Research And Application Of Subsurface Damage Technology Based On Fluorescence Microscopy

With the development of high-power laser systems and large-scale optical systems,performance requirements such as optical component stability,image quality,coating quality,and laser damage threshold are more stringent.Subsurface damage of components can greatly reduce these performance indicators.Therefore,it is particularly important to detect the subsurface damage of components,and detection methods are widely investigated in the industry field.In this paper,the measurement technique based on fluorescence microscopy is proposed to measure subsurface damage information of optical components.Firstly,the fluorescence theory of cerium oxide is analyzed and the fluorescence effect of cerium oxide abrasive is verified by experiments.The excitation wavelength and emission wavelength of cerium oxide are obtained.According to the measurement principle of fluorescence microscopy,the subsurface and surface damage measurement system of large-diameter optical components is designed.By designing the laser illumination system,the Gaussian beam is shaped into a flat-top beam with uniform intensity,which reduces the effect of fluorescence quenching effect.An infinite tube length microscopic imaging system is designed to realize the fluorescence imaging and scatter imaging,and the conversion of large and small fields of view is realized by objective lens switching.The auto-focus system is designed to realize the automatic focusing system during the measurement process.Surface damage scattering imaging theory is investigated to obtain surface damage of optical components by a scatter imaging system.Finally,according to the system design,the principle experimental device is built and the subsurface damage of the optical glass is collected and analyzed.The phase correlation algorithm combined with the guide rail information is used to reduce the requirements on the overlapping area of the image,improve the system collection efficiency and reduce the fluorescence quenching effect.The registration accuracy is improved to sub-pixel by the extended phase correlation algorithm of local up-sampling,and the subsurface damage image and surface damage image are registered by Fourier-Mellin algorithm.For the problem of uneven image background brightness caused by the fluorescence quenching effect,the background noise is removed by a non-quadratic minimization polynomial fitting method.The information of subsurface damage points is statistically analyzed by chain code,and the data analysis of subsurface damage is realized.