Lensless light could enable detailed human body imaging

Very high resolution images in the human body are a step closer to being realised, after breakthrough research by scientists at the University of Twente.

An advanced wavefront shaping method was combined with unique optical fibres from the Max Plank Institute for the Science of Light, enabling lensless focusing of light at high resolutions not previously achieved.

Optical imaging using ultrathin fibres is useful as it enables doctors to observe the human body from within using endoscopes. However the resolution of current endoscopes is at best, 1µm, and does not allow certain biological features to be observed.

Fibre endoscopes suffer from images being scrambled as they travel — a problem photonic crystal fibres solve.

The photonic crystal fibres are built from a single material – unlike conventional fibres which are made of outer cladding and an inner core. The structure of conventional fibres allows for light transmission through total internal reflection. However for photonic crystal fibres, light guiding is achieved with the use of deliberate air-filled holes in the cladding. Using this method, the researchers were able to focus a laser beam through the fibre down to 0.53µm using visible red light.

Building on previous work carried out at the University of Twente on complex wavefront shaping, the team focused images that would otherwise be scrambled by light bouncing off the – sometimes irregular – wall of the fibre. This is managed by pre-shaping the light into the form needed to make a sharp image before the light enters it.

Using complex wavefront shaping in conjunction with a photonic fibre allowed for high resolution endoscopic imaging using fibres so thin they could enter blood vessels slightly thicker than a human hair.

The research was published in Optics Letter 41.