The Research Of Non-mechanical Beam Steering Controller In Laser Communication

The technology of space laser communication, with its confidentiality, stronganti-jamming capability, large information capacity, low power consumption andconvenience, is the new filed of the space communication. And in the space lasercommunication system, there are new non-mechanical beam steering controltechnologies, such as the liquid crystal beam steering technology, the acoustic-opticalsteering technology and the electro-optic steering technology, in which thedevelopment of the liquid crystal beam steering technology is particularly prominent.The key of the liquid crystal beam steering technology is the liquid crystal opticalphased array (LCOPA), which can be modulated from the spatial distributing ofblazed grating. The LCOPA can modulate the phase of the light wave, so as toachieve the purpose of changing the direction of the beam.In this paper, Liquid Crystal Spatial Light Modulator (LCSLM), used in beamsteering control system, is researched firstly. LCSLM is based on the theory ofpure-phase modulation, which can achieve the real-time and programmable controlfor optical phase. And it’s smaller, lighter and lower power consumptive in anon-mechanical way, so it’s widely used. In this paper, a pure-phase reflectiveLCSLM Pluto is described firstly, and then the principle of beam steering is analyzed.The factors which effecting the steering angle, the diffraction efficiency, the gratingconstant and the degree of linear and coupling are researched. And the systemresponse time is tested. According to the theoretical analysis, a new experimentalprogram is proposed to improve the system performance. And the beam steeringcontroller made up of FPGA and DSP will replace the PC to control the beam steeringsystem. The need of the beam steering controller is given. The design points of thebeam steering controller are introduced, including the algorithm of gray value on DSP,the data interface between FPGA and DSP, the DVI transmission module and internalclock module and so on. Subsequently, the algorithm of gray value and the DVIoutput module are tested and verified to ensure the correctness of the data and timing.Finally, the beam steering control system is built based on the beam steeringcontroller, and the response time of the beam steering system is tested. It’s proved thatbeam steering control system can work correctly and the response time of the system reduces to almost half of that of the old system.