Interscale mixing microscopy: far-field imaging beyond the diffraction limit

Optical microscopy is widely used to analyze the properties of materials and structures, to identify and classify these structures, and to understand and control their responses to external stimuli. The extent of available applications is determined largely by the resolution offered by a particular microscopy technique. Here we present an analytic description and an experimental realization of interscale mixing microscopy, a diffraction-based imaging technique that is capable of detecting and characterizing wavelength/10 objects in far-field measurements with both coherent and incoherent broadband light. This technique is aimed at analyzing subwavelength objects based on far-field measurements of the interference created by the objects and a finite diffraction grating. A single measurement, analyzing the multiple diffraction orders, is often sufficient to determine the parameters of the object. The presented formalism opens opportunities for spectroscopy of nanoscale objects in the far field.