Laser-illuminated microscopy could see 10nm objects

It is claimed the advance represents a practical tool for biomedical and nanotechnology research.

‘Super-resolution optical microscopy has opened a new window into the nanoscopic world,’ said Ji-Xin Cheng, an associate professor of biomedical engineering and chemistry at Purdue University.

Conventional optical microscopes can resolve objects no smaller than about 300nm, a restriction known as the diffraction limit, which is defined as half the width of the wavelength of light being used to view the specimen.

However, researchers want to view molecules such as proteins and lipids, as well as synthetic nanostructures like nanotubes, which are a few nanometres in diameter.

Such a capability could bring advances in a diverse range of disciplines, from medicine to nanoelectronics, Cheng said.

‘The diffraction limit represents the fundamental limit of optical imaging resolution,’ Cheng said in a statement. ‘Stefan Hell at the Max Planck Institute and others have developed super-resolution imaging methods that require fluorescent labels.

‘Here, we demonstrate a new scheme for breaking the diffraction limit in optical imaging of non-fluorescent species. Because it is label-free, the signal is directly from the object so that we can learn more about the nanostructure.’