Light passing through a thin glass fiber scatters into countless tiny speckles, like ripples on water from a thrown stone. Physicists call this graininess speckle noise. Because of it, images from an ultra-thin endoscope come out blurry, as if you're looking through fogged-up glass.
The researchers devised a program that removes this ripple. It breaks the image into parts, much like a chef separates bones from meat: some parts carry the large-scale details, others the fine noise. The program then stitches only the needed parts back together, yielding a clean picture. In experiments, an endoscope made of two fibers thinner than a human hair revealed fine lines on a paper target and discerned the structure of leaves.
This method allows us to peer into narrow passages where a regular camera can't fit — for example, inside blood vessels or into hard-to-reach cavities in machinery. Now, image quality no longer depends on the thickness of the probe.
Speckle noise isn't just a nuisance. From it, you can recover information about the surface, just as ripples on water tell you where a stone fell.
In science fiction, miniature probes with optical fibers explore patients' bodies in the film 'Fantastic Voyage'.