Research On The Accuracy Of Inclined Extraction Of The Far-field Spots Of Sub-aperture Retro Array Based On CP/CM System

Badcock first proposed the basic concept of adaptive optics in 1953.The main idea is to compensate wavefront distortion in real time while reduce the wavefront aberration at the pupil,and finally achieve the purpose of improving the quality of the system image.After nearly 70 years of development,adaptive optics technology has become an indispensable part of various advanced optical systems,such as high-resolution imaging telescopes,laser fusion systems,retinal imaging systems,and free-space optical communication systems,etc.There are different requirements for adaptive optics in different situations.For the case of correction of wavefront distortion for atmospheric transmission of laser beams,it's required that the adaptive optics system can simultaneously purify the laser beam and detect and correct the wavefront aberration caused by atmospheric turbulence.Based on the concept of Common Path/Common Mode Adaptive Optics proposed by Kenneth W.Billman,researchers in China's adaptive optics technology independently developed the all optical path aberration correction adaptive optical system.This all optical path aberration correction adaptive optical system enables detection and correction of all optical path aberrations,and has a high degree of integration and reliability.Started from solving the practical application of the project,this paper studied the problem of Hartmann sensor for stabilizing the beam does not effectively stabilize the laser beam due to the wide beam jitter spectrum(from low frequency around 30 Hz to high frequency above 200Hz)in the laser system.We proposed the idea of using the far-field spot of the sub-aperture retro array to stabilize the laser beam,and carried out corresponding data simulation and experimental verification research.The main work we have done include:Firstly,by analyzing the jitter spectrum and far-field spot characteristics in the laser system,we proposed a solution to the problem of laser beam stabilization using the far field spot generated by the sub-aperture retro array.We simulated and analyzed the conventional far-field spot and far-field spot from the sub-aperture retro array.And finally found out the centroid shift of the far-field spot of the sub-aperture retro array can truly represents the centroid shift of the laser spot.Secondly,we simulated and analyzed incident wavefront with different tilt in PV value and different array duty cycles of the sub-aperture retro array.We obtained the specific deviation of the angular extraction accuracy of the far-field spot of the sub-aperture retro array and the conventional far-field spot.It provides the guiding significance for practical engineering application.Thirdly,we carried out the confirmatory experiments on the accuracy of the tilt extraction of the far-field spot and the conventional far-field spot under different incident wavefront tilt.The experimental data obtained by the optical contrast system is not completely consistent with the simulation results,but the deviation is basically controlled within 5 pixels.There are many factors,such as the incident wavefront tilt change cannot be controlled in practical experiments,assembly errors of actual sub-aperture retro array cannot be measured one by one,actual parallel laser source beam diameter cannot be expanded to cover the entire 61-unit sub-aperture retro array and other factors.From the experimental data,the tilt extraction by the far-field spot of the sub-aperture retro array array satisfies the system's requirement for tilt extraction accuracy.This work has important guiding value for the practical application of tilt extraction with the far field spot of sub-aperture retro array.With the method proposed in this paper we successfully solved the problem of laser optical axis stability in the system.