Authors:

Ian Holda

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About Paper:

Conventional far-field imaging techniques have a maximum achievable resolution of approximately half a wavelength, and many applications, such as nanotechnology and biological imaging, would benefit from higher resolution. Here we describe two experiments which relate to new paradigms for sensing and imaging beyond the diffraction limit, based on the concepts of relative motion in structured illumination and correlations between photon counting detectors. The first experiment involves translating nanostructured membranes through a standing wave field in an interferometer and using intensity measurements at one of the interferometer arms to extract the physical parameters of the membrane. A mathematical model based on plane wave decomposition was developed to assist experiment design and facilitate inversion for membrane parameters. The approach used in this experiment will provide the capability to characterize multilayered dielectric structures with far- subwavelength resolution, significantly improving on what is possible with conventional methods such as ellipsometry. The second experiment involves measuring Hanbury Brown and Twiss (HBT) correlations through a heavily scattering medium. After transmission through the medium, scattered light falls upon two detectors. One detector is stationary and the other moved in set increments. Coincidences between arriving photons are measured to build up correlations over detector position, which are related to the properties of the light before it entered the medium. This experiment will improve understanding of how heavy optical scattering affects HBT correlations, potentially enabling a new paradigm for super resolution sensing.

Source:

Purdue University / 2023

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Co-authors:

Ian Holda