The ring light source uses high-density LED arrangement, 360° irradiation, eliminating shadows; The middle hole makes the light source fit perfectly with the lens; Multi-angle optional, adapt to different working distance; Optional diffuser plate to evenly diffuse light. Application range of character, screen printing recognition; Barcode, two-dimensional code reading; Product size measurement; Product damage and defect detection; Foreign object identification on wafer; Detection of foreign body in liquid, etc.