Because nanoscale objects are so incredibly small, they don't reflect enough light for even the best microscopes to discern details such as their color. A new lighting system, however, addresses that problem by acting as a tiny spotlight.
Developed by scientists at the University of California - Riverside, the "magic wand"-like setup takes the light from a tungsten lamp and focuses it into the 5-nanometer-wide tip of a silver nanowire. A conical beam of light is then emitted from that tip, much like a tiny version of the beam produced by a flashlight.
Located directly beneath the silver nanowire is the object to be imaged, lying on a clear glass platform. The intense light beam passes through that object, through the platform and down onto a spectrometer, where it forms a ring-shaped pattern.
By analyzing that pattern, it's possible to ascertain the manner in which the object absorbed and scattered the light. Utilizing that information, it's in turn possible to determine and reproduce the color and surface details of the object.
In a test of the technology, the team used it to obtain what are claimed to be the first-ever true color photos of carbon nanotubes.
"The atomically smooth sharp-tip silver nanowire and its nearly scatterless optical coupling and focusing is critical for the imaging," says Assoc. Prof. Ruoxue Yan, who is leading the study along with Assoc. Prof. Ming Liu. "Otherwise there would be intense stray light in the background that ruins the whole effort."
It is hoped that once developed further, the technology could have applications in tasks such as the production of semiconductor materials, nanoelectronics and quantum optical devices.
A paper on the research was recently published in the journal Nature Communications.
