Research On Compensation Method Of Atmospheric Loss In Laser Energy Transmission

Laser energy transmission is a technique that uses air as a medium to transmit energy in the form of electromagnetic waves.The long-distance energy transfer of laser as a carrier is a hot research topic.The disturbance of atmospheric turbulence in the air causes the wavefront phase distortion of the laser beam at the receiving end,resulting in uneven distribution of the target spot and causing serious transmission energy loss.In order to solve the influence of atmospheric turbulence during laser transmission,a set of energy compensation scheme based on adaptive optics technology is proposed.The adaptive optics system used includes a wavefront sensor,a wavefront controller,and a wavefront corrector,where the correlation correction algorithm of the wavefront corrector directly affects the energy compensation effect.The paper deeply analyzes the working mechanism of the proposed adaptive optical energy compensation system,models the transmission channel according to the Kolmogorov turbulence theory,and uses the Zernike polynomial to fit the wavefront aberration caused by the atmospheric turbulence channel.On this basis,the research on the laser energy transmission atmospheric attenuation compensation algorithm is carried out,and the specific algorithm of the wavefront controller is simulated.Firstly,the stochastic parallel gradient descent algorithm(SPGD)is used in the wavefront controller to explore the compensation effect of SPGD algorithm on laser energy transmission under the initial aberrations formed by different atmospheric turbulence disturbances.The results show that SPGD has a good convergence effect on discrete spots caused by atmospheric turbulence.Under the correction of the SPGD algorithm,the energy concentration at the receiving end is significantly improved.In order to verify the universal applicability of the system more comprehensively,the correction effect of SPGD algorithm under different turbulence intensities is compared.The results show that the SPGD algorithm can show better convergence under different turbulence disturbance strengths.However,the system also has a slow convergence rate and the SPGD algorithm is easy to fall into the local optimum value,which will seriously affect the performance of the energy compensation system.Then,the paper proposes a SPGD algorithm that combines machine learning methods to solve the appeal drawbacks of the traditional SPGD algorithm.It introduces a deep learning method in the wavefront controller,and designs a convolutional neural network model(CNN)to classify the wavefront image directly corresponding to the initial voltage required by the wavefront corrector.The model can classify and learn the spot images generated by different atmospheric turbulence under the premise that the learning samples are sufficient.After the model is trained,the image of the atmospheric turbulent wavefront spot equivalent to an arbitrary set of Zernike coefficients can be classified by the CNN model.The results show that the SPGD algorithm combined with the CNN method significantly improves the response speed of the whole energy transmission system,and the local convergence problem is suppressed,and the efficiency of the laser energy transmission system is also improved.In this paper,the loss compensation method of laser energy transmission in the process of atmospheric propagation is studied.Two sets of solutions are proposed,which improve the energy transmission efficiency of the system to a certain extent,and provide practical application for laser energy compensation in the future.The corresponding theoretical guidance.