Fiber Optic Cleaning and Inspection Flashcards
7 cards from real CFOT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fiber Optic Cleaning and Inspection flashcards as text
What does the industry best practice principle 'inspect before you connect' require?
Answer: Visually inspect every connector end-face for contamination before mating
Inspecting every end-face before mating is a mandatory step that catches contamination which could cause signal loss or permanent damage if connectors were mated without inspection.
Why must technicians never look directly into the end of an active fiber optic cable or connector?
Answer: Infrared laser light can cause permanent eye damage with no visible warning
Fiber optic systems use 850 nm, 1310 nm, or 1550 nm infrared lasers that are invisible yet powerful enough to permanently damage retinal cells without any sensation of pain.
What does a reel-type cassette cleaner use to clean fiber optic connector end-faces?
Answer: Pre-moistened and dry cleaning fabric that advances to a fresh section each use
Cassette cleaners use a reel of cleaning fabric that automatically advances to a fresh section with each use, providing reliable wet-then-dry cleaning in a single stroke.
What end-face geometry parameters measured by an interferometer directly affect connector return loss performance?
Answer: Fiber height (protrusion or undercut) and radius of curvature
Interferometers measure fiber protrusion/undercut and radius of curvature to verify proper physical contact geometry, which determines how well end-faces mate and their return loss performance.
When inspecting a fiber end-face under a microscope, what appearance distinguishes a scratch from surface contamination?
Answer: Scratches appear as linear marks that persist after thorough cleaning attempts
Scratches are physical damage to the glass and appear as persistent linear marks that cannot be removed by any cleaning method, unlike contamination which is removed by cleaning.
How often should fiber optic connectors be inspected and cleaned in an active network?
Answer: Every time they are disconnected and before every reconnection
Best practice requires inspection and cleaning every time a connector is disconnected because handling and air exposure immediately introduce contamination.
Why can even sub-micron particles cause measurable insertion loss on a single-mode fiber connector end-face?
Answer: The single-mode core is only ~9 μm, so even tiny particles block a significant portion of the light path
Because the single-mode core diameter is approximately 9 μm, a sub-micron particle in Zone A can block a meaningful fraction of the guided light and cause measurable signal loss.