Microtomography system

For this experiment, as well as for the microtomography ( 3.2) we used the commercial desktop microtomography system Skyscan 1072 [5], the setup of which is sketched in Figure 1. For this instrument, which is designed to study relatively large objects with a diameter up to 50 mm, the source size is 8 pm, the distance source-detector is about 50 cm and the effective resolution of the detector is about 80 pm. For this system and this object, the global effective resolution a is estimated to be of the order of 50 to 100 pm [6]. 

The high brightness of the microfocal x-ray source enables the microtomography system to operate in two basic modes. These two modes are distinguished by whether the beam is collimated or not and lead to different data acquisition procedures. Also, with the installation of a monochromator, it is possible to perform phase contrast imaging that has a greater sensitivity to density variation than conventional contrast imaging. 

Corrigan NM, Chavez AE, Wisner ER, Boone JM. A multiple detector array helical x-ray microtomography system for specimen imaging. Med Phys 1999 ... 

This opens perspectives for obtaining phase contrast information in a microfocus tomographic system Recently we have developed a desktop X-ray microtomographic system [4] with a spot size of 8 micrometer (70 KeV) and equipped with a (1024) pixel CCD, lens coupled to a scintillator. The system is now commercially available [5], The setup is sketched in Figure 1 In this work we used the system to demonstrate the feasibility for phase contrast microtomography. 

It has been demonstrated that phase contrast microtomography is feasible with a desktop (commercial) X-ray microtomographic system The observations agree well with the theoretical predictions. This opens perspectives for high resolution microtomography of light objects. 

Successful development of such systems will lead to foamed materials having useful stress-absorbing characteristics in addition to controlled physics properties. Although our work in this area is currently in a very early stage, prototype materials have been successfully synthesized and assessed structurally using three-dimensional (3D) X-ray microtomography. The technique offers a unique insight into the internal microstructure of cellular materials (see Fig. 3). The diameter of the mainly open cell pores varies from approximately 100 to 250 pm (the resolution of the instrument is 5 pm), with cell walls of variable thickness. 

Al-Raoush, R.I. Willson, C.S. Extraction of physically-representative pore network from unconsolidated porous media systems using synchrotron microtomography. J. Hydrol. 2005, 300 (1 ), 44. 

Fu XW, Elliott JA, Bentham AC, et al. Application of X-ray microtomography and image processing to the investigation of a compacted granular system. Part Part Syst Char 2006 23(3-4) 229-236. 

The discrete versions of these equations must be fulfilled in liquid-gas voxels (only first equation) and in three-phase voxels (both equations), as highlighted in Fig. 5.44. Volume conservation sets a constraint to the optimization problem. Figure 5.45 shows a result of pore liquid relaxation. Such simulated equilibrium liquid distributions will be validated by microtomography on model systems with larger particles. 

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