Borescope: What is it? Parties, Types, Structure, Differences and Uses

It is an optical instrument used in those explorations where the area to be inspected is inaccessible by other means.

Currently, boroscopes are increasingly helpful, used for educational purposes, and used by mechanics, civil engineers, and other professionals who use technology daily.

Some boroscopes are used for differential diagnosis in medicine; these are intended to observe the internal functioning of the human body and are known as endoscopy.

In those visual inspections, physical spaces are not available to carry out an inspection. It is necessary to use instruments that have a small size to access the cavities and that sometimes even allow a turn.

Parts of the borescope

Any borescope or device used to see within tiny spaces or the internal organs of the body has these essential parts:

  • An eyepiece at the end.
  • A lens at the other end.
  • A light source with a fiber optic cable allows the transmission of images from the lens to the eyepiece.

For the configuration of the lens in the lens, the following should be taken into account:

  • Field of view.
  • Speed ​​of the lens
  • Distortion and image quality.

The system’s configuration for the retransmission of the images is conditioned by the permissible diameter of the lens, the length required of the instrument, the allowed decrease in brightness or saturation at the periphery of the image, and the quality of the picture. Image.


The eyepiece selection is usually based on the required magnification and the apparent field of vision, which is comfortable for the eye.

Currently, several types of boroscopes are simple or equipped with image or video devices that provide better resolution.

A video-capable borescope usually uses a camera sensor, a charge-coupled device, or a complementary metal-oxide-semiconductor located at the tip of the borescope.

In this way, it originates an image retransmitted to an external viewing device or monitor.

Types of boroscopes

The visual inspection through borescopes goes back approximately 80 years.

Borescopes can be of three types: rigid, flexible, and semi-rigid.

Rigid Borescope

Rigid boroscopes are comparable to simple tubes shaped like thin telescopes that use a lens system to capture an image and send it to a lens in real-time.

This is achieved by installing an eyepiece at the nearest proximal end and a mirror placed at an angle pointing towards the tube’s opening at the distal end.

A combined lens system is used for the transmission of images.

The angular mirrors achieve that the vision is angular at 0º, 45º, 90º, or higher at 90º.

Boroscopio semirígido

The semirigid borescopes combine elements of rigid boroscopes and flexible borescopes.

They are usually small, less than 1 millimeter in diameter, and use a beam of optical fibers to transmit images housed in a rigid thin cover. They are not designed to be tilted by more than 20 °.

They represented a step forward for rigid boroscopes due to their flexibility. They are a better option for confined spaces that do not offer enough space for articulation.

Some can be classified as fiberscopes and have semi-rigid forms with little articulation.

Boroscopio flexible

Flexible borescopes were introduced to the market about 35 years ago, after the development of fiber optics.

Optical fibers are fragile glass threads in which more than 3,000 fiber strands are grouped.

These fibers transmit the image from the closest lens to the object where the inspection is made to the relay lens.

The image captured by the lens can be observed directly through the eyepiece, or this eyepiece can be connected to a camera that, in turn, displays the image on a monitor.

The joint allows the device inserted in the tube of the endoscope can point or orient in any direction.

I usually use controls located at the closest end and accessible to the technician who performs the inspection, helping this system in real-time perform the inspection with greater precision.

The videoscopes are the most recent development in recognition camera technology.

This camera directly obtains the inspection image and transports the video signal electronically through the insertion tube to the video processor and the screen.

The process provides a better image quality with a much higher resolution without the threat of pixilation in flexible fiberoptic borescopes.

This type of boroscope is used in exploratory examinations in medicine, in non-destructive testing of mechanics for small spaces such as aircraft engines, and engineering is used in the cracks of concrete structures.

Structure of a borescope for medical use

The flexible borescopes used in medicine are composed of a long sheath with a plastic coating, inside which, like any borescope, are the optical fibers responsible for transmitting light, the optical components, and the objective as the also the drivers of the image.

In the flexible borescopes, other separate channels are arranged to carry out the aspiration and pass the irrigation liquid or as a conduit to deliver any instrument.

Generally, the light is fed through the optical fibers present in the mechanism.

With rigid borescopes with high technology, there are three different groups of components of the optical system as image drivers: objective, transmission or inversion system, and ocular lens.


The function of the objective is to generate the image of the area being inspected inside the borescope located at the distal end of the borescope.

The lens can be combined with up to nine different lens types.

The visual directions of 5 °, 12 °, 30 °, 50 °, 70 °, etc., require as a first mechanism of the lens a prism with the appropriate kink. Borescopes with a 0 ° visual direction do not have prisms installed.

The objective and the lenses located give the goal the optimum characteristics for the corresponding clinical applications.

