Superoscillation takes nanoscale measurements with light

According to Nanyang Technological University (NTU Singapore), devices that use light to see objects, such as microscopes, have a fundamental limitation based on the laws of physics, which is their resolving power.

The smallest distance that optical devices can reliably image is equal to half the wavelength of the light used, or the “diffraction limit”. The diffraction limit is above 400nm, about half the wavelength of near infrared light and 250 times smaller than the width of a human hair.

Scientists are interested in observing objects like viruses and nanoparticles that range in size from 10 to 100nm, so an optical resolution of 400nm is insufficient. Currently, nanometre-scale measurements are made using indirect or non-optical methods, such as scanning electron microscopy, which are not always feasible, can be time-consuming and require costly equipment to operate.

However, an advance described in Science by Prof Nikolay Zheludev and Dr Guanghui Yuan at NTU’s School of Physical & Mathematical Sciences describes a new optical method that can measure displacements of a nanometre using near infrared light.