APPLICATIONS OF FIBER-OPTICS AND DIODE ARRAYS FOR THE MEASUREMENT OF DYNAMIC CHANGES IN LIQUID AND SOLID THIN FILMS

Abstract

A method is developed to measure transmittance and reflectance pattern either to calculate changes in concentration according to Lambert-Beer's law or to determine the product of optical pathlength times refractive index. Both can be obtained in thin films, polymers or in flow systems. The real as well as the imaginary part of the dispersion curve can be used. The apparatus contains a polychromatic light source, a combined dispersive element, and a diode array both adjusted in a ceramic body inaffected by surrounding conditions (fig. 1). An Y-fiber optic (reflectance) or two single fibers respectively (transmittance) are used to observe the sample, which is a newly developed ultra microflow cell or a thin film. Process control, evaluation and graphics are obtained by a specially programmed work station, \containing a 68020/68881 on a VME-bus system, using the real time operating system PDOS. Fig. 2 gives the optical pathway from the light source (in the cell or the thin film) to the polychromator of the diode array.