Application of diffractive elements for improving the efficiency of systems for cylindrical surface inspection

An improved method of structural lighting for increasing the efficiency of inspection of the cylindrical object surface appearance is considered. The method is based on using a diffractive optical element to reduce the amount of recorded data due to illuminating the test object at an angle to the image recording plane, which is normal to the inspected surface. Implementation of the proposed method implies the use of several identical channels. For this reason, one channel is considered in the present study. Calculations of diffractive elements, a description of the experimental setup, and results of experiments aimed at determining the depth of surface defects on objects simulating fuel pellets and fuel elements are presented. Implementation of the investigated method with defect depth determination in industrial systems of inspection of fuel pellets and fuel elements is expected to improve the quality of the fuel for atomic power stations.