Close Visual inspection, with or without optical aids, is the most primitive method of NON-Destructive Testing (NDT). Surface-breaking defects can be detected by a thourgh close visual inspection (CVI).
Optical aids are ofen used including low-power magnifiers, microscopes, telescopes and also specialised devices such as boroscopes, endoscopes and other fibre-optic devices for the inspection of restricted access areas implementation of television camera systems can also be used. The success of visual inspection depends on the surface condition and the lighting arrangements. Surface preparation such as cleaning and etching is often used.