The quality of vision results, in Machine Vision as well as in Microscopy, strongly depends on the quality of lighting. By using different lighting techniques, different features of the object can be made visible.
Lighting and Optics are 80% of most machine vision applications.” “If you can’t see it in the monitor then the vision system can’t see it either.” (Society of Mechanical Engineers/Machine Vision Association)
The purpose of the illumination is to enhance the contrast of the object in a way that the desired feature is detectable by the MV system. On the basis of interaction of the light with the surface of the object a detectable contrast is created. Important is which portion of the light is absorbed and which is reflected or transmitted back to the camera.
The most common lighting techniques are described following: