Fibre optic air hole size detection

A high tech optical fibre has air holes running down it. Gas is passed through the holes to change the temperature of the fibre to optimise it for different frequencies of light. For quality control purposes, the size of the air holes may need to be measured from time to time. This may be done by viewing a cross section of the fibre under a high resolution microscope. The image may look like this, where the dark circles are the air holes.

Passing this through a simple colour threshholding filter gives a similar picture like this.

Separating the disjoint blobs and counting their area in pixels gives a result like this.

Some blobs are joined together, which is a slight issue that would likely be solved when using our lens. This image was taken with a standard 100x lens. Blobs are sorted by size, starting with the largest. This is only a demonstration to show that some of the quality control process could be automated, e.g. finding air holes which are out of specification. In practice, better image analysis would need to be performed, but this little demonstration shows the feasibility.

Here’s the result displayed in another form.

A high tech optical fibre has air holes running down it. Gas is passed through the holes to change the temperature of the fibre to optimise it for different frequencies of light. For quality control purposes, the size of the air holes may need to be measured from time to…

A high tech optical fibre has air holes running down it. Gas is passed through the holes to change the temperature of the fibre to optimise it for different frequencies of light. For quality control purposes, the size of the air holes may need to be measured from time to…