Two-dimensional point spread matrix of layered metal–dielectric imaging elements
Spotlight summary: Linear shift-invariant (LSI) models are an indispensable tool in the design of imaging systems. Microscopy in particular makes extensive use of LSI models, with physical design considerations often described and evaluated by the effect produced on the system point-spread function (PSF) and/or the transfer function. The simplicity and clarity of LSI analysis is in sharp contrast to the controversy and debate that surrounded superlenses ten short years ago. It is therefore interesting to note the evolution of the field to a point where superlenses are described in the immanently practical framework of LSI systems, as done by the authors of this manuscript.
Koty?ski and coauthors characterize planar multilayers as LSI imaging systems and calculate the corresponding PSFs and transfer functions. They use a clear and tractable analysis to isolate several of the most interesting features of planar superlenses, for example: the significant differences between the transverse-electric and transverse-magnetic polarization responses due to surface plasmon resonance; the potential for the transfer of evanescent waves, giving rise to superresolution; and the strong coupling that can exist between polarization states. Similar to more traditional applications, the plotting of transfer functions and PSFs gives significant insight into the imaging properties of the planar superlens. As the authors show by example, the insight provided can be leveraged to modify the system to tailor the optical response. In the given example a diffractive nanostructure is designed, analyzed, and discussed. It should be noted however, that the addition of transverse structure (such as this nanostructure) does invalidate the shift-invariant nature of image formation by the multilayer.
Technical Division: Light–Matter Interactions
ToC Category: Materials
|OCIS Codes:||(050.0050) Diffraction and gratings : Diffraction and gratings|
|(100.6640) Image processing : Superresolution|
|(110.0110) Imaging systems : Imaging systems|
|(260.0260) Physical optics : Physical optics|
|(160.4236) Materials : Nanomaterials|
|(310.6628) Thin films : Subwavelength structures, nanostructures|
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