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

Presentació a càrrec de Reza Atashkhooei (CD6) dels resultats obtinguts en l'anàlisi dels efectes del patró d'speckle en la interferometria de tipus self-mixing i la seva aplicació a la monitorització de la rotació de l'eix de motors elèctrics. A continuació s'inclou l'abstract del treball presentat al IEEE Sensors 2011 Conference (Limerick, Irlanda) i en el que també hi han col·laborat Francisco Azcona (CD6), Usman Zabit (LAAS, Toulouse) i 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.