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Analysis and Control of Speckle Effects in Self-Mixing Interferometry. Application to motor shaft monitoring

Presentación a cargo de Reza Atashkhooei (CD6) de los resultados obtenidos en el análisis de los efectos del patrón de speckle en la interferometría de tipo self-mixing y su aplicación en la monitorización de la rotación del eje de motores eléctricos. A continuación se incluye el abstract del trabajo presentado en el IEEE Sensors 2011 Conference (Limerick, Irlanda) y en el que también han colaborado Francisco Azcona (CD6), Osman Zabit (LAAS, Toulouse) y Santiago Royo (CD6) .

An analysis of speckle effects in self-mixing interferometry signals has been performed. We will characterize the effect of surface roughness and laser spot size on the speckle modulation of the signal, and we will propose two simple experimental approaches to overcome the amplitude fading induced by speckle effect. Differently to the techniques proposed up to the moment, our first approach uses an adaptive optical element in the form of a voltage programmable liquid lens, which adaptively changes its focal length to modify the speckle pattern. Our second approach combines two laser signals which present different performance parameters. By using any of these simple methods, the introduction of inaccuracies in the measurement process due to speckle is avoided.