Research On Technology In High Precision Laser Beam Combining And Optical Axis Pointing Control

As an important part of laser countermeasure,laser active jamming technology has been a hotspot and frontier problem in scientific fields all over the world.As the input of laser active jamming system,the laser beam combining and control system has a great influence on laser Irradiation.This paper is aimed at the laser beam combining and control system,and the main study are on the laser beam combination scheme,the monitoring and correction of the beam combining system,the propagation characteristics of the combined beam,and the beam combining precision analysis and detection.This paper adopts the scheme of Wavelength beam combination within incoherent beam combining.Compared to coherent beam combining and other incoherent beam combining,it can complete the multi-wavelength beam combination,with high efficiency,simple structure,low cost and high thermal damage resistance,and it is easy to realize in engineering.In the beam combining system,three visible laser beams with different wavelengths are combined together by the transmission and reflection of coated interference filter,and the precision monitoring and closed-loop control of the combined beam are accomplished by the CCD and the two-dimensional fast steering mirror.At the same time,the precisionof laser beam combination and the power index of laser are analyzed and calculated.And lastly,the selections of materials and parameters about the coating filters which is the key components of the beam combination are completed.A direct monitoring scheme of the light leakage and lens method are carried out in the beam monitoring and calibration system.By the beam splitter,the combined beams are divided into two parts,the reflected beams into the launch system,and transmitted beams(leaky light)into the monitoring system.The switching wheel in the monitoring system can be used to select the wavelength of the combined beams,thus accomplishing the Multi-beam real-time angle monitoring in company with a achromatic lens.According to the requirement of the project,the size and the mounting and fixing method of mirrors are determined,and two-dimensional rotating platforms of piezoelectric ceramic with flexible shaft structure and the CCD image sensor are chosen as the driving mechanisms of fast steering mirrors and angle measuring element,respectively.We analyzes the commonly used sub-pixel location algorithms of beam spot center,and finally uses the image processing technology of the iterative threshold segmentation and the barycenter method of two element linear interpolation to locate the center of the beam spot and analyzes the measurement error.An accurate description of the tilted beam is presented,and a method a virtual optical system is established for the processing of inclined beams with the first-order approximation of tilt and off-axis distances.The base vector array methods in multi-bodykinematicsis used to analyze the pose transformation of non-axisymmetric components,and it can solve the propagation of tilted beam through non-axisymmetric element in company with the virtual optical system and the theory of misaligned non-axisymmetric system.The error between the simulation result from ZEMAX of a tilted beamand the theoretical result of thevirtual optical system is less than 2‰.Based on the method and results of tilted beams through a non-axisymmetric element,it is concluded that the tilted TEM00 Gaussian beam can still be regarded asatilted TEM00 Gaussian beam after passing through a tilted filter.According to this characteristics,a precision analysis model for combined beam is given with parameters(a0,b0,?x,?y),namely the inclination angles and off-axis distances of tilted beams,and the beam combining elements are divided into three kinds of functional elements as-45° transmission mirror,45°reflection mirror,-45°reflection mirror.In the light of the tilted beam parameter transform by the beam combined elements,the rationality of the beam precision monitoring is analyzed,and the conclusion that the beam combining accuracy is better than 9.136? is obtained from the facet of error.In this paper,the principle error of lens method detection for beam combining accuracy is analyzed,and the conclusion that the beam combining accuracy can be accurately measured by increasing the focal length fof the lens and decreasing the defocusing ?z is obtained.The experiment for the detection of beam combining precision is designed,and the error between experimental and theoretical data is less than 7.55%.