Read-out time

Other analyzers such as the Gilford Automated Enzyme Analyzer and the LKB-8600 Reaction Rate Analyzer analyze discrete samples one at a time. These instruments provide kinetic analyses, digital data reduction at the time each sample is analyzed, and excellent electronic and optical characteristics. Recently, Atwood has developed kinetic enzyme analyzers which require only 9 seconds for measuring an enzyme activity, using highly stable and sensitive electronic circuits (12). This short read out time allows a large number of samples to be processed by one instrument in an automated mode. 

Snively et al. used a PA-IR spectrograph equipped with a 64 x 64 MCT rollingmode FPA to push the time resolution of PA-IR spectroscopy to less than 100 ts per spectrum [27]. The small size and the acquisition mode of this FPA, both contributed to enable such time resolution. First, a smaller FPA allows faster frame rates than a larger one (3.2 ms per image in this specific case), at the expense of bandwidth and/or resolution. Second, the 100% duty cycle of a rolling-mode FPA was put to profit. In a snapshot-mode FPA, all pixels measure the signal intensity simultaneously for -100 ts, but the electronic read-out time can be as... 

The only down sides of cooled CCD cameras have been their relatively slow read-out rate (typically 0.5-1.0 million pixels/sec) and their relatively high cost. For most cell biological applications, the slow read-out rate is not a consideration. For example, in most immunofluorescence applications the camera exposure time is longer than the camera read-out time (typical exposure times of 1-10 sec versus read-out times of 1-2 sec). Cooled CCD camera read-out rates have been entirely adequate for our time-resolved, two-component, three-dimensional recordings of the short mitoses of Drosophila early embryos (Paddy et ai, 1996). However, researchers following very rapid cell phenomena in situ. 

One generation of in vivo scanners now commercially available is capable of a read-out time of 20 ms but with a correspondingly limited spatial resolution (>100 p,m). These scanners are typically used in combination with functional imaging methods, like micro-PET and other nuclear imaging methods, or to make dynamic measurements. 

---