Technologies based upon active remote sensing can, therefore, be adapted for use in multidirectional sensor links. This chapter introduces the novel active remote sensing structure. It techniques for optical differential triangulation are presented with theory and methodology. The chapter associates with its fabrication and operational principle. It focuses on the experimental free-space optical sensing and communication applications. The chapter completes retrodetector construction can be used as an active control device for optimizing the incident optical signal alignment, as a strong dependence exists among the individual photodiodes (PDs) photocurrent levels and the incident light ray components. The geometrical nature of this architecture allows it to act as a retroreflector by reflecting a fraction of the incident light back to its source, while local sensing is facilitated by the use of PDs. The complete theoretical model for the PD photocurrents, including these internal reflections, is developed in this detection characteristics subsection.