Data acquisition for time resolved measurements

X-ray structure determination is a well-established field, and electronic linear and area detectors with their high quantum efficiency have a contribution to make even with conventional X-ray sources. However, with synchrotron radiation sources and electronic detectors, it is now possible to collect significant, time resolved data. Systems where this is of particular interest are biological systems, where the understanding of the biochemistry of motion is still far from complete. At EMBL we have developed over the last year or two a data acquisition system to collect time resolved data, and this has been successfully used by several groups. To date the detectors used have been mainly linear detectors, but area detectors are soon to be incorporated. The main components of the system that will be described are: the time frame generator, a module that adds the time information to the position information from the detector and its read-out electronics; the data accumulation store; the overall data acquisition system; and the general facilities available for analysis. Finally, the developments for the future will be looked at in the data-acquisition and analysis fields. It will be seen that the challenges are not yet over, indeed it might be said that the log-jam of data just moves down the line so that the eventual challenge is to the scientist to interpret the flood of new information. (orig.)