Seeing the invisible: light-based 3d imaging of opaque nanostructures
Nanostructures drive the world around us. Every modern electronic device contains integrated circuits and nano-electronics to provide its functionality. Advances in nanotechnology directly impact society by enabling smartphones, autonomous devices, the internet of things, data storage, and essentially all forms of advanced technology.  Fabricating such nanostructures crucially depends on having the tools to make them visible without destroying them. Modern nanodevices often have complex three-dimensional architectures with small features in all dimensions. While imaging methods that achieve nanometer-scale resolution exist, there are currently no compact tools that can look inside 3D nanostructures made out of metals and semiconductors without damaging their delicate internal structure.  I will address this challenge by developing compact tools to image 3D nanostructures in a non-invasive way. Even though most nanostructures are completely opaque to visible light, I will develop light-based methods, combined with computational imaging techniques developed in my previous ERC project, to look inside them with unprecedented resolution and contrast. Light-based imaging is unparalleled in speed and versatility, and allows contact-free detection. My proposal is to: 1) Use compact laser-produced soft-X-ray sources to image nanostructures with high 3D resolution and element-sensitive contrast; 2) Use laser-induced ultrasound pulses to image complex 3D nanostructures, even through strongly absorbing materials; 3) Employ computational imaging methods to reconstruct high-resolution 3D object images from the resulting complex diffraction signals. I will forge a coordinated research program to bring these concepts to reality.   This program provides exciting prospects for fundamental science and industrial metrology. I will go beyond the state-of-the-art in nano-imaging, to extend our vision into the complex interior of the smallest structures found in science and technology.