In automated optical inspection (AOI), cameras and algorithms get most of the attention. But image quality starts with light. By the Hecho Technology technical team, based on our experience in industrial fiber optic illumination projects. What Goes Wrong When Illumination Is Poor? Shadow interference. Solder joints and components on a PCB are three-dimensional. Single-direction lighting always casts shadows. The algorithm can‘t distinguish shadows from defects — false positives and missed defects follow. In our work helping customers optimize AOI illumination, we’ve seen defect detection rates improve from 79% to 94.7% after optimizing the light field, with false detection rates dropping from 36% to 9%. Glare from reflective surfaces. Metal pads, wafer surfaces, and glass substrates produce specular reflections under standard lighting. Bright spots in the image wipe out defect information underneath. Non-uniform illumination. Bright areas look normal, dark areas look like defects. The algorithm struggles to make consistent judgments. How Fiber Optic Illumination Solves These Problems Cold light. Hecho‘s S5000 series LED cold light sources use a light-heat separation design — heat stays at the source, the output end stays cool. Critical for heat-sensitive wafers and precision components. S5000D Continuous output. Hecho’s ring and linear fiber optic light guide bundles use continuous fiber arrangement — no gaps, no bright-dark alternation. Superior uniformity compared to discrete LED arrays. Flexible light shaping. Swap the fiber bundle to change the light pattern — linear fiber for line scan cameras, ring fiber for shadow-free illumination, coaxial fiber for reflective surfaces. All customizable from Hecho. Source-to-workspace separation. Fiber delivers light to the inspection point while the source stays remotely mounted — saving valuable space inside the AOI machine. Typical Applications PCB/FPC inspection: Linear fiber with line scan cameras for high-speed continuous scanning. Ring fiber for solder joint inspection, eliminating shadows. Semiconductor wafer inspection: Coaxial illumination for reflective surfaces. Dark-field ring light makes micro-scratches and particles stand out against a dark background. Reflective surfaces: Metal parts, glass lenses — coaxial fiber illumination suppresses glare and makes defects clearly visible. Hecho Technology has years of experience in AOI fiber optic illumination, offering linear, ring, coaxial, and area fiber optic light guides in plastic, glass, and quartz — with full customization support. For selection assistance, contact our technical team.