ANALYTICAL QUANTIFICATION AND PROCESS CONTROL

摘要

A method and device for high speed spectroscopic constituent verification. The method includes the steps of illuminating a sample with broadband light and measuring two preselected wavelengths of reflected light: a first narrow-range of wavelengths lambda 1 that is not significantly absorbed by the constituent of interest, and a second narrow-range of wavelengths lambda 2 that is substantially absorbed by the constituent of interest. Given the two measurements of reflection, upper and lower thresholds are determined (the latter based on a percentage of the measured baseline reflected light of wavelengths lambda 1). Finally, the presence of the constituent of interest is indicated if the measure of the reflected discriminant wavelength lambda 1 is within te upper and lower threshold measures of reflected baseline light lambda 1. The compact device that implements the above-described method includes a base unit housing a near-IR discriminator circuit with a pair of selective light sensors, and a light source. A sensor unit connects to the base unit. The sensor unit includes a flexible neck with a connecting block attached at one end for mating with the base unit, and a hood assembly attached at the other end for enclosing a light collecting and transmitting lens. The optics are connected by an optical fiber bundle inside the flexible neck.