The specific requirements of the borescope depend on whether it is used in water or air, the required image angle, and the critical distance from where the technician is to the part of the body where the inspection will take place.

As well as the required depth of field, if you want an image without distortions, among many other factors.

Cylindrical lenses and the investment system

The inversion system is a combination of cylindrical lenses, which are used to transmit images inside the endoscope.


The eye’s lens has the virtual enlargement of the image, also allowing the adjustment of the sharpness of the picture.

The high-resolution imager used in human medicine has an outer diameter of approximately 1.2 mm and has 50,000 individual fibers in order.

Each fiber’s diameters usually possess between 4 μm and 14 μm. The number of threads of the conductor varies between 3,000 and 50,000 depending on the field of application.

This driver executes the optical transport of the image of the objective to the eyepiece of the borescope. In this place, the idea is virtually enlarged by an ocular lens where the user can visualize it.

The borescope with a chip on the tip describes a relatively new technology in human medicine; it is integrated simply into a small camera’s end of the endoscope.

The image generated in the lens is transmitted directly to the video chip. This chip transforms the received optical information into electrical signals that are transferred to the controller located in the camera.

The technological revolution of the chip will achieve that these signals can have up to 2 megapixels.

Differences between rigid and flexible borescope

Rigid borescopes are ideal for applications where access is required only in a straight line up to the inspection objective, so they can not be bent unless designed in a personalized way.

  • In rigid boroscopes, image quality is better than in rigid fiber optic borescopes.
  • Rigid boroscopes are mainly used in applications with a straight corridor to the observation point. But flexible borescopes can access cavities that are around a curve.
  • Flexible boroscopes or fiberscopes are more expensive, are more fragile, and are more challenging to handle than rigid boroscopes.

Uses in medicine

The borescope or endoscope is a technical device whose use in the area of ​​medicine is to facilitate the differential diagnosis of pathologies.

The most significant advantage of using the endoscope lies in the facilities it offers to inspect organs and areas of the body, for which the classical radiological examination can not provide specific results.

Therefore, this instrument represents an essential tool for all diagnostics in modern medicine.

This device is used to inspect a cavity or a body organ, introducing it through a natural opening, such as the mouth, to perform a bronchoscopy or the rectum to perform a sigmoidoscopy.

The medical procedure where any borescope is used is called endoscopy.

In the current era, there is a wide variety of specific boroscopes to perform the various exploratory examinations that allow the development of excellent diagnoses due to the superb quality of the illumination and images.

It is used in the digestive tract, the trachea, esophagus, nasopharyngeal cavity, or any other organ challenging to access in the human body. It is indispensable for carrying out numerous explorations.

These explorations make it easier to know the patient’s diagnosis and identify his pathology.

In modern medicine, with the help of the borescope, high-resolution images of the place that has been examined are transmitted to a screen.

This visualization of the video sequences verifies any suspicion and provides findings to the doctor, which are extremely useful for recommending the most appropriate treatment according to the present pathology.

Unfortunately, these devices are costly for daily use nowadays, and not all medical specialists have them.

Endoscopy, in its beginnings, was only used in scans of the esophagus, stomach, and colon. It is currently employed in various organs to diagnose diseases in the ear, nose, throat, heart, urinary tract, joints, abdomen, and others.

Endoscopies have been classified into several categories, depending on the area of ​​the body where the investigation is performed.

The American Cancer Society classifies them into the following types:

  • Arthroscopy is used for the examination of joints. The borescope is inserted through a small incision near the joint to be examined.
  • Bronchoscopy is used to examine the lungs. The borescope is inserted through the nostrils or the mouth.
  • The colonoscopy is used for examination of the colon. The equipment is inserted through the rectum.
  • Cystoscopy is used to examine the bladder. The borescope is inserted through the urethra, the hole through which urine is excreted and leads to the bladder.
  • Enteroscopy is used for the examination of the small intestine. The borescope is inserted through the mouth or rectum.
  • Hysteroscopy is used to examine the inside of the uterus. The device is inserted through the patient’s vagina.
  • The laparoscopy allows exploring the abdominal or pelvic area. The borescope is inserted through a small incision in the abdomen’s skin near the extent that you want to examine during the endoscope.
  • Laryngoscopy is used to analyze your voice box or larynx. The endoscope is inserted through your mouth or nostril.
  • Mediastinoscopy examines the area between the lungs called the “mediastinum.” The endoscope is inserted through an incision over the sternum.
  • Upper gastrointestinal endoscopy examines the esophagus and the upper intestinal tract. The endoscope is inserted through your mouth.
  • Ureteroscopy is used to examine your ureter. The endoscope is inserted through your urethra.