Deeply sub-wavelength non-contact optical metrology of sub-wavelength objects

Microscopes and various forms of interferometers have been used for decades in optical metrology objects that are typically larger than the wavelength light ?. Metrology sub-wavelength objects, however, was deemed impossible due to diffraction limit. We report measurement physical size with deeply accuracy by analyzing pattern coherent scattered deep learning enabled analysis. With a 633 nm laser, we show width slits an opaque screen can be measured ? ?/130 single-shot or ?/260 (i.e., 2.4 nm) when combining measurements patterns at different distances from object, thus challenging scanning electron microscopy ion beam lithography. In numerical experiments, technique could reach beyond ?/1000. It is suitable high-rate non-contact nanometric sizes randomly positioned smart manufacturing applications integrated processing tools.