Optimization of a Fluorescence Detection System for the Characterization of Solids

Abstract

The optimization of a robust fluorescence detection system is described in which both scattered excitation light and collected fluorescence emission from rock, core, or cutting samples are guided by optical fibers. Analysis of solids poses increased difficulties compared to the extensively studied analysis of liquids; large and variable scattered light can lead to substantial reduction of the system dynamic range and to significant optical noise without proper rejection of the scattered source light. In addition, optical component fluorescence must be minimized; optimization and final optical component selections were based upon the system throughput as well as the system dynamic range. The optimized design was found by analysis of the individual system components—specifically, the source, launch objectives, fiber optics, output collimation optics, and filters. A system dynamic range of 5.1 optical density was achieved, and system performance was demonstrated with fluorescence yield measurements on a variety of solid samples.