Industrial endoscopes or borescopes come in two distinct groups.
1. Rigid borescopes are stainless steel tubes with very precise lenses that are arranged to give good image quality at the eye piece. Rigid borescopes come in many diameters and in very many lengths. Some look straight ahead some look at 90', some have the ability to zoom in and out while others can swivel from almost straight to way past 90' but all are rigid in construction and have the traditional eye piece.
2. Flexible borescopes are as the name implies flexible. They will have the ability to articulate the viewing end in 2 or 4 directions. This enables the operator to drive the scope into complicated places. The viewing end of a flexible scope can have different viewing tips fitted, these will allow straight forward viewing or 90' viewing. The original flexible borescopes used to use fibre optics to transfer the light to the viewing end and then a different fibre optic bundle would take the image back to the eye piece. Fibre optic bundles used to look through are very costly to make as they have to be coherent which means the order of the individual optical lines has to finish in exactly the same order as it starts. The image is made up of several thousand dots, if these dots end up in a different place at the eye piece to where it started then the image would be mixed up and unviewable.
With the advances in technology in the field of digital cameras the flexible borescope evolved into the video borescope. It essentially looks similar to the flexible fibre scope. The difference is a camera is mounted in the viewing end and the signal is passed up the scope to the TV screen which has replaced the eye piece. The very latest video borescopes use LED lights in the viewing end which means the flexible section can be made much stronger as there is much less passing through it.
The quality and versatility of video scopes now is beyond belief. These kits can now record the images into video or pictures which can be transferred to computer and distributed easily.