Autoalignment module for free space laser communications

Nowadays, communication networks and wireless technologies offer an ever higher transport capacity. Following the trend, there is an increasing need for high bandwidth technologies in the last mile. Free space optic networks are a viable solution as they can provide high bandwidth without the need for expensive and more difficult to deploy cable infrastructure [1][2]. However, FSO transmissions pose new problems, such as maintaining the alignment between the transmitter and the receiver [3], especially for a thin, weakly divergent laser signal. This article presents a novel solution for the automatic alignment of the receiver with the transmitter, using servo-electric mechanisms. It begins with a brief overview of free space optics and then presents the general system design, with emphasis on the servo-electric mechanisms. The text presents several misalignment situations and outlines the control system derived from these situations. Included are some tests to prove that the system works as intended.