The Borescope is an optical device consisting of a rigid or flexible tube with an eyepiece on one end, an objective lens on the other linked together by a relay optical system in between. In some instances it also includes optical fiber for illumination. The image is captured by the objective lens and magnified by de eyepiece like a microscope.

Borescopes are used for visual inspection work where the area to be inspected is inaccessible by other means. Borescopes are mostly used in nondestructive testing techniques for recognizing defects or imperfections. Similar devices for use inside the human body are referred to as endoscopes.

They are commonly used in the visual inspection of:

• aircraft engines
• aeroderivative industrial gas turbines
• gas and steam turbines
• diesel engines, and automotive and truck engines.
• building inspection
• weapon inspection