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URA Archive
Scholars 2008 - 2009

Aurelius Graninger, Computer Engineering

"Stand-Off Chemical Detection Using Acoustic Beam Forming and Photoacoustic Sensing"
Faculty Mentor: Dr. Fow-Sen Choa
Expected Graduation Date: Spring 2009

The goal of this project is to develop a new method for standoff chemical detection by combining elements of acoustic beam forming and photoacoustic spectroscopy. By using microphone arrays, acoustic beams will be formed that will enable us to listen in to a specific point in space where a given chemical or gas may exist. Two Quantum Cascade Lasers will then be aimed such that the cross-point of their beams overlaps with the cross-point of the acoustic beams. The QCLs will then be modulated until their wavelengths match the vibrational energy of the given gas molecule. The subsequent heat that is generated from this excitation will emanate sound waves, which will be detected by the microphone array. We will use a Field Programmable Gate Array to process the acquired spectrum and identify the gas. Using this system, we can dynamically tune the lasers to determine the presence and density of a given gas, and by shifting the cross-point, we can map the density in the surrounding location.