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Scientists at Nanyang Technological University, Singapore (NTU Singapore) have developed a new way to measure distances at the nanoscale—one nanometer being one billionth of a meter—using light.

Devices that use 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 can reliably image is equal to half the wavelength of the light used, known as the "diffraction limit."

The diffraction limit is therefore above 400 nanometers, about half the wavelength of near infrared light. This is some 250 times smaller than the width of a human hair (100 microns).

But since scientists are interested in observing extremely small objects like viruses and nanoparticles that range in size from 10 to 100 nanometers, an of 400 nanometers is insufficient.

Currently, nanometer-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, a discovery published in the journal Science by Professor 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 nanometer—the smallest distance ever directly measured, using near infrared light.

To read more, click here.
Category: Science