Abstract: A species-specific metal clad segment on a waveguide, including a planar waveguide, allows controlled light leakage of light propagating through the waveguide by total internal reflection, to measure refractive index and identify chemical species. A waveguide sensor is designed for a particular chemical species by selecting a metal clad with an affinity for the species and by matching the refractive indices of the waveguide body, clad, metal clad segment and chemical species. Dual or multiple measurement methods use a pair or multiple metal clad segments of different specificity. The metal clad segment may include another material to provide a suitable refractive index while having the desired affinity for the chemical species or to provide a catalyst to react the species to form a reaction product which is more readily detected.

Abstract: Single or multi-cell reservoir sensors with single illumination sources and one or more detectors per cell unit have an arrangement whereby a gaseous, vapor or liquid sample enters the cell body and interacts with a sensing solution to detect and quantify a given species. Entrance of the sample into the sensor is through an opening in the cell body which may be covered with a membrane to contain the sensing reagent and to presort the species entering the cell. Reservoir cells can be used with organic, inorganic or biochemical sensing materials. A variety of sensors as alcohol, drugs of abuse, organic halides, cyanide and inorganic ions are provided.

Abstract: A fiber optic chemical sensor is made water repellent by attaching a plurality of long, hydrophobic chains, e.g. silane polymers, to the surface. The chains extend from the surface and form a semi-permeable barrier which repels water molecules while selectively passing analyte molecules therethrough. In one configuration, the hydrophobic chains are attached substantially uniformly over the clad. In a second configuration, the clad is a plurality of spaced stripes with the hydrophobic chains attached in the gaps between the stripes. In another configuration, a patterned hydrophobic coating of alternating thick and thin segments is formed on the clad.

Abstract: A reservoir chemical sensor has a sensor body containing a reservoir cell channel around which source and detector are positioned within the cell body. A replaceable modular reservoir cell which contains sensing solution fits snugly and removably in the channel in the sensor body. Different reservoir cells can be easily inserted and removed from the sensor body.

Abstract: A chemical sensor, such as a fiber optic chemical sensor, is self-calibrated by measuring two output values which behave differently in response to an analyte, and forming a ratio between the two measured output values to cancel out effects of variations in external factors such as temperature variations, differences between coatings, light (illuminator) variations, fouling, bleaching, leaching or the like. An indicator material may be used which produces both fluorescence and phosphorescence, both monomer and aggregate emission or absorption bands, emission or absorption bands with or without an isosbestic point, emission peaks at one wavelength at two different excitation bands, or emission peaks at two wavelengths for excitation at two wavelengths.

Abstract: A refractive index FOCS has a fiber optic core with a partly light transmissive thin metal film clad of an effective thickness and light transmissivity so that transmission through the core is strongly affected by the refractive index of a surrounding liquid or vapor medium. The metal clad and surrounding medium produce a localized refractive index at the core interface which modulates light transmission through the core as a function of the medium refractive index. The clad is made of platinum, or also of gold, rhodium, palladium, nickel, iron, cobalt, ruthenium, iridium, osmium, zinc, copper, silver, chronium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium or hafnium. The clad is also made of oxides of these metals, or metal compounds or alloys. With a fluorescent tip, the changes in the fluorescent signal are a measure of the medium refractive index. With a reflective tip, the changes in the reflected signal are measured.

Abstract: An ice sensor for the remote rapid indication of ice formation or the presence of ice is a fiber optic "switch", activated by ice but not by water, and based on the difference in optical properties between water and ice. The approach is to construct a "fiber optic" which itself is the ice sensor. The fiber optic sensor (FOS) is designed so that no light is transmitted when water is present but as soon as ice begins to form, light is relayed. Thus ice switches on the light- In addition, limited quantitative information can be made available on the rate of ice formation. Alternatively the sensor can be formed of another type optical waveguide instead of an optical fiber. The ice sensor is formed by placing spaced stripes of a clad material on a fiber optic core, or other waveguide structure, where the clad has a refractive index close to ice and the core has an index greater than the clad but less than water.

Abstract: A reservoir fiber optic chemical sensor (FOCS) is formed of a modular cell body. A fiber optic is attached using a quick connect standard fiber optic connector. A semipermeable membrane is attached at the opposite end of the cell body using a quick attach membrane retainer. Multiple sensors can be made uniformly. Specific sensors for TCE vapor, O.sub.2 and CO.sub.2 are produced by utilizing a suitable reaction chemistry in the cell. A non-imaging optical focusing element can be included in the cell to increase sensitivity. A reaction cell can be placed adjacent to the reservoir cell with the semi-permeable membrane separating the two cells to produce a photolysis FOCS. TOC and TOCl can be detected with the photolysis FOCS.