The two sides of the steel side plate are made up of two parts, which are assembled by laser welding. Defects appear near the weld, and some of these defects are smaller than 0.3 mm along the weld beads that is not easy to find.

Due to the previous PCB board glue detection is used in the fluorescent lamp detection, resulting in low efficiency, high missed detection, and unable to carry on data preservation, since the use of the visual system, the customer's problem has been sovling of glue detection.