Reversible optical waveguide vapor sensor

DETAILED DESCRIPTION Accordingly, it is an object of the invention to detect small amounts of a chemical in air and in other gases.
Another object is to provide a device for such purpose which can be used repeatedly without permanent degradation.
These and other objects of the invention are achieved by an oxazine perchlorate device which includes an optical waveguide, a dye film coated on the waveguide, and means for detecting a change in the optical trasmittance of the waveguide.
The dye film has the property of changing from its normal color to another color when exposed to a chemical, wherein the chemical is ammonia, hydrazine, or pyridine and returning to its original color when the chemical is removed.
The optical transmittance of the waveguide varies with the color of the dye film coating, thereby providing a sensitive indicator of the presence of the chemical.
One advantage and unique feature of the device is its relatively rapid reversible response to wide ranges of chemical concentrations at room temperature without permanent degradation of the dye film.
Another advantage is that the transmittance change-detecting means can be made compact in size through the use of the latest developments in solid state microelectronic technology, i.
e.
small LED's phototransistors, operational amplifiers etc.
The device has the capability of being further scaled down using the techniques of integrated optics and electronics without losing its detection capabilities.
Use of a capillary tube for the optical waveguide in one embodiment allows the optical beam to reflect on itself many times.
This results in sensitivity to wide optical transmittance changes which is enhanced many times over then when conventional cylindrical rods are used.
Lastly, the device consists of readily available and inexpensive components.
Additional advantages and features will become apparent as the subject invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: