Research On Optical Surface's Defect Inspection Based On Scattering And Diffraction

Defects on the surface of optical components will reduce the performance of the optical system.Therefore,during processing and assembly,the detection of defects is essential.At present,the detection of surface defects mainly includes two types:the scattering energy method and the imaging method.The advantage of scattering method is its higher sensitivity and the structure of the device is relatively simple.The characteristic of the imaging method is that it can obtain clear pictures of the defects.For many years,people's research has always been conducted in the direction of obtaining high-sensitivity and intuitive defect images.After development and iteration,detection equipment and solutions for specific surface shapes have been putting forward endlessly.However,for the detection of optical lenses,it is always subject to the differences in calibers,curvature radii,etc.of the element itself.So far,there is no detection device that can be applied to spherical surfaces of various specifications.In this paper,combining the advantages of the scattering energy method and the imaging method,together with the designed specific motion mode of the platform,to achieve better detection of surface defects of different spherical lenses.Main tasks as following:1.Analyze the energy distribution of Mie scattering corresponding to defects such as bubbles and pits,combined with ray tracing simulation,the law of energy distribution of pits and scratches was obtained.Theoretical analysis and simulation were utilized to guide the experiment.The parameters of the device in the experiment,the angle of the light incident on the sample's surface,and the scattered light energy detected in the forward direction were determined2.A platform with specific motion mode was designed,which can realize the spherical surface detection of different specifications.The motion equation of each motor was deduced and realized by PLC programming.In addition,a static experiment was performed to analyze the distribution of scattered energy of defects,which was consistent with the simulation results,and the setting of the illumination threshold was clarified.3.The main error analysis was performed on the platform:the system error of the motor was corrected by the correction factor k,and the allowable range of the random placement error Ax was derived.In addition,samples of different specifications were used in the experiments to obtain clear images of local defects.Performance parameters such as the applicability of the experimental device and the sensitivity of the detection were verified.