Microfocus

To realize a process integrated quality control the conception shown in fig. 2 was followed. The casting process which is influenced by process parameters like thermal economy, alloy composition or black wash will be pursued with particulary to the problematic nature adjusted sensoring systems. On basic factors orientated sensoring systems like microfocus radioscopy, and tomography will be employed and correlated with sensoring systems which can be applicated under industrial conditions. 

Using microfocus-radioscopy gives the possibility to determine continously the density... 

Stegemann, D, Reimche, W. Schmidtbauer, J. Investigations of Light Metal Casting Processes by Real Time Microfocus Radioscopy. The European Journal of Nondestructive Testing, Vol. l,No. 3, S. 107117, Jan. 1992... 

The divergent shape of the beam provides facilities for magnification in the distances of the source to detector and of the sources to the axis of rotation, which used in conjunction with a microfocus x-ray source opens the way to high resolution. 

This research examines the feasibility of a technique based upon the CT principle using a microfocus X-ray source with an image intensifier while the examined object is being rotated The attainable enlargement is up to 200. The data to be processed is collected from the whole surface of the image intensifier by a frame grabber and noise suppression is performed. 

Obviously, for most applications, the unsharpness associated with M > 1.5, is unacceptable. With a microfocus X-rays system (/of about 8 pm) a magnification of up to 200 might be of use. 

High geometrical magnifications are attainable using a microfocus X-ray source. The capacity and speed of the computing system limits at present the size of the examined objeet volumes. 

Halmshaw R. "Radiography with Microfocus X-Ray Equipment". British Journal of NDT, vol. 36, no. 2, February 1994. 

The volume of defects is calculated using intensity evaluation. Considering the polychromatic radiation of microfocus X-ray tubes the X-ray beam is represented by an energy dependent intensity distribution Io(E). The intensity Ip behind a sample of thickness s is given by integrating the absorption law over all energies ... 

The system for microfocus high speed radiographic testing consists of ... 

For the radiographic testing of the samples a microfocus X-ray tube, manufactured by Feinfokus, Garbsen was used. The X-ray tube has a focal spot, depending on the power, with a diameter from 5 pm to 50 pm. 

The previous investigations of hard particle transport processes during laser beam dispersing have shown, that the high speed microfocus radioscopy system is a usable arrangement to observe and analyse the movements, velocities and accelerations of particles inside the molten bath. That possibility was, until now, not given by conventional techniques of process... 

The investigations show that the microfocus high speed radioscopy system is suitable for monitoring the hard particle transport during laser beam dispersing. It is possible to observe and analyse the processes inside the molten bath with the presented test equipment. As a consequence a basis for correlation with the results of a simulation is available. 

Laminographical approaches can be used for layer-by-layer visualization of the internal microstructure for the flat objects (multilayers, PCBs etc.), that caimot be reconstructed by computerized tomography because of the limited possibilities in rotation. Depth and lateral spatial resolutions are limited by the tube, camera and rotation accuracy. Microfocus X-ray tubes and digital registration techniques with static cameras allow improving resolution. Precision object manipulations and more effective distortion corrections can do further improvement. 

It is shown how phase contrast X-ray microtomography can be realised with a (commercial) polychromatic X-ray microfocus tomograph provided the source size and the resolution of the detector are sufficiently small and the distance between source and detector is sufficiently large. The technique opens perspectives for high resolution tomography of light objects... 

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. 

A continuous lipidic cubic phase is obtained by mixing a long-chain lipid such as monoolein with a small amount of water. The result is a highly viscous state where the lipids are packed in curved continuous bilayers extending in three dimensions and which are interpenetrated by communicating aqueous channels. Crystallization of incorporated proteins starts inside the lipid phase and growth is achieved by lateral diffusion of the protein molecules to the nucleation sites. This system has recently been used to obtain three-dimensional crystals 20 x 20 x 8 pm in size of the membrane protein bacteriorhodopsin, which diffracted to 2 A resolution using a microfocus beam at the European Synchrotron Radiation Facility. 

Sample requirements Any material, greater than "0.5 cm, although smaller with microfocus... 

The obvious application of microfocus Raman spectroscopy is the measurement of individual grains, inclusions, and grain boundary regions in polycrystalline materials. No special surface preparation is needed. Data can be obtained from fresh fracture surfeces, cut and polished surfaces, or natural surfeces. It is also possible to investigate growth zones and phase separated regions if these occur at a scale larger than the 1-2 pm optical focus limitation. 

With the microfocus instrument it is possible to combine the weak Raman scattering of liquid water with a water-immersion lens on the microscope and to determine spectra on precipitates in equilibrium with the mother liquor. Unique among characterization tools, Raman spectroscopy will give structural information on solids that are otherwise unstable when removed from their solutions. 

Stress in crystalline solids produces small shifts, typically a few wavenumbers, in the Raman lines that sometimes are accompanied by a small amount of line broadening. Measurement of a series of Raman spectra in high-pressure equipment under static or uniaxial pressure allows the line shifts to be calibrated in terms of stress level. This information can be used to characterize built-in stress in thin films, along grain boundaries, and in thermally stressed materials. Microfocus spectra can be obtained from crack tips in ceramic material and by a careful spatial mapping along and across the crack estimates can be obtained of the stress fields around the crack. ... 

Raman spectroscopy is a very convenient technique for the identification of crystalline or molecular phases, for obtaining structural information on noncrystalline solids, for identifying molecular species in aqueous solutions, and for characterizing solid—liquid interfaces. Backscattering geometries, especially with microfocus instruments, allow films, coatings, and surfaces to be easily measured. Ambient atmospheres can be used and no special sample preparation is needed. 

A versatile Laser-SNMS instrument consists of a versatile microfocus ion gun, a sputtering ion gun, a liquid metal ion gun, a pulsed flood electron gun, a resonant laser system consisting of a pulsed Nd YAG laser pumping two dye lasers, a non-resonant laser system consisting of a high-power excimer or Nd YAG laser, a computer-controlled high-resolution sample manipulator on which samples can be cooled or heated, a video and electron imaging system, a vacuum lock for sample introduction, and a TOF mass spectrometer. 

Temperatures as high as 2,500 K have been achieved by laser heating (LH). For such LHDAC experiments, the sample size was around 50-100 pm, the laser beam was focused to about 40 pm, and the synchrotron beam was microfocused to about 10 pm in diameter [70]. The photon-flux for the 14.4 keV ( Fe) synchrotron radiation at the focusing spot was about 10 photons s with a 1 meV energy bandwidth. This flux was reduced by a 5 mm path through diamond, via photo absorption, to 25% of its original value. For comparison the flux of the 21.5 keV radiation of Eu would be reduced to only 60%. 

In summary, the NLE technique offers a concepmally new approach to observe NFS. Existing limits for time resolution could be overcome by a microfocused synchrotron beam (as planned for PETRA III) and by detectors with high spatial resolution and background from SAXS could be suppressed by employing high-energy transitions and crystalline sapphire as rotor material. 

Spatial variation of structure in a natural sample or in a technical part (e.g., gradient materials for hip-joints) can be studied by means of microfocus [44] beams (microbeams). The size of the probing X-ray beam limits the spatial resolution. 

Figure 4.7. Microfocus beam shaping by means of a capillary used as a waveguide (ESRF, ID13) (courtesy C. RlEKEL)... 

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