Charge-coupled devices readout

An improvement to this technique will be to use a continuous blue/UV light source and replacing the PMT by a compact spectrometer coupled to a CCD (charge-coupled device) for readout, thus accelerating the data acquisition. In the latter case, the scanning and evaluation takes a few milliseconds. 

The multiwire devices, though workhorses for about 10 years, were an intermediate in the development of the detectors we use today. They provided excellent data, but even faster, more reliable, more accurate devices became available in the late 1980s. The instruments that we use today fall into two categories those based on what are called image plates, and those based on charge coupled devices (CCD) detectors. While CCD detectors are now exclusively used at synchrotrons because of their almost instantaneous readout of data, necessary with high intensity sources with short exposure times, most university and private laboratories continue to use detectors based on image plates. 

The use of a CCD array for measurement of the absorbance is similar to the use of a diode array. We briefly discuss the important differences. Charge-coupled device arrays have far lower levels of dark noise than diode arrays and proportionally lower levels of readout noise. A research-grade CCD array... 

These Initial Investigations of the charge Injection device have Indicated that the device promises to be a successful detector for simultaneous multielement analysis In atomic emission spectrometry. The unique non-destructive readout, coupled with selective knockdown and pseudo-random addressing give the CID system capabilities unparalleled in any other detector available today. The device has been shown to have at least an adequate sensitivity, can be operated in a manner which reduces pixel cross talk, and the dynamic range of the system can be extended to virtually any desired level. 

Charge coupled detectors These devices are not yet commonly available in commercial instrumentation for analytical spectrophotometry although they are used in applications in inductively coupled plasma atomic emission spectrometry. However, they have found extensive application in imaging and astronomical applications. Essentially they are two-dimensional photodiode arrays which allow many spectra to be acquired in one readout. A typical array sensor is shown in Figure 9. 

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