A boroscope is an optical device consisting of a rigid or flexible tube with an eye piece and an objective lens on the other linked together by a relay optical system in between.
Fiber optics Inspection (Boroscopy) is a remote visual examination technique/tool for determining the presence of internal defects including internalcracks, intensity of corrosion or erosion, oxidation or internal deposits, degree of damage, pitting and presence of foreign objects etc.in any directly inaccessible area of component through Inspection hole, tube cutting opening and its other integral parts etc.
The optical system in some instances is surrounded by optical fibers used for illumination n of the remote object .
An internal image of the illuminated object is formed by the objective lens and magnified by the eye piece which presence it too the viewers eye. Rigid or flexible borescope may be fitted with an imaging or video device.