There is an ever-increasing demand for high data transfer rates. Laser satellite communication is a promising technology which offers high data rates and more secure links than the mature radio frequency (RF) communication. To make a laser communication terminal market viable it must be low size, weight and power (SWaP). The telescope drives the volume of the terminal. Making the telescope more compact with high magnification imposes stricter tolerances. A solution to alleviate these tolerances is to use a refocusing mechanism (RFM) to align the telescope in space after launch. In this project, a refocusing system is designed. This comprises of making system level choices like where to place the mechanism, how to close the loop and how to use the onboard detectors. All these choices lead to the requirements for the RFM. Further, a mechanism is designed that fulfills the requirements. In addition, mechanical and thermal FEM simulations are carried out to show that the RFM survives launch and can work in the challenging thermal environment.

Global internet traffic is subject to exponential growth. Free Space Optical communication can accommodate for this increase. Current communication systems prove to be capable of transferring Terabits/s of data per link to and from a satellite. This is done by coupling the laser beam into a fiber, which is connected to a computer capable of processing the data in the laser beam. The downside of these systems is that they require position sensors to accurately steer the beam into the fiber. These sensors limit the amount of light reaching the receiver and thereby limit data capacity. Furthermore, these sensors may drift due to thermal loads, causing the system to lose performance. By removing the position sensor and implementing the gradient-based algorithm Extremum Seeking Control, the same performance can be achieved without risk of fiber drift. Furthermore, this approach would reduce system complexity, relax tolerances imposed on these systems and most importantly, increase the average fiber coupling efficiency of satellite links by 40%. This is verified by a simulink model and breadboard experiment.