Research On Optical Measurement Method Of Mechanical Properties Of Optical Glass

Aiming that the measurement methods of existing optical glass mechanical have the disadvantages,like long measuring period,large consumes,easy to damage and difficult to measure small samples,a optical measurement method is proposed to measure the bending stiffness,elastic modulus and Poisson ratio of small samples of optical flat glass.The analytical formula among the bending stiffness,elastic modulus,Poisson's ratio and Newton ring interference image of optical flat glass were deduced by means of plate theory and Newton's ring principle.The stress of the optical flat glass and the radius of the black spot in the center of the image were measured by the self-designed Newton ring stress measuring device.The experimental results show that the relative error of measured bending stiffness does not exceed 6.9%in the range of 29.02 N-38.66 N,and the relative error is less than 11%in the range of 16.07 N-29.02 N.The relative error of the elastic modulus is-2.8%at a stress of 30.90 N.The Poisson's ratio has a relative error of 9.4%at a stress of 35.58 N.Theoretical and experimental results demonstrate the feasibility of using Newton rings to measure the mechanical properties of optical flat glass such as bending stiffness,elastic modulus,and Poisson's ratio.On the basis of the experimental research of the previous research results,a CMOS camera monitoring and photographing interface program based on the MFC was designed.The interference image of Newton's rings can be obtained by CMOS camera.Aiming at the captured images,a method of identifying black spots in the center of Newton ring optical interference image was proposed.The main research work is as follows:Firstly,based on the force characteristics between the Newton ring device flat glass and the Plano-Convex lens,and combined with the current dimensions of the micro-stress sensor,a measurement model of the tilting Newton ring is proposed.The modified Newton ring pressurizing device is designed and made to measure the central stress.Secondly,in light of the force characteristics of the plano-convex lens and the flat glass,the theoretical formula of the bending stiffness,the elastic modulus and Poisson's ratio of the optical glass are derived based on the flat plate theory and the Newton ring optical interference principle.Thirdly,based on the theoretical formula,the Newton ring optical interference image under different stress center dark spot radius was measured through a large number of experiments and the results are calculated by the theoretical formula.In addition,the experimental measurement are compared with the nominal values to verify the correctness of the theory.Fourthly,the interface program of CMOS camera monitoring and photographing based on MFC was designed Fifth,Newton's ring light Interference images are gathered by the acquisition device and the programmed camera monitoring and camera program.Newton ring light interference image center dark spots are identified and calculated.