Extended Dynamic Range

Figure 4.4 Schematic (a) and photograph of ion detector with extended dynamic range (b) in the double-focusing sector field mass spectrometer Element. (Reproduced by permission of Thermo Fisher Scientific, Bremen.)...

In the Kelly-Lochbaum and one-multiply scattering junctions, because they are structurally lossless, we need only double the number of bits at the output of each multiplier, and add one bit of extended dynamic range at the output of each two-input adder. The final outgoing waves are thereby exactly computed before they are finally rounded to the working precision and/or clipped to the maximum representable magnitude. 

Finally, material problems arise from the constraints dictated by aseptic culture conditions, bio compatibility and the necessity to measure over extended dynamic ranges which often make the construction of sensors rather difficult. 

The Faraday cup is a simple electrode that intercepts tire ion beam directly. This current is then amplified using electronic amplifiers. Because the Faraday cup measures signal intensity directly, rather than indirectly (as in saturation-prone electron multipliers) it provides an absolute measure of ion current and is also useful when signal levels are too high for electron multiplier-based detection. Some instruments use both electron multiplier- and Faraday cup-based detection to provide for extended dynamic range, a capability that can be especially useful for elemental analysis of trace metals in samples. 

The opto-electric conversion characteristic can be designed as linear or nonlinear. A linear CMOS imager experiences numerous drawbacks that are typically known with CCDs, especially the limited dynamic range. Several developments of nonlinear imagers with an extended dynamic range have been presented. 

R. Tryzell, B. Karlberg, Comparison of various peak evaluation techniques for limited and extended dynamic ranges in flow injection systems, Anal. Chim. Acta 364 (1998) 97. 

Detection methods based on the post-electrophoretic staining of proteins with fluorescent compounds have the potential of increased sensitivity combined with an extended dynamic range for improved quantitation. The most commonly used reagents are the SYPRO series of dyes from Molecular Probes (Patton, 2000). Extensive studies have been carried out to evaluate the sensitivity of these fluorescent dyes compared with silver staining (Berggren et al., 2002 Lopez et al., 2000). In our laboratory (Yan et al.,... 

Owing to the added constraints of Time of Flight mass filter-based SIMS instm-ments (these only use MCP detectors), additional options have had to be developed. The two most common approaches include the use of the Poisson statistic correction approach and the introduction of the Extended Dynamic Range (EDR) filter. The Poisson correction approach, apphed during data collection, is a statistic method that attempts to correct for the dead time effect suffered. Although effective, this method is applicable only over a limited intensity range, i.e. the maximum... 

A variant of the Plasmaquad PQ2 is the Plasmaquad PQ2 plus instrument. This latter instrument has improved detector technology which incorporates a multimode system that can measure higher concentrations of elements without compromising the inherent sensitivity of the instrument. This extended dynamic range system (Table 1.3) produces... 

EDR An abbreviation for the term extended dynamic range, used in detector... 

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