BL1.2W: X-ray Tomographic Microscopy
XTM beamline located at BL1.2W is the experimental facility for X-ray tomographic microscopy. With the synchrotron radiation generated from the 2.2-Tesla multipole wiggler of Siam Photon Source (SPS), the XTM beamline offers the high-intensity x-ray beam for microtomography to provide the reconstructed cross-sectional detail and 3D visualization of various kinds of samples at the resolution up to 1 micron (0.72-micron pixel size). Application of X-ray tomographic imaging is suitable for research purposes that aim for characterization in 3D such as the internal morphology, engineering defects, porosity, and pore distribution inside the samples. XTM beamline is now open to academic and industrial users. Thai and international applicants can apply for beamtime online at http://beamapp.slri.or.th
X-ray tomographic microscopy
Synchrotron radiation X-ray Tomographic Microscopy (SRXTM) utilizes the x-ray beam generated from the synchrotron light source in the x-ray imaging. When the x-ray beam is projected onto the sample, the x-ray beam that passes through the sample (transmitted x-ray beam) creates an x-ray pattern from the differential absorption of the sample. To acquire the x-ray image, the scintillator is used to convert the transmitted x-ray to visible light. Then it is magnified by the objective-lens coupled microscope and finally recorded by the high-resolution camera. A typically SRXTM scan is carried out by acquiring the x-ray images around the sample for at least 180 degrees (if the sample is larger than the available field of view of the detection system, multiple scans will be required to satisfy tomographic mathematical calculation). After the scan, all x-ray images are calibrated by flat-field correction with bright and dark current images to remove the effects of image artifacts caused by variations in the pixel-to-pixel sensitivity of the camera and by distortions in the optical path. The preprocessing usually includes noise filtering and beam intensity normalization. The resulting x-ray images are inputted in computational processing to obtain the sinograms and the reconstructed tomographic images based on the filtered back-projection algorithm. The collection of reconstructed images (also referred to as "tomograms") reflects the cross-sectional details of the sample in three dimensions.
Applications of SRXTM
SRXTM is widely applied as for characterization and assessment in diverse research fields. Internal details of the sample can be revealed in 3D via computational reconstructed images which allow for volume presentation of segmented features. Therefore, the sample for SRXTM does not need to be thin-sectioned. Moreover, SRXTM relies on X-ray images resulting from differential absorption (absorption-contrast) and/or refractive index (phase-contrast) of the sample so it requires neither staining nor coating. In biology, entomology, and paleontology, this is very useful in taxonomy study that requires morphology details of fruit seed, small insects, or even fossils. The reconstructed images provide 3D visualization and the segmentation of selected internal features is possible.
Numerous studies have applied SRXTM complementary to SEM or TEM for further information such as voids and porosity. In life science research, it is widely used in examining porosity in femurs or tibiae of animal models and also in scaffolds. In material science research, SRXTM can follow the porosity in geopolymer and polymer microcapsule and present the pore distribution in 3D under different preparation conditions. The pore distribution is also important information in food processing for example baking and roasting.
Ms. Chalermluck Phoovasawat
Tel: 1690 (beamline)
Ms. Nidchakan Boriku
Tel: 1774 (SEM)
Mr. Anuchit Ruangvittayanon
Tel: 1494 (SEM)