It is government policy to disseminate NASA's research and development innovations to the private sector in order to increase the country's technological competitiveness. The article describes some of the commercial applications for the Linatron-powered Advanced Computed Tomography Inspection System (ACTIS).

50714 Erre, D.; Thomas, X.; Mouze, D.; Patat, J.M.; Trebbia, P.; Cazaux, Prospects of X-ray microscopy and X-ray micro tomography for interface studies Surface and Interface Analysis, Vol. 19, No. 1-12, pp. 89-92 (Jun. 1992)

Miorofocal X-ray projection microscopy allows the non-destructive investigation of thick specimens with a lateral resolution in the micromeue range. The minimum detectable thickness lies below 100 nm for strongly absorbing materials. For further investigation, X-ray microtomography leads to three-dimensional reconstruction of the specimen. Some applications of X-ray microscopy are connected with the localization and imaging of solid/solid interfaces deeply buried in a matrix. In the future, solid/liquid interfaces and their motion will be of interest The performance of X-ray microscopy is discussed and X-ray projection images obtained with a simple modified scanning electron microscope are shown.

50710 Gusev, E.A.; Luk'yanenko, E.A.; Chelnokov, V.B. Soviet combined and semiconductor detectors for X-ray comput ing tomography Russian Journal of Nondestructive Testing, Vol. 28, No. 2, pp. 64-73 (Oct. 1992)

The authors review the state of development of combined and semiconductor detectors for X-ray scanning equipment for inspection and computing tomographs. Combined detectors in the scintillators plus photosensor system with high time characteristics and stable parameters are most promising in the current stage of development of technology.

50706 8ossi, R J-L; Georgeson, G.E. Computed tomography analysis of castings Boeing Defense and Space Group, Seattle, Washington (United States), AD-A249 099/3/GAR, 39 pp. (2 Jan. 1992)

Under a preliminary testing task assignment of the Advanced Development of X-ray Computer Tomography Application program, computed tomography (CT) has been studied for its potential use in the analysis of castings. CT sensitivity to anomaly sizes has been measured by the use of image quality indicators. The sensitivity of a CT system, as a function of object size and system operating parameters, can be estimated and monitored. The three-dimensional location and definition of flaws, obtained from CT evaluation of castings, have been input into finite element engineering models to analyze the performance as a function of the casting condition. Dimensional measurements with excellent accuracies and precision better than 0.050 mm have been demonstrated. The data sets from CT scanning have been converted to CAD/CAM files and input to a Sterv~lithography system to build a 3D plastic model of a part.

50700 Peyrin, F.; Goutte, R.; Amiel, M. Analysis of a cone beam X-ray tomographic system for different scanning modes Journal of the Optical Society of America, Vol. 9, pp. 1554-1563 (Sep. 1992)

Cone beam X-ray tomography is based on the acquisition of two- dimensional projections for different positions of Cone beam X-ray source. Generally the X-ray source describes a single circle around the volume. We consider three different scanning modes: a sphere, a circle, and two orthogonal circles. We study the response of a cone beam reconstruction system defined as the weighted backprojection of the cone beam projections of an arbitrary impulse point. The spatial invariance of the system is discussed for the three acquisition geometries. Exact and approximate reconstruction methods based on three-dimensional convolution are then proposed. Some results obtained from both simulated and experimental data are presented and analyzed.

50453 Nagata, Y.; Yamaji, H.; Hayashi, K.; Kawashima, K.; Hyodo, K.; Kawata, H.; Ando, M. High energy high resolution monochromat ic X-ray computed tomography using synchrotron radiation Nondestructive Testing Evaluation, Vol. 7, No. 1-6, pp. 299-307 (1992)

We have developed a high resolution monochromatic X-ray computed tomography system using synchrotron radiation in the energy range up to 50 keV. The system was installed in a vertical wiggler beamline at the Photon Factory of the National Laboratory for High Energy Physics. The system

ND T Abstracts

consists of a double-crystal monochromator employing asymmetric Bmgg reflectiom, a photodiode array detector with a phosphor screen, and a microcomputer for control. CT images with a pixel size of 7.7 mu m were obtained. An image subtraction technique for CT images above and below the X-ray absorption edge of iodine was also evaluated for liquid-containing glass capillaries. The results indicate that the system is very useful for nondestructively evaluating fine structures and their constituent elements.

