Adaptive array detector

Fig. 1.4. Examples of fixed array detectors and adaptive array detectors used in commercially available MDCT systems...

The 16-slice CT systems have adaptive array detectors in general. A representative example for this scanner type, the Siemens SOMATOM Sensation 16 scan-... 

Limited temporal resolution - Focal plane arrays are aU inherently framing detectors and knowledge of the arrival time of photons is limited to the frame time of the detector. While the frame time can be quite short for adaptive optics detectors ( 1 ms), in most astronomical instruments the frame time is on the order of seconds or minutes, adequate for most astronomical science, but not all. 

Some spectrophotometric techniques work to enhance sensitivity or utility in other ways. The advent of semiconductor diode array detectors permits entire spectra to be acquired simultaneously instead of one wavelength band at a time. Also, automated spectrophotometric analyzers originally developed for clinical use have been adapted for use at sea when many samples... 

The main components of an LC-MS are the HPLC apparatus, an optional UV or photodiode array detector, the interface, the mass spectrometer and a computer system for data management and evaluation. The interface is the key component of the LC-MS system. All other components must be adapted to the particular interface that is used. Most commercially available systems work with thermospray, electrospray, or particle beam interfaces. Each interface has a distinct mode of action and its own operational parameters. 

The commercial softwares, initially developed by instrament manufacturers for open-access operation, were adapted to enable unattended data acquisition and automated data processing for large series of samples from an autosampler supporting the 96-well microtitre plate format, which is the sample format of choice in combinatorial synthesis. Initially, mainly Gilson 215 or 233 XL autosamplers were used, but other systems have become available from other instrument manufacturers. The complete system is under control of the MS data system. It consists of a 96-well-plate autosampler, an LC pumping system, eventually a UV-photodiode-array detector (DAD) in series and/or evaporative hght scattering (ELSD) detector in parallel, and the mass spectrometer eqnipped with ESI, APCI, and/or atmospheric-pressure photoionization (APPI). 

Adaptability the possibility of outfitting with certain ionization techniques and other ancillary devices, such as multichannel array detectors and chromatographic devices. Coupling a high-resolution separation device to a mass spectrometer helps in the analysis of real-world complex mixtures of samples. 

There are practical equipment limitations that currently prevent the acceptance of UV-Raman spectroscopy as the standard production tool for evaluation of DLC films. Raman spectrometers must be specially adapted for use with UV light. Most common optical materials do not transmit or reflect UV light with high efficiency and the standard front-illuminated CCD array detectors are not sensitive to light below 400 nm. Detector sensi-... 

This chapter will concentrate on the very high quality detectors that are needed in scientific imagers and spectrographs, and other applications that require high sensitivity, such as acquisition and guiding, adaptive optics and interferometry. We limit our discussion to focal plane arrays - large two-dimensional arrays of pixels - as opposed to single pixel detectors (e.g., avalanche photodiodes). 

Figure 4.8. A schematic of a UV-Vis absorbance detector (a) and a photodiode array (PDA) detector (b). Diagrams adapted from and reprinted with permission from Academy Savant.

Flow techniques use a wide range of photometric detectors from simple colorimeters to CCD and diode array spectrophotometers. While photometers typically available in the laboratory are often adapted to flow systems by using an appropriate cell, a number of specially designed detectors are also currently available. 

Modern instruments can be easily adapted to particular requirement in process-control applications. By adopting a particular sampling strategy, sensor array can be operated in the laboratory as well as on-line for process-contfol or environmental-monitoring applications. In the laboratory, the detector can be used with a headspace autosampler. Adsorbent trapping units are also available for on-line measurement with a gas chromatographymass spectrometry(GCMS) instrument. The different sensors are built into a very small sensor chamber and usually can be ordered for a particular application. In other words, the gas detection devices can be easily adapted to particular requirement in process-control applications. 

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