What is the difference between a rigid and flexible borescope?
A rigid borescope uses a series of individual lenses or a long gradient index relay lens to relay the image of the objective lens to an image plane where the eye lens can magnify it and present it to the eye for viewing. A flexible borescope uses a coherent fiber bundle with thousands of individual fibers to relay the image from the objective to the eyepiece. Due to the “pixelated” nature of the fiberscope image relay device, the image from a fiberscope is never as good as a similar diameter rigid borescope. There is also much less ability to focus a flexible borescope because the two end faces of the coherent fiber bundle are well defined planes. Pictures of both types of borescopes and comparison images from each can be viewed here.
