Research On Distributed Holographic Aperture Digital Common Phase Technology Based On GPU

High resolution is one of the most important performance indicators for measuring imaging systems.The traditional optical imaging system mainly improves the imaging resolution by increasing the system aperture,but it is difficult to further increase the aperture of the single aperture imaging system due to factors such as optical processing,manufacturing cost,volume weight,and support structure.The distributed aperture imaging system utilizes multiple closely or sparsely arranged small apertures to control the aberration between each small aperture to a sufficiently small range through the common phase technology,so that the imaging resolution of the system is equivalent to a single large aperture system Imaging resolution.Compared with the single-aperture imaging system,the distributed aperture imaging system reduces the process difficulty and also reduces the weight and volume,but how to detect and correct the commonphase error of the sub-aperture in real time is a technical challenge.In the long-distance distributed aperture imaging system,factors such as atmospheric turbulence and system assembly errors make the imaging system have high-order Zernike aberration within the aperture,position mismatch error between apertures,and low-order Zernike aberration between apertures.These errors Will seriously reduce the aperture comprehensive imaging quality.At present,most distributed aperture imaging systems use optical co-phase technology,that is,adaptive optical technology is used to detect and correct the co-phase error of the sub-aperture,so as to realize the coherent superposition of each sub-aperture signal in the optical domain.Its shortcoming is that it not only needs a large number of relay optical systems to realize the combination of different sub-aperture beams,but also requires special aberration measurement and correction devices to control the common phase error before the beam interference.The structure of the optical common-phase system is very complex and is easily affected by external disturbances.With the advancement of electronic information technology,digital distributed aperture imaging technology has gradually developed.This technology first records the wavefront complex amplitude of each sub-aperture beam,and then implements aberration correction(digital co-phase)by digital calculation and Diffraction imaging of virtual aperture.Digital co-phase technology uses flexible software to replace complex optical components to achieve phase correction,which greatly reduces the complexity,volume and difficulty of processing and assembly of the system.The distributed holographic aperture digital imaging system uses holographic technology to record the complex amplitude of each sub-aperture,corrects multiple aberrations through digital common-phase technology,and obtains multi-aperture comprehensive high-resolution images.This paper first studies the principle of the distributed holographic aperture digital imaging system,analyzes the main aberrations and correction methods of the imaging system,and designs a digital co-phase method flow for the distributed imaging system;then analyzes the time of the digital co-phase method The complexity,and for some time-consuming algorithms,the algorithm structure is analyzed,combined with the high-performance platform design algorithm to optimize the acceleration method,the acceleration ratio of the high-order and loworder aberration correction algorithms based on the GPU platform is 26.42 and 36.47,respectively.And designed a distributed holographic aperture digital co-phase method architecture based on CPU-GPU heterogeneous platform;finally built an indoor distributed holographic aperture imaging system,based on the GPU platform to achieve digital co-phase process,and finally realized distributed four aperture comprehensive imaging Compared with single-aperture imaging,the imaging resolution is improved.