Dust - just because you can’t see it doesn’t mean it’s not there.
A 1-micrometer dust particle on a single-mode core can block up to 1% of the light (a 0.05dB loss). The only way to know it’s clean is to inspect it before you connect it. And if it’s dirty, it needs to be cleaned with the right tools or you might just make it worse. Know it’s clean with Fluke Networks cleaning and inspection tools.
Check the video below on how to visually inspect fibre optic cables before installing and cleaning to ensure signal Integrity:
If you would like to know more, receive a datasheet or a quotation please get in touch here.