This example shows how to inspect the concentricity of both the core and the cladding in a cross-section of optical fiber. Concentricity is a measure of how centered the core is within the cladding.
First, the example uses the Blob Analysis block to determine the centroid of the cladding. It uses this centroid to find a point on the cladding's outer boundary. Using this as a starting point, the Trace Boundaries block defines the cladding's outer boundary. Then the example uses these boundary points to compute the cladding's center and radius using a least-square, circle-fitting algorithm. If the distance between the cladding's centroid and the center of its outer boundary is within a certain tolerance, the fiber optic cable is in acceptable condition.
The following figure shows examples of optical fibers with good and bad concentricity:
The following figure shows the Concentricity Inspection example model:
Concentricity Inspection Results
In the Results window, you can see that the example marked the cladding's centroid with a red '+'. It marked the center of the cladding's outer boundary with a green '*'. When the distance between these two markers is within an acceptable tolerance, the example labels the cross-section of fiber optic cable "Concentricity: Good". Otherwise, it labels it "Concentricity: Bad". The example also displays the distance, in pixels, between the cladding's centroid and the center of the cladding's outer boundary.