Conclusion

As it was made clear in the introduction of this course, this study does not allow one to understand the notion of the length of coherence of the diode, and thus, the visibility limit of the disturbances in the emission power contingent upon the characteristics of the feedback. Thus in our study, the modulation parameter m, which is also the visibility of the phenomenon of “self-mixing”, appears to be independent of the distance of the object. It should be noted however, that the observation of signals of “self-mixing” is principally limited by the laser-target optical coupling and by the dependence of C with the distance inferring an easily multimodal behavior. For an easily exploitable signal, it is preferable not to go past a distance of a few dozen centimeters.