Synopsis: Better than Diffraction

A new microscopy method allows the imaging of nanostructures that are smaller than one eighth of the wavelength of the light used to illuminate them.
Synopsis figure
Courtesy Tung-Yu Su/National Taiwan University

Optical microscopes are widely used in all areas of science to image small objects. However, because of their design and the limits of diffraction, the smallest features that conventional microscopes can image are about half the wavelength of the light they use. Writing in Physical Review Letters, Shi-Wei Chu, at the National Taiwan University, and colleagues report a new technique that overcomes this resolution limit and can image nanostructures 70 nanometers in size—less than one eighth of the wavelength of the visible light used in their setup.

The group fitted a standard optical microscope with a laser and used it to image a sample containing gold nanoparticles. The laser wavelength was chosen so that it was resonant with the sharp plasmonic resonance exhibited by the particles. As a consequence, the laser light experienced particularly strong scattering. By adjusting the intensity of the laser, the researchers were able to reach, for the first time, a regime in which the light scattered from an isolated particle was saturated. With proper image processing techniques, such saturation behavior could be exploited to deliver sharper images of the plasmonic nanostructures.

While this method only works for gold nanoparticles, the particles can be selectively embedded into other materials, allowing them to be imaged. Although other recently demonstrated techniques, mostly based on fluorescence microscopy, allow comparable or even better resolution, this gold-nanoparticle method has an important advantage: samples can be imaged repeatedly without damage and with no loss in scattering intensity that, in fluorescence-based schemes, inevitably occur because of the bleaching of the fluorescing molecules. – Katherine Wright


Announcements

More Announcements »

Subject Areas

OpticsNanophysics

Previous Synopsis

Atomic and Molecular Physics

Fermi Gas Goes into Deep Degeneracy

Read More »

Next Synopsis

Related Articles

Synopsis: Starting Fluid for Laser Fusion
Energy Research

Synopsis: Starting Fluid for Laser Fusion

A laser-based fusion experiment demonstrates that liquid fuel capsules could rectify problems encountered with ice-based fuel capsules. Read More »

Synopsis: Graphene’s Elegant Optics Explained
Graphene

Synopsis: Graphene’s Elegant Optics Explained

Theoretical calculations anchor graphene’s simple optical absorption in its two-dimensional structure instead of its cone-shaped energy bands. Read More »

Synopsis: Sharper Vision for Infrared Telescopes
Optics

Synopsis: Sharper Vision for Infrared Telescopes

Converting infrared light to visible light might boost the sensitivity of infrared telescope arrays. Read More »

More Articles