SIGNAL-TO-NOISE OPTIMIZATION AND EVALUATION OF A HOME-MADE VISIBLE DIODE-ARRAY SPECTROPHOTOMETER

This paper describes a simple low-cost multichannel visible spectropho tometer built with an RL512G EGG-Reticon photodiode array. A symmetric Czerny-Turner optical design was employed; instrument control was via a single-board microcomputer based on the 8085 Intel microprocessor. Spectral intensity data are stored in the single-board's RAM and then transferred to an IBM-AT 386SX compatible microcomputer processes the data to recover transmittance, absorbance or relative intensity of the spectra. The signal-to-noise ratio and dynamic range were improved by using variable integration times, which increase during the same scan ; and by the use of either weighted or unweighted sliding average of c onsecutive diodes. The instrument is suitable for automatic methods re quiring quasi-simultaneous multiwavelength detections, such as multiva riative calibration and flow-injection gradient scan techniques.