When attempting to view inside a cavity with a borescope, (whether that cavity is inside a wall, a machine, or human), in most cases it’s going to be pretty dark. That’s where illumination systems come into play. Illumination systems can be incorporated into a borescope or endoscope, or constructed as a separate, standalone entity.
While the illumination fibers can be arranged in a variety of configurations, when incorporated in a flexible scope, the most common geometric pattern is an annular ring surrounding the imaging fiber and lenses. This will provide the most evenly lit field of view. Obviously, the more illumination fibers that can be stuffed into the scope’s maximum diameter, the more light there will be for viewing.
A light/illumination sheath is a separate device that encloses the illumination fibers, and mounts/slides over the borescope or endoscope. This set up allows for use of the scope with or without illumination, depending on the lighting situation.
A light cable is a flexible cable that transmits light from a light source to a scope. Some cables incorporate fibers as the transmission medium, others use clear liquids. Light sources can be bench top systems powered by AC outlets; others are hand held LED units powered by rechargeable batteries.
Light guides (or pipes) are usually rigid devices that bring light from one location to another, where the geometric relationship between the two locations remains the same all the time. These units are usually made up of many illumination fibers fused, or potted together, and bent into a specific shape.
The illumination fibers used to manufacture these devices are provided in two different materials: plastic or glass. Plastic fibers are less costly, but have a lower light transmission rating. Glass fibers are usually more costly, but provide a much better light throughput. In addition, plastic fibers have an Numerical Aperture (NA) of .5 while the borosilicate glass fibers can range from NA .4 to NA .86. That allows the light to spread out and illuminate the target area the fiberscope or borescope needs to see.
Coming up in our blog, we will have an entry were we discuss the different sterilization methods available for medical devices. In another entry, we will present our newly launched custom inventory control system.