Particularly within the consumer electronic industry, opaque matt plastics are widely used as casing for materials. This can make it imperative that the finish is flawless, as the consumer is unforgiving.
Opaque matt plastics present a unique challenge when performing quality control with machine vision. Many of the issues in other cases are due to the art or product reflecting too much light, making the image difficult for the machine vision system to capture.
In this particular instance the reverse is true.
The matt opacity absorbs light, which is, of course, the point. However, this means that there is little light available for the camera’s sensor to capture the necessary image, making it difficult to determine if the product is free from defects.
The obvious answer is to bathe the object in light. Doing this from a coaxial point of view, though, simply leads to a bright image with no definite features.
Instead, by angling the lighting you can cause the surface features to be picked out, allowing the machine vision system to capture any surface defects. To create this kind of lighting field, use LED bar lights and, possibly, angle brackets to create either square or parallel lighting which can then be adjusted in intensity to create the ideal amount of radiance for an accurate image.