A new, air-filled optical fiber bundle could dramatically improve medical endoscopes. This technology could also help create endoscopes that produce images using infrared wavelengths. If so, this breakthrough would allow diagnostic procedures that aren’t currently possible.
In the Optical Society (OSA) journal Optics Letters, University of Bath (U.K.) researchers showed that these new fiber optic bundles (called air-clad imaging fibers) deliver resolution equal to the best commercial imaging fibers. And the bundles do this at twice the wavelength range of these fibers. Because of this, these air-clad imaging fibers could help create new, smaller endoscopes with even better resolutions.
HOW ENDOSCOPES WORK
Used in minor surgery and imaging, endoscopes use bundles of optical fibers to obtain images from inside the body. Light that falls on one end of the fiber bundle travels through each fiber to the far end. This process sends a picture as thousands of spots, much like pixels in a digital picture.
TESTING THE BUNDLES
Instead of using cores and claddings of two types of glass, the new bundles use an array of glass cores covered by hollow glass capillaries filled with air. These air-filled capillaries act as the fiber cladding.
To test the imaging fibers, the research team created an air-clad fiber bundle. This bundle matched the resolution of a leading commercial fiber (with the same spacing between cores). The team then stacked multiple, smaller honeycomb structures to place more than 11,000 cores into the fiber.
The researchers used the air-clad fiber bundle and the commercial fiber to image a standard test target image. And the result? The air-clad fiber performed well beyond the wavelength range that a visible camera could detect. And when the researchers switched to an infrared camera, the fiber created a clear image at twice the wavelength that the commercial fiber reached.
REAL-WORLD USE OF FIBER BUNDLES
Along with medical diagnosis and care, the new optical fiber bundles could be used for industrial applications. These uses include monitoring the contents of hazardous machines and viewing the inside of oil and mineral drills. These types of fibers are becoming more and more popular for a variety of purposes.
OFS Laboratories, one of the world’s leading optical fiber research labs, and the research arm of OFS, has performed major work in this area. The development of Microstructure Optical Fibers (MOFs) is one result of this work. The MOFs created by OFS Labs are a new class of optical fibers that are substantially different from conventional optical fibers.
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