A fast derivative-less optimization of the feedback coupling coefficient for a self-mixing laser displacement sensor

An important parameter for achieving displacement measurements with a self-mixing laser sensor is the feedback coupling coefficient. However, its determination necessitates advanced signal processing. In this work, various derivative-less optimization methods (such as Powell´s method, uni-dimensional minimization methods and Nelder Mead Simplex method) have been considered to reduce this computation time. The results of the comparison have been used to propose a new faster hybrid method of optimization that has taken into account the behavior of a Self Mixing laser sensor. This new method makes it possible to envisage the development of a real-time self-mixing micro-interferometer.