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Novel Optical Sensing Technology for Detection of Organic Vapor by Using Semicondector Laser

Talib Zeedan Taban

Abstract


The gas sensor device is required to monitor harmful gases in the environments and industries. Many volatile organic compounds adsorbed on the sensor material will result in changes of the optical properties including the refractive index and the film thickness. Optical detector for organic vapor have been designed by used Michelson interferometer in order to generate laser longitudinal mode interferometer to identify the rate of organic materials. A proposed system consisted of: a gas chamber with a fixed size that injected by organic vapors, the light source which are two semiconductor lasers with wave length (780 nm) and (850 nm) with (5 mW) output power, and a spectrometer that works in optical range between (700 nm) to (900 nm) with (50 pm) resolution in order to analyses the optical spectrum that generated from laser mode interferometer before and after injection process. Furthermore, a three organic materials vapors have been used in this experiment which is (Propane, Hexane and Methanol).

The experimental result shows a positive effect in sensitivity of optical system for detection the chemical vapors ratios as increasing in rate of liner absorption factor of material. From results, the vapor ratio from using 780nm laser shows that the air has (Hexane=1,161), Methanol (1,123), and Propane= (1,204), and the vapor ration for using 850nm laser is (Hexane=1,154), Methanol (1,111) and Propane= (1,189). From these result, it appears that the proposed system is more sensitive to Propane vapor when compared with other materials.


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