L2036H1 (031205c)

Imaging No.: c Sample: IDP (L2036H1) Beamline: BL47XU X-ray photon energy: 7 keV Exposure time for each projection: 1.5 sec. No. of pixels for each projection image: 256 × 140pels No. of projection images for dark current ： 2 (1 each before and after sample imaging) No. of projection images for incident beam current (I 0 ): 151 (+1; for determining the rotation axis) No. of projection images for transmitted beam current (I): 750 (+1; ditto) Imaging sequence: One I 0 imaging after every 5 I imaging Pixel size of projection images: 0.5 micron Voxel size of reconstructed CT images ： 0.5 micron No. of voxels ： 256 × 256 × 140 Location of sample rotation axis: （ z = ） Byte images: PV=0:CT value = 0 1/cm PV=400:CT value = /cm (theoretical LAC of enstatite) Cut images:Threshold: PV=22 Erosion: 3 layers Dilation: 6 layers Voxel size ： 0.5 micron Number of voxels ： 68 × 71 × 93 TLI3 images:Interpolation: 3 ×3 ×3 Voxel size ： micron Number of voxels ： 204 × 213 × 278 cut/33.tif (width: 34 m m)TLI3/99.tif (width: 34 m m)

L2036H1 (031205c) : browse image

L2036H1 (031205c) : external shape +X +Y -Z image +Y -Z +X image +X -Z+Y image -Z +X +Y

L2036H1 (031205c) : frequency diagram and phases LAC of troilite: cm -1 Estimated CT: cm -1 LAC of forsterite: cm -1 Estimated CT: cm -1 LAC of enstatite: cm -1 Estimated CT: cm -1 LAC of serpentine: cm -1 Estimated CT: cm -1 CT value = (651) * LAC TLI3/99.tif Minerals White (CTv >85 cm -1 ):iron sulfide?? Gray (CTv = 70.5 cm -1 :glass fiber Dark gray (CTv = 48.3 cm -1 ):hydrous silicate?? Black:void, air CT values are low compared with LAC of silicates and troilite. glueglass hydrous silicate? Fe sulfide?

L2036H1 (031205c): XRD (T.Nakamura et al.)

Glossary Beamline Three beamlines (BL20B2, BL20XU and BL47XU) are now available at Spring-8 for X-ray microtomography. We can choose the beamline mainly depending on the sample size and the spatial resolution. Browse image Some of a successive CT images of a sample can be seen at a glance by this image. Size scale (cm) and gray scale for CT values (cm -1 ) are shown in the right and left bottoms of the image, respectively. Byte image An monochromatic image where the brightness of each pixel is expressed by 8 bit ( steps). A series of byte images of an sample stored in the directory named “byte” are formed from original CT images by conversion from CT value to PV (usualy the theoretical LAC of a standard mineral is used for this conversion). CT value This is the value of LAC in each pixel of an CT image. In other words, an CT image is expressed as spatial distribution of CT values. CT values are calculated by CT reconstruction. If we use a monochromatic X-ray beam, CT value is ideally equal to the LAC of a material. However, they are not identical with each other in practice. Their empirical relations were determined at BL20B2 and BL47XU of Spring-8 (see np.29 for the relation at BL47XU). From this relation, we can estimate materials from CT values. Cut image This is a CT image, where unnecessary regions without sample are trimmed. A series of cut images of an sample stored in the directory named “cut” are formed from “byte” images by image processing using threshold for a sample and erosion and dilation procedures. Imaging No. Imaging number shows the date of imaging and its order. For example, c shows the third experiment (in alphabetical order) on 4 December, LAC (Linear attenuation coefficient) (of X-ray) A characteristic properties for X-ray attenuation of a material. This is a function of the bulk density, the chemical composition and X-ray photon energy.. Pixel One of many from which a 2-D image is composed. The shape is usually square. Projection image CT images are reconstructed from a series of projection images by rotating a sample by180 degrees. The size of a projection image gives the size of a CT image. For example, projection images of 512 × 220 pixels give 220 CT images of 512 × 512 pixels. Projection image for dark current A projection image without X-ray beam (dark image). This gives back ground of the projection images. Usually, 1 (or 2) dark image(s) is (are) taken before and after sample imaging experiment and their average is used for CT reconstruction calculation. Projection images for incident beam current (I 0 ) A projection image of X-ray beam without sample (I 0 image). This is taken at regular intervals of sample imaging (ussually 5 or 10 intervals).

Coordination system Projection images for transmitted beam current (I) A projection image of sample (I image). The projection, p=ln(I 0 /I), is calculated and used for CT reconstruction. Sample rotation axis The location of a sample rotation axis is required for CT reconstruction. This is called “center value”, which is generally described as a function of the height of a projection image (z: see the coordinate system). For example, the center value is expressed as follows: × z ± （ z = ）. PV (Pixel value) This is the value that expresses the brightness of each pixel of a digital image. For example, the pixel is black and white for PV=0 and 255, respectively, in a byte image. Voxel One of many from which a 3-D image is composed. The shape is usually cubic. +X +Y +Z (0,0,0)

The relation between CT values and LAC determined by imaging standard materials at BL47XU (Nakamura et al., 2003)