High Presicion Spatial Optical Modulation And Its Application In Receiver Beamforming

Digital Beamforming(DBF)technology is widely used in the signal processing of phased array radar.There are many algorithms and techniques available.The traditional DBF architecture is based on digital signal processors.However,the ability of digital signal processors is challenged with higher and higher requirements on target detection and resolution,an increasing number of channels,and an increasing amount of data processing.Traditional digital processing methods based on semiconductor devices have been exposed inadequately and urgently need to find new ways of processing.Because of the many advantages of optical processing,researchers turn their attention to optical processing.Compared with the traditional digital signal processing,optical information processing has its own characteristics and advantages.First of all,the optical information processing has the high density of information carrying capacity,to meet the mass data processing;Second,the optical signal processing speed by the optical wave propagation speed of the decision,to meet our real-time signal processing requirements.Finally,most of the optical components required for optical signal processing are passive,the power of active devices is low,and the device is small and portable enough to accommodate and meet the data processing needs in a wide variety of situations.Based on the principle of optics and data processing,this paper proposes a high-precision super-pixel data processing method which can modulate the phase and amplitude of space light at the same time.Combining the simulation and experiment,Modulate the module,and use this module as the technological basis and apply to the principle demonstration prototype of the beamforming technology that the receiving end of the broadband phased array radar receives.In this optical system,we use Digital Micromirror Device(DMD)as a loading tool for data to be processed to complete electro-optical conversion and modulate digital data onto the laser's wavefront.The Fourier transform of the convex lens is used to transform the data into the frequency domain to complete the spatial matched filtering.Finally,CCD(Charge-coupled Device)and the wavefront detector on the optical modulation results were collected in real time.As the input data is continuously updated,the modulation results of the data are obtained in real time on the CCD and the wavefront detector.Then we introduce the application of high precision spatial light modulation in beamforming at the receiving end of wideband phased array radar,and our optical broadband DBF system can accomplish beamforming up to 8 beams.Finally,the calibration of amplitude and phase of the spatial light modulation technique is analyzed in this paper.The error and compensation method of the system are analyzed.As the core of the entire optical modulation system,the DMD modulation module has a data refresh rate of up to 15000 Hz and a phase resolution of 0.002 rad.The spatial light modulation technology proposed in this paper is very different from the spatial light modulation technology based on SLM(Spatial Light Modulator)and the spatial light modulation technology abroad.It takes full advantage of the computing power of optics and incorporates today's common data processing algorithms into optical systems.Compared with the traditional phase amplitude modulator,DMD-based spatial light modulation technology has a greater range and higher accuracy,and faster processing speed.