A differential amplifier circuit for reducing noise in axial light loss measurements

Abstract

Simplified electronics have been developed for reducing laser excitation source light intensity fluctuations in flow cytometric axial light loss (extinction) measurements. By continuously monitoring the laser output with a photodiode detector and combining it with the axial light loss signal from a second detector using a high‐speed differential amplifier, background interference is reduced 10 to 40 dB. Oscilloscope waveforms and frequency distribution histograms recorded from uniform‐size polystyrene latex spheres and human mononuclear blood cells are used to illustrate the noise reduction capabilities. Copyright © 1983 Wiley‐Liss, Inc.