Computer modeling for optical waveguide sensors

A two-layer model for the analysis of an optical waveguide chemical vapor sensor is developed using a program written for a low-cost (PC) computer, which takes into account a nonadsorbing glass-fluid interface, the number of optical reflections, and probe beam divergence, for angles of incidence which are skewed about the critical angle for total internal reflection. This model is applied in the analysis of condensed organic vapors employing an uncoated optical thin walled glass capillary device developed at NRL. Reasonable agreement is obtained between the experimental results and model predictions.