Date of Award
Doctor of Philosophy (PhD)
Modern optical imaging systems make extensive use of computational power for analog pre-processing, analog to digital conversion and digital post-processing. The joint design of these elements can be used to optimize the information throughput of optical imaging systems. This paradigm, termed computational optical imaging, aims at optimizing the output of optical systems in the form of imaging metrics, multidimensional imaging, feature detection, compressive sensing, etc. However, most optical imaging systems rely on the scalar wave theory of light to analyze these modern systems. Light, being an electromagnetic wave is vectorial in nature leading to significant errors in the scalar model when the propagation medium is anisotropic, inhomogeneous or non-linear. Electromagnetic optics, on the other hand, is an all-encompassing theory of light in the classical limit that takes into account the coupled nature of electric and magnetic fields.
In this respect, the effects of anisotropic emission from a fixed dipole emitter on high numerical aperture super-resolution microscopy are investigated. Wide field microscope configurations that allow simultaneous acquisition and measurement of the 3D position and orientation parameters of multiple fixed dipole emitters are proposed. The performance limits of these systems for the 5D imaging of fixed dipole emitters are quantified through comparison of the Cramer-Rao lower bounds in a photon limited environment. Further, experimental validation is provided for simultaneously estimating the 5D dipole parameters using the double-helix phase mask. Binary multi-level fabrication of efficient phase modulation elements to engineer the Green's tensor response of the system to a dipole input is demonstrated.
High numerical aperture objectives give rise to steep incident angles on lens surfaces, leading to resolution losses in imaging systems due to aberrations caused by the incorrect assumption of linearity between the incident and refracted angles at material interfaces. A new paradigm, termed infinitely refraction-linear artificial material (IRAM), is proposed to tackle this problem. IRAM maintain the linear relationship between incident and refracted angles beyond the paraxial limit. The inherent anisotropic material parameter requirements for IRAM are summarized. The performance of IRAM lenses is compared to that of conventional isotropic lenses by simulating the diffraction limited spot size of these lenses in Zemax. It is shown that with proper design IRAMs have the potential to improve the resolution of optical imaging systems. Further, another class of artificial metamaterials that use magnetic resonance to realize exotic optical properties is discussed as candidates for super-resolution using the super-lensing effect.
Agrawal, Anurag Satish, "Computational Imaging using Electromagnetic Optics" (2014). Electrical Engineering Graduate Theses & Dissertations. 8.