Machine vision is a technology used to provide imaging-based automatic inspection and analysis. Line scan technology can capture images of wide objects with a single pass. Using area scan techniques, a series of images have to be captured and stitched together to get the complete image.
A line-scan camera traditionally has a single row of pixel sensors, instead of a matrix of them. The lines are continuously fed to a computer that joins them to each other and makes an image.
So for certain applications, line-scan systems have specific advantages over area scan systems. For example, inspecting cylindrical parts may require multiple area scan cameras to cover the entire part surface. However, rotating the part in front of a single line scan camera captures the entire surface by unwrapping the image.
Line-scan Vision Inspection for wide and long components
Line scan is an excellent way of imaging cylindrical components. A line scan camera records the same position across the whole cylinder and as the cylinder rotates an ‘unwrapped’ image of the entire surface is generated without the distortion that would result from imaging a curved surface with an area scan camera.
This technique allows the inspection of surface for defects such as dents, pits, scratches, holes, etc.
It is also possible to unwrap labels, allowing the reading of codes and human readable characters.
Other typical Line Scan Machine Vision applications are
- Inspection of web and fabric
- Inspection of products on a conveyor belt
- Inspection of very large surfaces were the Line scan camera is moved about the surface
Because of the movement in these applications, timing and alignment needs to be attended to. Also, line scan cameras require a high level of illumination, especially when compared to “normal” area scan.