Borescope

A borescope is an optical device used for inspection work, because of its ability to inspect areas that hard to reach, or even totally inaccessible by other means. The rigid borescope consists of a rigid tube with an eyepiece on one end, an objective lens on the other linked together by a relay optical system in between.

Rigid borecopes have some pretty good advantages compared to the flexible one. Although it’s not that flexible, generally it’s much cheaper and provides better image. Those advantages make rigid borescopes the perfect tool for specific tasks, like inspecting automotive cylinders, fuel injectors, hydraulic manifold bodies and gunsmithing.

Some enhancements can be applied to a rigid borescope. It could be fitted with a magnifying device to illuminate the work being inspected, usually illumination fibers are contained in the insertion tube of the borescope. The eyepiece may be fitted with a coupler lens to allow the borescope to be used with imaging devices such as a video or CCD camera.

Nevertheless, there is one disadvantage that must be taken into account. Unlike fibrescopes, rigid borescopes have the limitation that access to what is to be viewed is a straight line. So, you can’t use it to access cavities which are around a bend, such as a combustion chamber or "Burner Cans".

When buying a rigid borescope, the parameters to consider are image clarity and access. The general rule here is that the largest rigid borescope that will fit the hole, will give the best image. So, the larger the boresope, the better the image will be, but still it must fit the hole. The best thing is to try it. If you need to see into very small holes and relatively large ones, it is usually best to optimize for each, by using two borescopes. The relay optics in rigid borescopes are one of three 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 borecope 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.

When it comes down to choosing a rigid or a flexible borescopes, you must remember the following rule. Rigid borescopes give higher quality images, they are easier to use and are less expensive than flexible scopes of similar quality. Hence, always choose a rigid borescope unless the rigidity is a problem.

Upper Endoscopy | Borescope Lens | Camera Lens | Gradient Lens | Optical Lens | Rod Lens |