Control Of Beam Deflection Technique Liquid Crystal Optical Phased Array Based

As a kind of technology of non-mechanical beam steering, Liquid CrystalOptical Phased Array(LCOPA) has the advantage of small in size, light in weight,low-power and easily to control. It will improve the problem of beam acquiring,tracking and pointing in the field of free spaces optical communication. The basictheory of the LCOPA is blazed grating, LCOPA can modulate wave front phasethrough imitating the spatial distributing of blazed grating. So the light will spread tothe other direction when pass on it.In this paper, we start the work from the Liquid Crystal Spatial Light Modulator(LCSLM), because it’s the representational product of the technology of LCOPA. Atfirst, the principle of beam steering has been analyzed and simulated, therefore thecomputing method of the beam steering angle and the characteristic of lightdiffraction has been acquired. Then, the test and demonstration of the characteristic ofbeam steering about the reflected256×256LCSLM of Boulder Nonlinear Systemshas been fulfilled, and conclude that LCSLM is a near linear component after gammacalibration, which suit to do some research about control on it. The next, the closedloop control system experiment platform of small-angle beam steering based LCSLMhas been designed and set up, and the system bandwidth based on CCD detection hasbeen tested and analyzed by proportion-integral control arithmetic, the resultdemonstrates that the system bandwidth is determined severely by one-step iterativetime. So the closed loop control system based on PSD detection has been processed toimprove the system bandwidth, and the test result has proved it positively. And then aparticular method of inputting matrix directly has been adopted, the sampling time isreduced seriously, so that the system bandwidth is improved to the highest in certaincondition. At last, in order to improve the range of the steering angle, an innovativemethod, which extending the beam steering angle by cascade Wollaston prism toreach the target of wide-angle beam steering, is put forward.And the feasibility of thismethod has been demonstrated by some simulation and experiment, So this is veryimportant to the coarse tracking in the non-mechanical beam acquiring and tracking system.