Borescope
This article relies largely or entirely on a single source. (November 2014) |
A borescope (occasionally called a boroscope, though this spelling is nonstandard) is an
Rigid or flexible borescopes may be externally linked to a photography or videography device. For medical use, similar instruments are called endoscopes.
Uses
Borescopes are used for visual inspection work where the target area is inaccessible by other means, or where accessibility may require destructive, time consuming and/or expensive dismounting activities. Similar devices for use inside the human body are referred to as endoscopes. Borescopes are mostly used in nondestructive testing techniques for recognizing defects or imperfections.
Borescopes are commonly used in the visual inspection of aircraft engines, aeroderivative industrial gas turbines, steam turbines, diesel engines, and automotive and truck engines. Gas and steam turbines require particular attention because of safety and maintenance requirements. Borescope inspection of engines can be used to prevent unnecessary maintenance, which can become extremely costly for large turbines. They are also used in manufacturing of machined or cast parts to inspect critical interior surfaces for burrs, surface finish or complete through-holes. Other common uses include forensic applications in law enforcement and building inspection, and in
Flexible versus rigid
The traditional flexible borescope includes a bundle of optical fibers which divide the image into pixels. It is also known as a fiberscope and can be used to access cavities which are around a bend, such as a combustion chamber or "burner can", in order to view the condition of the compressed air inlets, turbine blades and seals without disassembling the engine. Traditional flexible borescopes suffer from pixelation and pixel crosstalk due to the fiber image guide. Image quality varies widely among different models of flexible borescopes depending on the number of fibers and construction used in the fiber image guide. Some high-end borescopes offer a "visual grid" on image captures to assist in evaluating the size of any area with a problem. For flexible borescopes, articulation mechanism components, range of articulation, field of view and angles of view of the objective lens are also important. Fiber content in the flexible relay is also critical to provide the highest possible resolution to the viewer. Minimal quantity is 10,000 pixels while the best images are obtained with higher numbers of fibers in the 15,000 to 22,000 range for the larger diameter borescopes. The ability to control the light at the end of the insertion tube allows the borescope user to make adjustments that can greatly improve the clarity of video or still images.
Rigid borescopes are similar to fiberscopes but generally provide a superior image at lower cost compared to a flexible borescope. Rigid borescopes have the limitation that access to what is to be viewed must be in a straight line. Rigid borescopes are therefore better suited to certain tasks such as inspecting automotive cylinders, fuel injectors and hydraulic manifold bodies, and
Video borescopes
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References
- ^ Popular Mechanics, Dec 45, page 50.