Processing hollow core fiber images

An apparatus comprising:

• a processor;
• a memory storing instructions that, when executed by the processor, perform a method comprising:
• accessing an image of a hollow core fiber;
• for an edge of a tube of the HCF:
• using brightness of the image to detect points corresponding to the edge;
• fitting an edge model function to detected edge points;
• identifying an outlier point of the detected edge points wherein the outlier point is above a threshold distance from the fitted model;
• removing the outlier point and refitting the model to remaining edge points;
• iteratively identifying and removing subsequent outlier points and refitting the model to remaining edge points until all remaining edge points are inlier points below a final distance threshold from the model;
• fitting the remaining inlier points to a final model;
• and
• using the final model to determine a geometric parameter of the HCF, wherein the geometric parameter is used during at least one of:
• quality control, splicing, fiber drawing.

A method for processing an image of a hollow core fiber, the method comprising:

• accessing an image of a hollow core fiber;
• obtaining a model for a shape of an internal edge and an external edge of a cladding capillary of the HCF by:
• using a gradient of brightness of the image to detect points corresponding to the edge;
• iteratively removing subsequent outlier points and refitting subsequent models until all remaining points are inlier points wherein inlier points are below a threshold distance from a final model;
• using the internal and external edge models to mask the cladding capillary from the image of the HCF;
• obtaining center coordinates and a radius for each microstructure capillary of the HCF by:
• transforming the image using a circle Hough transform;
• determining a center location, radius and accumulator value for a circle detected using the transformed image;
• selecting the circle, wherein the circle corresponds to a microstructure capillary of the HCF;
• determining the thickness of each tubular cladding capillary using conservation of mass;
• and
• wherein the obtained center coordinates, radius, and thickness of each tubular cladding capillary and/or derived parameters and/or edge models are used during at least one of:
• quality control, splicing, fiber drawing.