Experiment Study On Orbital Polishing Process Of BK7 Optical Glass

Large aperture planar optical glass components are widely reguired in the Inertial laser Fusion(ICF)system.In order to ensure the precision of laser targeting and system security,stringent requirements on the processing of optical glass have been made.Continuous polishing(CP)has been the primary method to polish Large aperture optical planar glass for its full spectrum evenly removal ability,high polishing accuracy,and low production cost.But the continuous polishing technology of our country relies heavily on technician’s experience.which lowering the fabrication efficiency severely.The key reason is that we do not clear about the laws of material removal rate in the process of polishing and the fabrication parameters’ effect on the polished optical surface.In this thesis,the material removal volume of BK7 optical planar glass was studied,and based on this,the material removal rate of BK7 optical glass was further studied,and the mathematical model of its material removal rate was established.The technological parameters were optimized with the guidance of the material removal rate mathematical model.The BK7 optical glass with a diameter of 300 mm was fabricated with the guidance of previous theory and technological experiments,the main content is as follows:1)The material removal volume and the polished surface quality of the of BK7 optical glass were studied in the continuous polishing machine with the polishing disc revolution speed and the polishing pressure as experimental variables.2)On the basis of previous experiments,the material removal rate of BK7 optical glass was further studied,and based on Preston equation,the mathematical model of its material removal rate was established.3)The effects of revolution speed ratio,workpeice eccentricity and conditioner eccentricity on the polished surface of BK7 optical glass were studied in the active continuous polishing machine.The process of polishing was analyzed and improved with the previous theory.and ultra-precision polished surface of BK7 optical glasses(Φ100mm)were fabricated with PV value of 0.09λ and 0.2λ(λ=632.8nm).4)The BK7 optical glass with a diameter of 300 mm was fabricated with the guidance of previous chapters’ theory and technological experiments,and the processing requirement was reached successfully.Aiming at explaining the phenomenon of "collapse" of the workpiece during the polishing process,the pressure in the polishing contact area was simulated,and found that the inhomogeneity of the workpiece material removal volume can be reduced effectively by loading on the back of the workpiece.