Proceedings Article | 12 February 2007
Proc. SPIE. 6457, Free-Space Laser Communication Technologies XIX and Atmospheric Propagation of Electromagnetic Waves
KEYWORDS: Beam steering, Control systems, Telecommunications, Acquisition tracking and pointing, Bragg cells, Electronic filtering, Laser communications, Control systems design, Filtering (signal processing), Laser systems engineering
For many practical needs, laser communication systems must support operation between mobile platforms.
Engineering robust links; however, will depend on several innovations. In particular, successful pointing,
acquisition, and tracking (PAT) require the use of a beacon signal and the capability of accurate and agile
alignment of the line-of-sight (LOS) between the communicating terminals performed over a large field of
regard. While mechanical devices, such as gimbals, offer relatively slow tracking over a very wide range,
they lack in pointing bandwidth necessary for rejecting high frequency vibrations and beam deflection
caused by the optical turbulence. In contrast, fast steering and especially non-mechanical devices, such as
Bragg cells, enjoy very high bandwidth (on the order of several kHz), but their effective range is very
small. Inherent limitations of both gimbals and fast steerers result in shortcomings of the entire PAT
system when either of these devices is used as a sole beam steerer. Therefore, focus needs to be shifted to
hybrid architectures, exploiting the advantages of the constituting elements. This paper demonstrates a
system combining a robotic manipulator with two acousto-optic cells and presents the algorithm
development and the simulation results.
