Research And Optimization Of Adaptive Optics Wave-front Processing System

Adaptive optics system can real-time correct the wave-front dynamic error caused byatmospheric turbulence and other factors, to maintain the best working condition ofthe optical system, and to response rapidly to adapt to external changes. The systemin general is composed three parts, the wave-front sensor, wave-front processor andwave-front corrector, and wave-front processor is the core part of the whole system,which implements the function of getting information from the wave-front sensor tocontrol the wave-front corrector output conversion. In this article according to theexisting hardware platform of laboratory, the software applications, algorithms andother aspects of the wave-front processing system has been implemented andoptimized, in order to meet the high demand of large ground-based high resolutionimaging telescope for processing scale and computing speed.Firstly, the use of matrix vector multiplication decomposability completehigh-speed parallel wave-front reconstruction calculations, wave-front reconstructioncalculations can be carried out as soon as getting the first sub-aperture centroiddeviation data, which takes full advantage of the spare lines and readout time ofsub-aperture aperture row during wave-front gradient calculation process, andshorten the wave-front processing time delay.Secondly, FPGA-based wave-front control algorithm is proposed, and thewave-front controlling module can be executed in blocks to improve computational efficiency. Control calculation and the previous wave-front reconstructioncalculation can be effective combined. Control algorithm can calculatedsimultaneously as soon as obtaining the first error vector, to avoid the delay ofwaiting calculation data.Then, the wave-front processor PC program is optimized to achieve the functionthat real-time calculation parameters can be configured through the host computer.Finally, a fault diagnostic system (FDS) for this wave-front processor isproposed in this paper. According to the requirement while debugging and operating,the system can provide real-time feedback of the results and states from each part ofthe wave-front processor to up PC, in order to check calculation results of each stage,orientate the breakdown and analyze data error.Closed-loop experiment has been carried out in the optimized system of21-element and137-element adaptive optics system, and the experimental results areanalyzed in detail. The obtained results show that: the corrected image energyconcentration increased more than5times after correction, the wave-front errorsafter correction decrease obviously and the whole wave-front processing operationcan be completed170.29μs before the end of the frame synchronization signal.Experimental results successfully demonstrate the feasibility of the proposedwave-front processing algorithm and fault diagnostic system.