Research On Calibration And Stitching Of Sphere Sub Aperture Under 3D Constraint

Inertial Confinement Fusion(ICF)is a method to obtain a large amount of fusion energy by using high-power laser or ion beam to irradiate deuterium and tritium fuel target to achieve ignition conditions under inertial confinement.At present,China and the United States are advancing from principle research to engineering,and every detail needs to be carefully crafted.The target is a key component.Any isolated defects such as bumps and dust on the surface may cause asymmetric implosion or even shell rupture during fusion,causing huge losses.In order to achieve high-precision,high-efficiency,non-contact detection of the entire surface defect of the target,the project uses optical micro-interference technology and 3D global stitching technology to complete an automatic target surface defect measurement system.The measurement speed of the whole surface defect of the target with a diameter of 1-2mm reached the level of 1.5h-3h.Aiming at the limitation of the aperture and depth of field of the microscopic imaging system,as well as the dual requirements of in-plane error correction and out-of-plane error correction in global 3D stitching,this paper deeply studies the sub-aperture calibration and stitching technology of spheres.The combination of theoretical analysis and software simulation was used to determine the depth of field of the microscopic imaging system.A method for calibrating the radius of the target and a method for automatically arranging the subaperture positions of the sphere according to parameters such as the radius of the target were proposed.The calibration method of mapping relationship between spherical and plane was studied,and the problem of non-linear error of lateral resolution of each pixel of sub-aperture was solved.The sub-aperture stitching method of spheres was studied.According to the transformation formula between image plane coordinates and three-dimensional space coordinates and matrix rotation transformation formula,the spherical mapping of hemispherical sub-aperture was realized.The calibration method of the northern and southern hemispheres was studied,and the spatial dislocation caused by the northern and southern hemispheres overturning was solved,and the topographical defects of the entire surface of the sphere were obtained.Finally,an experimental system for the detection of the defects on the whole surface of the target is built,and the samples of glow discharge polymer(GDP)microspheres are measured.According to the proposed sub-aperture calibration and stitching technology,the defect distribution of the entire surface of the sphere is obtained,and the number and size of the defects are counted.The feasibility and effectiveness of the sphere sub-aperture stitching and calibration technology studied in this paper have been proved,which has laid a solid foundation for the preparation of high performance target.