Last Updated: August 4, 2022
In your fiber optic cable assembly facility, when an operator visually inspects one of your connectors – and sees a defect on a fiber – will the operator define it as a defect or call it a scratch? It’s a bit of a judgment call as it depends on the aspect ratio. If it’s deemed a scratch, its width must be measured and this can vary from end to end. Also, the operator must determine if the scratch goes across the core of the fiber. Will he or she determine that the scratch is sufficiently minor, then pass the connector? Finally, would a different operator arrive at the same set of measurements and pass – or fail – that same connector?
If you’re using an ordinary optical microscope for your inspection process, you need quite a high magnification – something like 200x or 400x – to check whether fibers are in good condition and to see (and measure) defects and scratches. The task is challenging for an inexperienced operator. Because you can only see one fiber at a time, you have to scroll to look at the first fiber, then the next, and so forth. If the connector has 24 fibers, it takes time to look at each fiber and determine a pass/fail result for the connector. Visual inspection is further complicated by inconsistent skill levels and the eyesight of different operators.
Visual inspection is made easier with an automated fiberscope. This instrument images and processes each fiber based on a set of rules and criteria that meet IEC standards (or your custom test parameters). At its essence, the automated fiberscope is a digital microscope that views connectors, looks for defects, and measures defects.
The FastMT fiberscope manufactured by FiberQA is designed to be used on MT ferrules, which generally have rows of 12 fibers in one connector (12, 24, 36 and so forth, up to 72 fibers). This instrument cleverly locates and identifies the fibers, organizes the images, and displays a live view of all ferrules on the monitor at the same time. You might call it “intelligent vision.” Since all fibers are shown at once, it’s easy to determine if the connector needs additional cleaning before analysis.
Next, you push a button to process the image. The FastMT fiberscope identifies defects on each fiber using sophisticated machine-vision algorithms then compares this with a set of rules. Here’s an example rule: “There can be no scratches greater than 3 microns within the core zone of each fiber.” The fiberscope lists all defects with measurements and provides a pass/fail result for each fiber in the connector. If any fibers fail, then the connector as a whole fails.
As a side note, FiberQA recently released a new software version for its FastMT fiberscope models FMT-080, FMT-200, and FMT-400.
This significant software upgrade offers a variety of robust features to customize your testing process.
Automated fiberscope versus manual inspection with an optical microscope
“Automation” is the holy grail of the fiber optic industry, and this certainly applies to cable assembly facilities. Since our industry is so labor intensive, whenever you have an instrument that can save labor and time, you can potentially streamline your process and save expenses. The FastMT fiberscope replaces a manual visual inspection process with automation to image and process MT ferrules. Once this fiberscope is set up for your particular fiber optic cable assembly product, the operator just plugs in the connector. The instrument checks for defects, then provides pass/fail results (with either a green light or red light). Next, the operator simply packages the good connectors and ships them.
While different cable assembly houses discover different benefits when using an automated fiberscope, Fiber Optic Center customers report 3 key benefits of integrating the FastMT into their testing process: objective versus subjective measurements, continual process improvement, and proof of documentation.
- Objective versus subjective measurements – Most of my customers tell me they want their defect test process to be consistent. They want a reliable instrument that will make an objective measurement rather than depend on different operators with subjective points of view. When using the FastMT, you still need trained operators to use this equipment. However, you may not need as many highly skilled operators with a practiced eye who can quickly see and consistently measure defects and scratches.
- Continual process improvement – In every manufacturing process, it’s important to keep your finger on the pulse. For visual inspection, I recommend you keep trend statistics on a variety of parameters. For example, perhaps there is an increasing occurrence of scratches, even though they are below the threshold stated in the specification and the connectors are still passing. The FastMT fiberscope stores all measurement data. You can address the scope of data collection that meets your needs; it’s very flexible in that respect. In our example, seeing a trend develop –an increasing number of fine scratches – could encourage you to investigate and refine your polishing process. It’s helpful to be able to quantify a degradation in end-face quality before it becomes an issue.
- Proof of documentation – Manual observation cannot provide proof that a connector is in good condition, other than an operator’s checkmark indicating that it was inspected and passed the specification. What if your end customer reports that a connector is heavily scratched and unusable? Including a photo showing how it looked during the visual test with a listing of test measurements can certainly be useful. The FastMT’s reporting feature is customizable, allowing the operator to choose the file type (MS Word, PDF, or HTML), the information to include, and when to automate a printout (e.g., pass only, fail only, or both). The ability to produce documentation for every connector can be extremely useful proof against possible claims from end customers.
If there was a magic machine where you could pour in fiber, epoxy, ferrules, and connectors and – with the push of a button – get finished fiber optic cables, everyone would be delighted. Until someone invents that magic machine, it’s useful to incorporate automation such as the FastMT fiberscope into your visual test process. As noted above, advantages include objective measurements, trend analysis, and helpful documentation.
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