Ultra-high precision lithography, microscopy, and imaging
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abstract
The resolution limit of a traditional optical imaging system is about half wavelength of the illuminating light as discovered by Abbe over a century ago. This Abbeâ s diffraction limit has become a critical bottleneck for modern super-resolution optical microscope and optical lithography. The objective of this project is to explore and advance novel techniques for super-resolution optical imaging and optical lithography. Such super-resolution techniques can have important applications in both fundamental physics and applied sciences. For optical lithography, several promising schemes were proposed to overcome the diffraction limit. Those include mechanisms based on doppleron, quantum dark state, coherent Rabi oscillations and magnetic resonance lithography. The study in this direction has significantly moved toward a practical application, e.g., in methods using coherent Rabi oscillations and magnetic resonance, the requirements of quantum entanglement and multi-photon absorber are successfully eliminated. Furthermore, these schemes can in principle generate arbitrary one and two dimensional patterns which is an important requirement for practical applications. However, there are still several problems to address for practical applications. In this proposal, the major objective will be to study the issues relating to a final realization of a practical sub-wavelength optical lithography scheme. For optical imaging, several schemes were proposed to overcome the diffraction limit. It is shown that the separation between two atoms can be determined from the resonance fluorescence spectrum and the resolution can be improved up to λ/500. This scheme is extended to arbitrary atoms in one and two dimensional spaces and the positions of the atoms even if the presence of the dipole-dipole interactions can be extracted. The method using resonance fluorescence may thus become a useful optical microscopy with super-resolution. Recently, a new scheme was proposed for super-resolution microscopy where the graphene surface plasmon is used as an illumination light source in a structured illumination microscopy (SIM). Since the graphene surface plasmon has a much larger wavenumber than the excitation wavelength, the resolution of linear SIM can be extended far beyond the diffraction limit. These methods are essentially far-field microcopies and they do not require point-by-point scanning which can be faster. This project will carry out studies to design a viable system to improve these schemes until the realization of a practical super-resolution microscopy. A major thrust will be on designing the scheme that is not only far-field but is able to do microscopy without point-by-point scanning. In addition, the proposed method would lead to the field of view to be macroscopic and the light source to be sufficiently low to avoid sample damaging. Such kind of super-resolution optical microscope should have a high impact in nanotechnology and biomedical imaging.