50452 Yamauchi, Y.; lkuta, T.; Kishimoto, N. Three-dimensional high resolution tomography for small objects Nondestructive Testing Evaluation, Vol. 7, No. 1-6, pp. 309-318 (1992)

Three dimensional microtomography system using a conventional X-ray source has been developed. The X-ray source using a rotating target is operated in the fine focus mode. The parallel projection configuration is adopted and transmitted X-rays are converted to visible light by the fluorescent screen before detection by a charge coupled device (CCD) still camera. The data acquisition is controlled mainly by a personal computer and the reconstruction is accomplished by a powerful computer accessible through the local area network (LAN). The performance of the apparatus is examined by observing a carbon-fiber/SiC composite. The spatial resolution of less than I0 mum is obtained. The three dimensional image and its capability is demonstrated by showing tomographs at various directions. All the measurements and processing of a matrix of 256 X 192 X 200 data is performed in about three and a half hours.

50448 Goebbels, J.; Heidt, H.; lllerhaus, B.; Muller, W., Reimers, P., Wolff, V. Characterization of typical defect structures of advanced engineering materials by computerized tomography Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 769-778. Edited by T. Kishi, T. Saito, C. Ruud, and R. Green.

Typical properties and defect structures in composites are well characterized by high resolution X-ray tomngraphy. This NDE method can be particularly used in the development of materials to reduce time consuming methods like micrographs. If the time scale is appropriate even time dependent processes like a dry-up procedure can be studied by CT. For large components a Region-of-lnterest method was applied which allows to investigate only the interesting parts of the samples.

50447 Masuda, C.; Tanaka, Y., Usami, K.; Hirano, T.; Imai, Y.; Shiota, L; Furubayashi, E.; lwasala, H. Observation of fibers in long fiber reinforced metal matrix composites by X-ray computed tomngraphy using synchrotron radiation Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 779-786. Edited by T. Kishi, T. Saito, C. Ruud, and R. Green.

Four types of MMC reinforced with B and SiC fibers were observed by X- ray CT using synchrotron radiation. Use of X-ray CT made possible the direct observation of fibers and defects in them. On the basis of X- ray coefficients of the elements in the composites the energy values of 21 and 29 KeV were selected for AI alloy and Ti alloy, respectively. The inner fiber and dehonding parts of the interface between fiber and matrix were clearly observed for the composites used in this study. In the case of the silicon carbide reinforced aluminum composites, the core carbon fibers of 30 mum in diameter were also observed. The resolution of X-ray CT scanner used in this study was about 10 mum. 3-dimensional images were reconstructed from several CT images. The 3- dimensional images visually displayed the inner structure and were very useful in discussing the model of the fracture process of the fibers contained in the metal matrix composites.

50208 Thomas, G. Performance in X-ray tomography application to the inspection of very strong absorbers (In French: English Abstract) Revue Pratique de Controle Industriel, Vol. 173, Iss. 2, pp. 72-78 (Mar. 1992)

X-ray transmission computed tomography is a non destructive method which allows individual object slice imaging. Compared to radiography, the interpretation is easier. In the first part, the general CT principles are listed. In the second part, we point out new technologies in large rockets imaging:-linear accelerator - photoconductive detectors. In the third part, we try to highlight relations between CT construction parameters and CT performance capabilities: - dimensional measurements, --defect sensitivity. density measurements, -inspection time. Finally a little CT with linear

N D T & E International 1994 Volume 27, Number 2 107