A ratio-measuring detection system for use in pulsed spectroscopic measurements

The advantages are discussed of performing certain measurements in a pulsed rather than a continuous manner. A ratio-detection system is described which is suitable for the study of transient phenomena induced by repetitive pulsed excitation. Fast sample-and-hold circuits preserve appropriate measures of the observed phenomena and of the intensity of the excitation source. The ratio of the two signals is taken, reducing by three orders of magnitude the effect of fluctuations of the excitation source. The ratio signal is then averaged in a two-channel `boxcar' circuit linear to ±4 parts in 105 for input voltages between ±2 V The entire system is linear to ±2 parts in 104 for input voltages between ±2 V. Under continuous operation, drifts of the system referred to the input are less than 20 μV per day.