections are reconstructed to create a virtual 3D model, allowing users to “see” inside the sample without preparing, sectioning or destroying the sample.

In principal, Micro-CT directs onto a sample a beam of X-Rays that are generated within an X-Ray source; these X-Rays are transmitted through the sample. The efficiency of transmission is dependent on density and atomic number variations within the sample volume, such that higher density materials will transmit less X-Rays than low density materials. The transmitted X-Rays are then magnified onto and recorded by a planar detector as a 2D projection. The sample is rotated by a fraction of a degree and another 2D cross-section image is recorded, which is repeated up to 360 degrees. This series of images is then computed and “reconstructed” into a high-resolution 3D volume, showing internal density variations within the sample.

Instrument:

Zeiss Xradia 410 Versa Micro-CT

System Capabilities:

  • Minimum spatial resolution of 0.9 µm and a minimum voxel size of 100 nm at larger working distances
  • Variable X-Ray voltage from 0 to 150 kV
  • Variable X-Ray power from 0 to 10 W
  • Automated objective carousel, with objectives: 0.4x, 4x, 10x, 20x
  • Advanced absorption and phase contrast capability (for soft or low atomic number materials) overcomes the limitations on traditional computer tomography
  • Vertical stitching mode enables the analysis of taller samples by joining tomographies from different sections of the sample
  • The in-situ tensile stage (5000 N) enables measurements while the samples are under tensile or compression stresses

Selected Applications in Industry:

  • Corrosion analysis within an alloy
  • Distribution of porosities in metals, oil reservoir rocks, and other samples
  • Phase contrast analysis of internal phases
  • Failure analysis of large intact circuit boards and other 3-D packages
  • Non-destructive reverse engineering of obsolete Integrated Circuit packages
  • Defects in polymers and paint coatings
  • Imaging/mapping of biological, pathological, and neural networks
3D micro-CT tomography of a capacitor taken from a computer power source

3D micro-CT tomography of a series of bubbles and cracks in a painted polymer panel