https://www.sciencedaily.com/releases/2019/09/190920124654.htm

If these light structures are tightly focused by a lens, like a magnifying glass used as burning glass, highly intense three-dimensional light landscapes will be shaped, facilitating a significantly enhanced resolution in named applications. These kinds of light landscapes has paved the way to pioneering applications as Nobel prize awarded STED microscopy.

However, these nano-fields itself could not be measured yet, since components are formed by tight focusing which are invisible for typical measurement techniques. Up to now, this lack of appropriate metrological methods has impeded the breakthrough of nano-structured light landscapes as a tool for material machining, optical tweezers, or high-resolution imaging.