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ND/Yag Welder Fiber Optic Delivery failures

ND/Yag Welder Fiber Optic Delivery failures

ND/Yag Welder Fiber Optic Delivery failures

A company I work with keeps burning up Fiber Optic Cables. They got me through one of their employees who I used to work with at another Job Shop. This is the only Fiber Optic system I have had to work on, so not sure of what is common in failures. System is a Lumonics Luxstar 50. The Cables keep failing at the output, you can see the lens output optic toast, then when you disassemble it, cable is fried. Here are the Facts I know:

1. Currently they used uncoated windows to protect the focus lens (I believe Focal length is about 100mm).
2. they are supposedly not welding directly down, but I have some doubts.
3. Laser is at about 90% tuned even with new lamps and output and rear optics. Rod is old, but looks good.
4. Cable has only failed at output.
5. they are welding medical instruments used in stitching.

To me the possibilities are:

1. Poorly made window that is reflecting some of the energy back
2. they are not at enough of an angle to prevent reflections back.
3. lenses or external optics causing reflections back.
4. old cables, even if unused inherently fail (do fibers get brittle over time?

Maybe my inexperience has me overlooking something else, here is what I am assuming:

1. If failure was caused by the Laser itself, failure would be on the input unless cable isn't rated for this power (which should not be the case).
2. once light makes it to the input of the cable, it should make it to the output in same state it went in, that a cable itself cant de-collimate the beam. That there is no way for a beam to focus inside the fiber.
3. This problem has to be from between the output of the cable and the process.

they have gone through 3 cables in 6 months, last cable lasted only a couple weeks. I havent seen the failure because I do not work there, i only get called after they are down.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

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