X-ray mapping by EDS techniques of rough samples or samples with a complex topographic surface is more difficult than mapping relatively smooth surfaces. The problem of the sample with a rough surface arises because a lower intensity of an element, or even no intensity, can either mean the absence of that element or it can mean the element has a significant presence but the area can not be "viewed" by the EDS detector (Fig. 1). This problem or ambiguity can be partially solved by the use of a second detector which would ideally have an opposing view. The use of a second detector still presents some problems of interpretation in that there is a contrast artifact arising from the fact that some areas of the sample produce x rays which can be received by both detectors, while the x rays from other areas are detected by only one or by neither of the two detectors [1]. This artifact originates from the simple summing of the x rays from the two detectors (Fig. 1c). A method is presented that can work around this problem and will provide a better interpretation of the chemical variability within the sample.When two detectors are used each detector will have its own spectral map dataset or data cube and the two datasets are merged in a variety of ways to produce a third dataset. The merging can be done by the summing or averaging of the spectral data at each pixel (Fig. 1c). A preferred method would be to merge only the spectral information from the detector that had the most counts at each pixel and to ignore the counts from the detector that had a lower, or a much lower intensity (Fig. 1d). Although it might seem counter-intuitive that some data should be discarded, this eliminates most of the problem of the contrast artifact and will tend to equalize the contrast between areas that are able to have x rays counted by both detectors as compared to those areas where the x rays are seen by only one detector. The contrast artifact is often greatly diminished but not completely eliminated by selecting the information from the detector with the maximum intensity. The chemical contrast may be enhanced as compared to topographic effects by an additional normalization step. The normalization procedure that has been used to a positive effect is a full quantification (ZAF Wt. %) of the merged map data (Fig. 2).There is still a need to either eliminate the data for the pixels that are shadowed in the view of both detectors or to indicate in some way that the data in the maps for these regions are not reliable (note the noisy data in Fig. 2a from some of the voids). A map can be created from the summing of all counts of all energies on a pixel by pixel basis for each detector and these maps can be summed for the 2 detector case. Dark areas of this map represent areas in the shadow of both detectors. If the map is inverted and rendered as a binary image, it can be used as an overlay against a single map or with several maps (Figs. 1 and 2) and the "null" areas where no x rays are detected will be shown in white. When overlain with ...

Fourier-transform profilometry (FTP) and data-dependent system profilometry (DDSP) are the two major phase-extraction methods that use a single interferogram. The difficulty in verifying surface profiles obtained by these methods is that the exact spot on an actual surface cannot be measured with two different instruments. An interferogram regeneration procedure is developed to solve this problem. The surface profile is then extracted from the regenerated interferogram by both FTP and DDSP. Comparisons of the actual surface profile with the extracted surface profiles show that both methods perform equally well in measuring the root mean square and the center line average, but only DDSP is able to reproduce the detailed surface profile of the reference surface.

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We report the results of a bilateral comparison of attenuation measurements between the National Physical Laboratory (NPLI, New Delhi) and the Standards and Calibration Laboratory (SCL, Hong Kong), carried out under the Asia-Pacific Metrology Programme. Commercial 50 coaxial attenuators (in APC-7 connectors), of nominal attenuation values 3 dB, 10 dB and 20 dB, were calibrated at 30 MHz, 5 GHz and 10 GHz against the 30 MHz standard WBCO attenuators of both laboratories. A direct 30 MHz series-substitution technique and a 30 MHz intermediate-frequency substitution technique were employed at the NPLI to calibrate attenuators at 30 MHz and microwave frequencies using a VM-3 attenuator and signal calibrator, respectively. The same techniques were used at the SCL in association with a vector signal analyser (HP-89441A). The expanded uncertainty as measured at the NPLI, quoted at the 95 % confidence level for the attenuation range 3 dB to 20 dB, varies from 0.007 dB to 0.015 dB at 30 MHz, 0.017 dB to 0.032 dB at 5 GHz, and 0.020 dB to 0.037 dB at 10 GHz. The uncertainty reported by the SCL for the same attenuation range is approximately 0.010 dB at 30 MHz and varies from 0.010 dB to 0.016 dB at 5 GHz, and 0.016 dB to 0.023 dB at 10 GHz. The mean values of the measured attenuation of both laboratories were found to lie within the quoted limits of the uncertainties.

Fourier-transform profilometry (FTP) and data-dependent systems profilometry (DDSP) are two methods that are available for recovering one-dimensional fine surface profiles from the phase of a single interferogram. FTP has already been extended to two-dimensional surfaces; a similar extension of DDSP is introduced here. Inasmuch as this extension involves autoregressive modeling of the rows or columns of an interferogram, the feasibility of using a common model order is explored. The common order reduces not only the amount of computation but also the errors caused by the heterodyned phase-removal procedure. As autoregression requires masking the first few data values, the length of the mask is determined by means of a Green's function. A comparison shows that DDSP outperforms FTP in roughness measurements in terms of rms and center-line average. The comparison also shows that DDSP is able to recover a detailed surface, whereas FTP outlines only the global features. An interferogram regeneration procedure provides a reference surface for the verification of results.