The procedures in this document describe basic inspection techniques and processes of cleaning for fiber optic cables, bulkheads, and adapters used in fiber optic connections. The primary reason for fiber inspection is to ensure that the connectors are free of any defects, damage, or debris that would prevent sufficient transmission of light when mated. This Applications Engineering Note (AEN 135) explains and recommends standard measurement methods for characterizing optical fiber system performance. It is important that every fiber connector be inspected and cleaned prior to mating. Every endface shou surface area than a single fiber connector.