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New Optical Method for Producing Hhigh-res, 3-D Images of Nanoscale Objects

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Stanford engineering graduate student Ashwin Atre uses an electron microscope to investigate the optical properties of nanoscale materials in three dimensions. (Linda A. Cicero / Stanford News Service)

To design the next generation of optical devices, ranging from efficient solar panels to LEDs to optical transistors, engineers will need a 3-dimensional image depicting how light interacts with these objects on the nanoscale. Unfortunately, the physics of light has thrown up a roadblock in traditional imaging techniques: the smaller the object, the lower the image's resolution in 3-D. Now, engineers at Stanford and the FOM Institute AMOLF, a research laboratory in the Netherlands, have developed a technique that makes it possible to visualize the optical properties of objects that are several thousandths the size of a grain of sand, in 3-D and with nanometer-scale resolution. The technique involves a unique combination of two technologies, cathodoluminescence and tomography, enabling the generation of 3-D maps of the optical landscape of objects, said study lead author Ashwin Atre, a graduate student in the lab group of Jennifer Dionne, an assistant professor of materials science and engineering.

For decades, techniques to image light-matter interactions with sub-diffraction-limited resolution have been limited to 2D. The technique can be used to probe many systems in which light is emitted upon electron excitation. "It has applications for testing various types of engineered and natural materials," Atre said. "For instance, it could be used in manufacturing LEDs to optimize the way light is emitted, or in solar panels to improve the absorption of light by the active materials." The technique could even be modified for imaging biological systems without the need for fluorescent labels.