Wide Dynamic Range Array Detector for Absorbance and Rotation Spectrometry

Photodiode detectors have a limited dynamic range relative to a photomultiplier tube. Sensitivity (in terms of intensity) can be adjusted by changing the integration time, but the integration time for all diodes in array detector is the same for any given scan, and all portions of a spectrum are acquired within the same limited dynamic range. However, the results of scans taken at varying times can be combined to produce a data set with inproved dynamic range. A microprocessor-controlled system for the automatic sequencing of detector integration time and the storage of only the optimum readings is described. An improvement in dynamic range of 215 times that for a single integration time is theoretically possible, but in most systems, stray light and dark current will limit the practical dynamic range attainable.