Machine vision requires good image quality to make accurate and repeatable measurements. A good image shows the features of interest with sufficient contrast and signal-to-noise to differentiate them from other surrounding features and background. There are fundamental lighting principles that influence the overall image quality:
Geometry
The geometry relates to the spatial relationship between the workpiece, light, and camera. The image produced depends on the direction and angle of illumination to the workpiece and the camera.
Workpiece Characteristics
The workpiece's unique characteristics influence how light interacts with it. These characteristics include color, surface texture, shape, and reflectivity. The inspected features and the rest of the workpiece often have different qualities, and both are important considerations when designing a lighting solution.
Form Factor
Machine vision lights are available in various form factors differentiated by lighting configuration, shape, and output intensity. These determine how the light projects onto the sample. Different levels of uniformity, degree of collimation, and structured light patterns can affect an image. The light intensity must also be sufficient to overcome any unwanted contributions from ambient light.