You can also position a light source to provide front illumination from only one direction. At a high angle, such directional lighting lets an inspection system measure shadows and calculate the heights of components. Use this technique to find surface irregularities such as burrs. Employ this lighting technique to shine light directly into a hole or a small subassembly. Because this technique provides uniform illumination across your field of view, it can reduce shadows and some glinting.
Light can also illuminate a product from behind.
Back lighting a translucent PCB lets you locate components and find holes unoccupied by a lead or solder. You can choose from six types of lighting techniques to best illuminate the product you want to inspect. Some inspection systems may use a combination of the techniques above. Typically, inspection systems use back lighting to highlight cracks, particles, and air bubbles in translucent or transparent parts. Put Lighting to Work Now that you better understand the choices of lighting and lighting techniques available to you, three brief examples will show you how to put lighting techniques into practice.