Detection Of Internal Defects In Optical Element Based On Line Source Scanning

Optical components are widely used in ICF laser driver. If there are internal defects in the chunk glass, which is used to produce optical components, such as pocks and bubbles, the performance of the optical system might be influenced, and it even cause damage to the optical element. Therefore, it has vital significance to study a method to detect optical element internal defects automatically.The topic is presented in this situation. After analyzing the deficiency of the traditional methods, such as low detection efficiency, limited sample size and leakiness, the simulation of the distribution of scattering light intensity is studied by using Matlab software according to the Mie scattering theory. Then, several probable schemes of internal defects detection are put forward according to the simulation results. On the basis of analyzing the advantages and disadvantages of the schemes, a method to detect internal pocks and bubbles of optical elements based on laser line source scanning is proposed. In dark field environment, a laser line source is used to illuminate from one side of the glass under test, a high-resolution CCD camera is used to take pictures in front of the glass sample. Full aperture images which contain information of defects are acquired through image stitching and accurate scanning method is proposed to get precise z-coordinate. Finally, the spatial distribution of internal defects and granularity statistics are acquired, which descript the characteristic information of internal defects quantificationally.In order to verify the reliability of this method, the result of the experiment is used to compare with that of the microscope measurement. According to the comparison result, the proposed detection of defects in optics based on laser line source scanning has a relative aberration smaller than 2%, which means the approach is accurate and credible. The spatial distribution of internal defects and granularity statistics can be realized by the method. Finally, the prospects of scale features of defects are put forward.