Transverse Spatial Model Of Light Field And Its Application In Imaging

After diffraction,the point source is no longer a point on the imaging plane,but a diffraction pattern with a certain area.Therefore,when direct imaging is measured,the intensity distribution of the light field of the diffraction pattern is obtained in the imaging plane with respect to the position.In this case,to accurately measure the tiny displacement of the point light source,the information collected by a large number of pixels on the camera needs to be carefully processed.On the other hand,due to the existence of finite numerical aperture in the process of light propagation,some information will be lost and the image will become fuzzy.Therefore,in direct imaging,when the distance between two incoherent point sources is less than the Rayleigh radius,they become indistinguishable,which is the so-called Rayleigh limit.In order to improve the measurement accuracy of the above problems,we adopt the method of optimization measurement.But this requires a precision standard to measure the performance of the measurement.Rayleigh’s criterion,as a classical resolution standard,has its own limitations and is not objective enough.With the development of quantum technology,quantum parameter estimation theory and quantum measurement technology are introduced into the research of imaging problems.With the help of quantum parameter estimation theory,we view measurement as a process of parameter estimation,Cramér-Rao bound is a theoretical tool to measure the measurement accuracy and guide us to optimize the measurement.The measurement method of spatial mode decomposition multiplexing has been theoretically proved.In solving the problem of measuring the displacement of a single point light source and the distance between two incoherent point light sources,it is the optimal measurement scheme.However,to achieve optimization,one condition needs to be met,that is,the probability on all measurement bases needs to be measured,which cannot be achieved in actual measurement.This requires us to develop effective and feasible estimation schemes based on the distribution of Fisher information.A phase-only spatial light modulator equipped with computational holography is used for mode decomposition and multiplexing of optical fields.In this scheme,we use only two measuring bases and only one pixel to measure the tiny displacement of a single point light source,and can effectively resolve two incoherent point light sources in the Ariely region.