If you are planning to purchase a borescope, then it is extremely important to consider the specifications of a borescope along with its price.
1. Rigidity and flexibility
2. Size and length
3. Angle of View (AOV) and Field of View (FOV)
4. Magnification and Illumination
Rigidity and Flexibility of a Borescope
Basically, there are two types of borescopes. A borescope is either rigid or flexible. A rigid borescope usually gives high quality images. Such borescopes are found as less expensive, however, if there are spaces, this type of borescope would not be able to penetrate.
A rigid borescope consists of a single hollow tube along with an eyepiece, lenses and a bulb or any other form of light.
The lenses that are commonly used for these borescopes are achromats, Harold Hopkins or GRIN lenses.
Although rigid borescopes are less expensive than flexible borescopes, their movement is limited. Users can examine objects only up to a certain level due to lack of free mobility.
In such cases, a fiberscope that is flexible is usually preferred. These borescopes can bend into a total of four different directions for giving crisp imaging of pictures.
Size and Length of Borescopes
Ideally, you need to select a borescope that can give better visibility when it is bent. For holes of various sizes and dimensions, the best choice is to go for borescopes of equal sizes or length.
Angle of View (AOV) and Field of View (FOV) of a Borescope
When you take the longitudinal axis of the middle part of a rigid and the top most part of flexible borescope, the AOV from the center will be the FOV.
Based on the type and location of your object to be examined, you can opt for borescopes with different angles.
A mirror tube with AOV of 90• can be used if the subject is positioned at 0• angle. If you want to check a subject positioned at an angle that is challenging to reach, such as any part of a motor or engine, you can use a borescope having an AOV of 120• that can help you look backwards easily.
Regarding the FOV of a borescope, it can be of either narrow, medium or wide ranged. On an average, the FOV of a borescope is exactly 37•. If the FOV increases and is wider in range than this, the lesser its magnification will be.
And the narrower the FOV, the greater will be the magnification. In order to view the entire frame at once, you can set your borescope at a 90• angle. However, you also have the option of a 30• telephoto to get closer for a clearer view of the subject.
Magnification of Borescopes
Both microscopes and loupes usually have a very restricted DOP (depth of field). They can only focus images at certain distances and therefore, their magnification is also very limited.
A borescope, on the other hand, has an extensive DOF (depth of field). Therefore, borescopes are easier to use as users do not have to refocus them from time to time.
The closer you place a subject to your borescope's lens, the more crisp and vivid will the magnification be. In order to calculate the magnification, you need to figure out the distance of your object from the borescope's lens. Whether you are using a rigid borescope or a flexible one, you need to follow the same method for both types of borescopes.
Illumination of Borescopes
In order to look inside the dark cavities of an object, there has to be some source of light to clearly examine the object.
Earlier, hot lamps were used to examine dark areas of an object. However, today there are many cheaper borescopes that use the same lamps for illumination that can be quite dangerous if not used correctly. Using such bulbs may lead to heating and unwanted contamination.
Nevertheless, today, there are many high-quality borescopes available in the market which use fiber optic for illumination.
In these types of borescopes, the high-quality glass fibers provide illumination. Such borescopes are safer and more convenient to use than those that provide illumination through hot bulbs.
To Sum Up
All in all, in order to purchase a borescope of good quality, it is important to consider its FOV and AOV first. Moreover, the magnification and rigidity or flexibility should also be checked while making this investment.