What Is a Borescope?

A Borescope is an instrument used to inspect the inside of a structure through a small hole.

Industrial Borescopes

Industrial borescopes allow for remote visual inspections (RVI) in areas where it is difficult or impossible for the human eye to see into directly. However, the term “borescope” has become a generic term to describe four types of products/technologies used for internal inspections. While there are key differences between these inspection cameras, the earliest RVI product was called a “borescope” – the name stuck even as new technologies were developed.

Borescopes serve a multitude of applications including aviation, aerospace, sanitation, automotive, weaponry, metal casting, law enforcement, electronics, refining, and power generation. In order to accommodate a variety of industries, borescopes vary in length, diameter, and functionality. To answer the question “What is a Borescope?”, let’s take an in-depth look at each type of borescope.

Rigid Borescopes


Remote visual inspection has been around for approximately 80 years. In World War II, the earliest models of rigid borescopes were used for interior bore examinations in large guns.

Rigid borescopes, still used for gun barrel or borehole inspections today, are ideal for applications that require only straight-line access to an inspection target. Rigid borescopes are simple tubes shaped like long, thin telescopes that use a lens system to send an image to a relay lens from the object to be viewed in real-time. This is accomplished with an eyepiece on the proximal (near) end and an angled mirror pointed toward an opening in the tube on the distal (far) end.

While rigid scopes have excellent image quality, they are limited to only accessing internal parts that can be viewed in a direct, straight line. In addition to gun barrels, they are often the best option for very small bore, straight pipe, or small part inspection, but do not work well for viewing inside objects with irregular internal cavities.

Semi-Rigid Scopes

A step up from rigid borescopes, semi-rigid borescopes are bendable and best for confined spaces that do not offer room for articulation. Semi-Rigid borescopes are more forgiving and durable than the rigid borescope, which is mainly due to technological progressions and their ability to bend. However, they are known for having a poorer image quality than other types of borescopes, which may deter companies requiring high-resolution image viewing.

Some of these semi-rigid scopes are also classified as fiberscopes, which are offered in semi-rigid and articulating forms. The image will suffer from pixelation; the viewing screen and photos will display tiny black dots caused by the broken pixels. Once the strands start to break down, there is no repairing them and the entire unit will have to be replaced.

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Over 10 Years Experience

RF System Lab was established in 2008 with the goal of bringing affordable, high-quality video borescopes to the market.

The best way to ensure the VJ-3 mechanical articulating borescope is the right choice for your company is to try the borescope for free at your facility.



Fiberscopes arrived on the market about 35 years ago with the development of fiber optics, which are extremely thin strands of glass. Fiberscopes bundle together anywhere from 3,000 to perhaps 30,000 or more fiber strands. A fiberscope uses these fibers to transmit an image from the lens closest to the object being viewed through the bundle to a relay lens. The image captured by the lens can be viewed directly through an eyepiece, or the eyepiece can be attached to a camera that displays the image on a monitor.

One of the main advantages of fiberscopes over rigid borescopes is that fiberscopes are flexible and can be used for inspections in which straight-line access is not available. While some fiberscopes are also classified as “semi-rigid”, fiberscopes are also available with articulation. Articulation in a borescope means that the distal two inches or so of the scope’s insertion tube can be pointed in any direction, usually by means of control knobs located at the proximal end. In other words, the first few inches of the inspection tool that get inserted into the object are steerable or “controllable” by mechanisms on the unit that is closest to the inspection technician.

Articulating fiberscopes are the closest option to video borescopes in terms of quality and aptitude. However, there are some downsides to fiberscopes. Many of the low-cost fiberscopes, carried by auto parts stores, for example, use elastic fibers instead of glass fibers. The image quality for these scopes varies among different models depending on the number of fibers. For fiberscopes, transparency of the fibers directly relates to image quality. IE: Looking through a plastic drinking glass would be more difficult than looking through a glass one.

Another disadvantage of fiberscopes is that if any of the fiber strands break from rough articulation or simple overuse, the image will suffer from pixelation; the viewing screen and photos will display tiny black dots caused by the broken pixels. Once the strands start to break down, there is no repairing them and the entire unit will have to be replaced.

Video Borescopes or Videoscopes


Videoscopes, the most recent development in inspection camera technology, are similar to fiberscopes in that that there are both articulating videoscopes and non-articulating videoscopes. The main mechanical difference between videoscopes and fiberscopes is that a videoscope has a micro video camera and light located at the far end of the insertion tube. The camera directly captures the inspection image and electronically carries the video signal down the insertion tube to a video processor and display. This process results in a much higher resolution image quality,