Conventional microscopes produce enlarged images of small structures or objects with the help of light. Nanoparticles, however, are so small that they hardly absorb or scatter light and, hence, remain invisible. Optical resonators increase the interaction between light and nanoparticles: They capture light in smallest space by reflecting it thousands of times between two mirrors. In case a nanoparticle is located in the captured light field, it interacts thousands of times with the light such that the change in light intensity can be measured. “The light field has various intensities at different points in space. This allows conclusions to be drawn with respect to the position of the nanoparticle in the three-dimensional space,” says Dr. Larissa Kohler from KIT’s Physikalisches Institut.
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Source: Phys.org