A longstanding rule of thumb with standard microscopes suggests that it is not possible to resolve things that are much smaller than the wavelength of light in one image. This limitation is typically attributed to the inability to capture evanescent waves with a standard imaging setup. The evanescent component of light emerging from an object of interest contains all of the ultra-high-resolution information that we’d love to see. However, it unfortunately decays within a very short propagation distance—typically much too short for a normal camera to pick up. Over the past several years, however, a number of new techniques are now challenging this assumed image resolution limit of the standard microscope. By placing a carefully designed sub-wavelength-sized element in very close proximity to an object, it is now possible to indirectly detect the shape of its evanescent field, which thus allows one to determine object features that are much smaller than the optical wavelength. In this work, Inampudi et al. consider a particular setup that should likely hold much promise for the future of these kinds of ultra-high-resolution imaging efforts. They present a reconfigurable grating-like structure that is made of multiple graphene strips, each of which can independently turn "on" and "off," so to speak, with an electronic signal. This reconfigurable grating eventually might allow the experimentalist to adaptively optimize how he can transfer the effects of the evanescent field to a normal camera, and thus might lead to a more efficient way to capture the super-sharp images of the future.
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