Research On Numerical Reconstruction Method Of Laser Intensity Distribution Based On Three-plane Image Acquisition

Obtaining the intensity distribution of the laser beam at different positions along the propagation direction is a prerequisite and necessary condition for measuring the quality of the laser beam.At present,light intensity distribution detection technology can be divided into two categories: direct detection method and numerical reconstruction method.Compared with the direct detection method,the measurement system of the numerical reconstruction method is simple and time-consuming,which is the main research direction in recent years.However,the existing numerical reconstruction methods only analyze laser beams with relatively simple light intensity distribution.Fundamentally,these methods have the problems of low measurement accuracy and poor universality.This paper focuses on the study of phase recovery and diffraction numerical calculations in the theory of numerical reconstruction methods,analyzes the reasons for the low calculation accuracy of the two parts,and studies new high-precision phase recovery algorithms and high-precision coherent optical transmission calculation methods.The three-plane-based amplitude gradient phase recovery method is a new algorithm that can invert the phase with high accuracy only requiring light intensities at three different axial positions.The algorithm is based on the framework of the three-plane GS algorithm.In each iteration,the amplitude gradient variable is introduced.The introduction of the gradient variable not only increases the iteration step size but also overcomes the problem of the original algorithm's convergence and easy stagnation.The three-plane amplitude gradient phase recovery method breaks through the traditional GS problems,such as slow convergence speed,poor convergence accuracy,and dependence on initial conditions.This method achieves highprecision phase recovery.The matrix product angular spectrum method is a new diffraction calculation method that does not depend on FFT at all.This method has a high degree of flexibility in sampling control.Based on the characteristics of flexible sampling control,the matrix product angular spectrum method maximizes the utilization of frequency domain sampling points and maximizes the expansion of effective bandwidth.Without changing the calculation window,this method achieves high precision calculation in the far and near fields of coherent light.Based on the above two new algorithms,this paper proposes a universal measurement method that can realize the numerical reconstruction of the laser beam intensity distribution with only three-plane light intensity acquisition.