A COMPACT FREQUENCY-DOMAIN FLUOROMETER WITH A DIRECTLY MODULATED DEUTERIUM LIGHT-SOURCE

A phase fluorometer based on a low-cost and versatile high-frequency m odulated light source and a fast gain-modulated photomultiplier is des cribed. The apparatus is particularly well-suited to high-sensitivity frequency-domain fluorescence measurements requiring ultraviolet excit ation. The system is very compact since it features a directly modulat ed light source, a miniature photomultiplier tube, and an rf synthesiz er on a PC board. Equipped with a suitable fiber optic probe sensor, t he device has potential as a portable unit for a wide range of remote sensing applications. The lamp can be modulated at frequencies up to 1 20 MHz and the phase fluorometer has been tested at up to 70 MHz with a range of fluorescent lifetime standards containing quinine sulfate q uenched with sodium chloride. (C) 1996 American Institute of Physics.