Boroscopes or Bore Scopes

A boroscope is an optical device consisting of a rigid or flexible tube used for inspection work where the area to be inspected is inaccessible by other means. The borescope is popular in the areospace, automotive, fuel systems and precision shooting industries. However the borescope is a useful tool for any industry where inspection using the human eye alone is prohibitive.

Rigid Borescopes

Image of a borescope borescope image borescope image borescope image close up of borescope image

Rigid boroscopes are similar to a fiberscope, however they are not flexible and they tend to be much cheaper, providing a superior image. Rigid boroscopes are therefore better suited to certain tasks including amongst others, inspecting automotive cylinders , hydraulic manifold bodies, fuel injectors and gunsmithing. Rigid or flexible boroscopes can be fitted with a magnifying device and a way to illuminate the work being inspected, usually illumination fibers are contained in the insertion tube of the boroscope. The eyepiece may also be fitted with a coupler lens to allow the borescope to be used with imaging devices such as a video, CCD camera or SLR cameras enabling borescope photography.

Light is passed along the borescope between a series of lenses positioned at regular intervals. The quality of these lenses is what determines the quality of the final image.

Flexible Borescopes

Rigid borescopes on the whole provide a superior image at lower cost compared to a flexible borescope, but have the limitation that access to what is to be viewed is a straight line. A flexible borescope can be used to access cavities which are around a bend, such as a combustion chamber, in order to view the condition of the compressed air inlets, turbine blades and seals without disassembling the engine.

Not too disimilar to the endoscope or cystoscope, the flexible borescope disposes of the lens relay of the rigid borescope in favor of fibre-optics. A bundle of fibre-optics is used to pass the image. The more fibres, the higher the image's output resolution and also the likely cost of the scope. With this technique of using fibre optics, it's crucial that the fibres maintain their relative positions at each end of the scope, otherwise the image becomes scrambled.

Micro Borescopes

Borescope technology has advanced in recent years and has produced borescopes today that have a diameter of under 1mm. These flexible micro-borescopes are perfect for getting up close to precision machinery and electronics which before would have required a time consuming dismantle.

Which is the best type of Borescope?

Criteria for selecting a borescope is usually image clarity and access. For similar quality instruments, the largest rigid borescope that will fit the hole, will give the best image. Relay optics in rigid borescopes can be of 3 basic types, Hopkins rod lenses, achromatic doublets and gradient index rod lenses. For large diameter borescopes, the achromatic doublet relays work quite well, but as the diameter of the borescope tube gets smaller (less than about 4 millimeters) the Hopkins rod lens and gradient index rod lens designs provide superior images. For very small rigid borescopes, the gradient index lens relays are better.

Borescope Quality

Flexible borescopes can suffer from pixelation and pixel cross talk due to the fiber image guide used in the relay. Image quality varies widely among different models of flexible borescopes depending on the number of fibers and construction used in the fiber image guide. 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.This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Borescope".

Provision Borescopes - Make / Manufacturer

Provision borescopes are a perfect entry level borecope brand. Specialising in low cost bore inspection equipment and borescope kits and accessories which still offer good build quality and visuals. These scopes are excellent options for those users who don't need high end specifications but would benefit from a low cost solution to ad to their tool kit. Ideal for a plumber, pest controller or mechanical engineer who require the scope for occasional work. Provision have a good selection of flexible fiber-optic borescopes and accessories.

Atlantis borescope inspection - July 2009 News

A borescope came to the rescue last month on the space shuttle Atlantis. Apparently a work light knob became wedged between the pressure pane on Atlantis' pilot window and the dashboard panel. A borescope was used to inspect what damage had been caused. More of this here...