Algorithm of focal spot reconstruction for laser measurement using the schlieren method

The far-field distribution of lasers is an important parameter for measuring beam quality. To overcome the insufficiencies of the CCD Camera dynamic range when measuring the far-field focal spot, the schlieren method was used to measure the focal spot far-field spatial distribution. Focal spot reconstruction was achieved after gray image matching, calculating the center, and image merging of the main lobe and side lobe. In this study, we used an algorithm based on the optimal arc to obtain the center for the side lobe images by fitting the circle center to improve the accuracy of the focal spot reconstruction. The results showed that the schlieren method of measuring the focal spot reconstruction algorithm could effectively, accurately and completely obtain the far-field focal spot.