Analysis And Modification On Beam Wander Of Optical Measurement Caused By Near-ground Atmospheric Turbulence

The missions of optical measurement are usually conducted in an atmospheric circumstance,and the atmospheric turbulence will do great harm to the measurement result.This phenomenon has been found for years,and several researches have been made in relative fields,but there is no perfect solution for the problem in the field of optical measurement at the moment.In this paper,modification means for the impact of near-ground atmospheric turbulence are studied depend on a realistic mission in optical measurement.The research background of the paper is to measure the position and the attitude of a cooperation object under the near-ground atmospheric turbulence.In the research,a series of experiments designed by the characteristics of near-ground atmospheric turbulence are carried out to indicate an intuitional impression of the disturbance impact.Then the theoretic analysis of the impact is presented with imaging model,and the disturbance is divided into high-frequency part and low-frequency part according to their difference behavior in disturbance process.For the high-frequency part a method based on Kalman filtering is used,while for the low-frequency part a method based on an opposite-observed imaging system is proposed in this paper.Theoretic analysis,simulation and experiment are employed to evaluate the modification effects of the proposed method.The results suggest that the proposed method performs great in the modification for the low-frequency disturbance.The hardcore of the paper mainly contains the following three items: 1.The impact analysis of near-ground atmospheric turbulence on optical imagingFor the phenomenon that the imaging process is disturbed by atmospheric turbulence in optical measurement,the researches for the impact of near-ground atmospheric turbulence are studied based on the characteristics of optical measurement.Some disturbed rules are presented by a series of experiments,which can provide guidance in optical measurement design.The disturbance is divided into high-frequency part and low-frequency part for its disturbed effect,and it is the fundamental of modification.2.The theoretic analysis of the modification method based on an opposite-observed imaging systemIn order to realize the distortion modification of low-frequency disturbance in near-ground atmospheric turbulence,the method based on an opposite-observed imaging system is proposed in this paper.By establishing a disturbance model,theoretic analysis is carried out as a feasibility study of the method.And simulation is presented to evaluate the modification effect of the method.The results indicate that the proposed method performs well in the modification of the disturbance in established model.3.The establishment analysis of opposite-observed imaging system for telecentric cameras and experimental researchesBy theoretic analysis,telecentric cameras are used to establish the proposed opposite-observed imaging system,and the experimental researches are presented based on the system.In the experiment,a flexible calibration method for telecentric lens proposed by the author of this paper is used to realize the calibration of the telecentric camera system with the help of mirror refraction.The results of experiment show that the proposed method is able to realize a large proportion modification of the low-frequency disturbance in near-ground atmospheric turbulence.