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Spectroscopy of methane using a vertical cavity surface-emitting laser system with emphasis on development for portable applications
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- Author / Creator
- Dzikowski, Matthew
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There is a great deal of interest in monitoring atmospheric greenhouse gases such as methane. Although distributed feedback edge-emitting lasers are often used for atmospheric detection, the development of the vertical cavity surface-emitting laser (VCSEL) has allowed for an alternative source. The VCSEL exhibits several advantages over distributed feedback (DFB), edge-emitting lasers, especially in terms of power requirements and tuning capabilities. A second harmonic spectroscopy system based on a VCSEL laser is presented. Battery operation of the driver, temperature control and receiver is achieved. The system is used to detect methane gas in open path situations, as well as in gas cylinders. Temperature and current scanning are compared as methods for laser wavelength modulation. Mathematical methods for characterizing and filtering absorption signals are investigated. The receiver system is also used with a DFB laser to compare performance with the VCSEL. A software receiver using LabVIEW is implemented, and its performance is compared with the hardware designs. A minimum detectable limit of 1.4 ppm•m of methane for the hardware receiver is reported.
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- Subjects / Keywords
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- Graduation date
- Fall 2009
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.