There are currently three methods of looking inside a fiber optic connector: (1) Non-destructive X-ray (2) Lossless sonar (3) Destructive cross section These methods help engineers determine the causes and effects of fiber optic connector failures and monitor the connector assembly. There are currently three methods of looking inside a fiber optic connector: (1) Non-destructive X-ray (2) Lossless sonar (3) Destructive cross section These methods help engineers determine the causes and effects of fiber optic connector failures and monitor the connector assembly. Researchers The University of Southampton, with financial support from National Grid Transco, have developed an X-ray imaging technique that allows non-destructive investigation of high voltage cable joints. Defects such as thinning of the semiconducting sheaths, or of the bulk insulation, can be. A structured testing methodology allows engineers and procurement teams to confirm that delivered fiber cables comply with design specifications and international standards. Corning recommends that all fiber optic systems be tested to a minimum set. Fiber Optic Testing Testing is used to evaluate the performance of fiber optic components, cable plants and systems.