Inspecting high-reflective objects from flat surfaces is naturally vigorous to accomplish with ring illumination. Whenever it hits the surface, light reflects away from the lens, and as a result, it forms a dark image. So, the led coaxial light source is highly beneficial for viewing the targets and producing a bright picture. For matching the optical axis of lighting and lens, this type of lighting usually uses a half-mirror.
LED lighting is still an emerging technology with improving efficiency, ever-increasing intensities, and becoming inexpensive. Ultraviolet LED lighting is in the expanding market, making uses both reasonable as well as possible. The other technologies still are there, but the led coaxial light source is gaining much more importance.
Here are some of the factors and types of coaxial lighting.
Important factors affecting lighting
An illumination solution needs to be selected to produce an image that best suits machine vision software that reveals the particular defects or features of the camera. Some elements affect the lighting, such as:
- The Angle of illumination affects the lighting.
- Backlighting is another factor that affects lighting.
- The wavelength of light affects the intensity of lighting
- Light propagation and geometry
- Surface and geometry of the object
- Illumination control
- Illumination affects the lighting on a large scale.
- Standard coaxial illumination
- Illumination for use on reflective surfaces.
Types of coaxial illumination
Here are three types of illumination that effect the quality of an image.
Standard coaxial illumination
This technique helps illuminate reflective surfaces. A semi-transparent mirror or a beam splitter or is appropriate to divert the light from a light source immovable on the side (coaxial) so that it is estimated almost parallel to the optical axes of the camera onto the object.
Moreover, the technique of coaxial illumination is perfectly suitable to plain reflective, ‘mirror-like objects with no (or very little) outline or any sides which have diffuse backgrounds. Examples include reflective labels, PCB inspection, polished silicon wafers, or print inspection.
Advanced coaxial illumination
These types of illumination are for homogeneous illumination of uneven surfaces. The advanced coaxial illumination uses an extra reflection chamber. The light is not released directly from the light source onto the object through the semi-transparent mirror, carrying a much more homogeneous illumination.
Collimated coaxial illumination
Collimated light source beneficial for the detection of shallow flaws on flat, reflective objects. This type of illumination collimated light when rays of light in a beam are parallel. Consuming light from a collimated light source is especially beneficial for detecting surface flaws and dents on flat, reflective objects.
Any surface features such as depressions or bumps reflect the light out of the lens’s field of view and appear as dark areas on the image. It is explained with the dented coin cell shows this consequence.
Though Proper illumination is the responsible factor between the success and failure of illumination, an extensive range of yields and techniques are settled for overcoming various lighting obstacles. The deformations, grooves, colors, and areas represent the difficulties according to different applications.