X resolution

Figure 3.20. Optical micrograph of a pearlitic steel (note the lamellar regions) that has been partially transformed to spheroidite. Image taken at 2,000 x resolution. Photograph courtesy of US Steel Corporation.

In order to obtain statistical information out of 2D images, the following process was carried out the empty phase was selected by the pixel intensity in two stages (i) first, the superficial fraction at double resolution of the studied scale was empirically determined by the intensity, (ii) then the intensity at the studied resolution was automatically selected by the superficial fraction of the first stage. In this work, intensity at lOOOx resolution fixes the superficial fraction of 500 x resolution, and 10,000 x resolution fixes the superficial fraction of 5000 x resolution. This allows the study of a predetermined area with higher resolution. Figure 2.10 shows schematically this initial process (PI) on a sample micrograph. 

Micro-pores scale at a 5000 x resolution, where we can obtain samples of 12 xm. 

It is important to point out that the nano-metric scale ( inside an agglomerate scale) was not experimentally studied. Nevertheless, the CL internal micro-structure was characterized at 5000 x resolution. In this scale we can define stochastic micro-pores but it is not possible to define CL primary components (Pt, C and ionomer). On the other hand, because the DECAL technique (used for the fabrication of CLs) generates very thin CLs (10-20 p.m), the 500 x resolution characterizes a macro-superficial and isotropic structure. 

X = resolution of inspection P = perimeter estimate 6 = fractal dimension... 

Entamoeba invadens In vivo. Chromatoid bodies Helical. 600 t wide Repeat distance 1290 % EN reconstruction at 107-129 X resolution a... 

Chick embryo In vivo after incidwtion at low temperature P4 crystalline monolayer 537 jt unit cell EN reconstruction work (data at 60 X resolution) b.c... 

Lacerta sicula (Ii sard) oocytes Ribosomal bodies formed during winter rest. vivo Nembrane bound P422 double layer crystals 595 % unit cell CN reconstruction. 90 X resolution d.e... 

E. coli 30S Ethanol, vapor diffusion Helices or ribbons 320x180 % Axial repeat 220 A Optical diffraction of EN (60 X resolution possible) h... 

B. atearo SOS. coli SOS Organic solvents, vapor diffusion Three dimensional crystals EN reconstruction possible to. AO X resolution. X-ray diffraction (powder) observed to 3.5 X resolution i j... 

Offord, R.E., Priddle, J.D., and Waley, S.G., 1975, Structure of chicken muscle triose phosphate isomerase determined crystallographically at 2.5 X resolution using amino acid sequence data. Nature, 255 609. 

Systems, based on a method of inspection of slice by slice, in a number of cases allow to solve put problems. But for obtaining of higher resolution it is necessary to have an opportunity to increase number of inspected slices. It results in significant increasing of collection data time that is inadmissible in some applications. Besides this, the maximum allowable number of researched slices is rigidly limited by hardware opportunities of tomographs, and also by level of emission of x-ray sources. 

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. 

The results regarding resolution as measured by CERL double wire IQI s show results for a class G2 film very close to those obtained by X-rays. Some results from the large range of published data are summarized in fig. 5 and 6. 

Application of experimental devices allows to perform NDT of products, made out of materials of low density (Al-Mg - alloys, Be, plastics) with high defectoscopic sensitivity up to 0,5 %. Inch-size X-ray vidicons used complete with microfocal X-ray tubes and X-ray image enlargement method allow to obtain resolution up to SO pairs of lines per mm. 

In this paper the technical specifications of a Real Time X-Ray system are given. The procedure for inspection is explained briefly. The resolution of film and of Real Time X-Ray inspection are compared. The basic equipment needed to inspect Real Time X-Ray data is defined. 

The resolution of images of the Real Time X-Ray system depend on the material thickness and on the settings of the system. While setting up the Real Time X-Ray inspection of parts the resolution is compared with the resolution aehieved in film bases X-Ray as used over the last years. It is demonstrated that the sensitivity of Real Time X-Ray meets the specification of DIN 54109 Bildgtitteklasse II. 

P ) The system BAS 2000 (bio-imaging analyser) from Fuji Film. The system included flexible IP s, in a 20 X 40 cm and 20 X 25 cm format (type BAS ni) and an IP without proteetive layer (BAS-TR2040). With the system s laser scanner (flat bed) one can read these IP s with a resolution of 100 pm or 200 pm and a digital dynamie of 8 or 10 bits. The system is not on the market anymore. 

Several tests have been performed with the biomedical systems of Fuji Film, the BAS 2500 and BAS 5000. The BAS25(K) is similar to the BAS2000 a flat bed scatmer which can read diverse IP-sizes up to 20 x 40 cm. The read out resolution can be set up to 100 pm or 50 pm. The BAS5000, is based on a new confocal read out optic which is... 

The pixel resolution is 50 pm or 25 pm. Unfortunately (from the point of NDT), the max. IP-size is limited to 20 x 25 cm. The max. image size amounts to 160 MByte. Both systems are equipped with new types of IP s. 

The sensitivity of the luminescence IP s in the systems employed here decreases with increasing x-ray energy more strongly than in the case of x-ray film. Therefore, this phenomenon must be compensated by using thicker lead front and back screens. The specific contrast c,p [1,3] is an appropriate parameter for a comparison between IP s and film, since it may be measured independently of the spatial resolution. Since the absorption coefficient p remains roughly constant for constant tube voltage and the same material, it suffices to measure and compare the scatter ratio k. Fig. 2 shows k as a function of the front and back screen thickness for the IP s for 400 keV and different wall thicknesses. The corresponding measured scatter ratios for x-ray films with 0,1 mm front and back screens of lead are likewise shown. The equivalent value for the front and back screen thicknesses is found from the intersection of the curves for the IP s and the film value. 

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