New optical technique paves the way for "hair-thin" endoscopes
Medical endoscopes may look small, but their tips are actually several millimeters wide, making them too big to image living cells within the body. A new system, however, allows users to view images through a single ultra-thin strand of optical fiber.
Just one tenth the width of a standard endoscopic optical cable, individual strands of optical fiber can much more easily be inserted into the body via a needle, then used to view living cells. Unfortunately, though, it's very challenging to obtain useable images directly through such strands, as they scramble the light that passes through them.
One solution to this problem involves figuring out the manner in which an individual strand scrambles light, then using that knowledge as a key to"decode" its garbled light patterns into understandable images. As the strand bends and twists, though, that key changes, and has to be recalculated all over again.
Led by Dr. David Phillips, scientists from the University of Exeter and elsewhere have developed a way around that limitation.
The process is inspired by an astronomical technique, in which optical distortions caused by atmospheric turbulence are compensated for by paying attention to a reference "guide star." Because the astronomers already know what that star is supposed to look like, they can correct the distorted images simply by adjusting them to make the star appear "right" again.
In the case of an optical fiber strand endoscope, a small brightly fluorescing particle on the end of the strand serves the same purpose as a guide star. Since the proper appearance of that particle is already known, it's easy to automatically compensate for changes in the scrambled-light key that occur as the strand twists and bends.
As a result, it's possible to continuously obtain clear images of tiny targets via that strand.
"We hope that our work brings the visualization of sub-cellular processes deep inside the body a step closer to reality – and helps to translate this technology from the lab to the clinic," says Philips.
A paper on the research, which also involved scientists from Boston University and Germany's Liebniz Institute of Photonic Technologies, was recently published in the journal Nature Communications.
Source: University of Exeter