Rethinking Near-to-Eye Displays and Holographic Fiber Endoscopy through Wavelength Multiplexing

Abstract

In recent years, advancements in display and imaging technologies have enabled remarkable applications such as Augmented Reality (AR) displays, which overlay virtual content onto the physical environment, and fiber endoscopes, which assist in delicate surgical procedures. Although continuous improvements in hardware and engineering have significantly enhanced these systems, their ultimate performance remains fundamentally constrained by physical and information-theoretical limits. For waveguide-combiner-based AR glasses, the primary physical limitation is the field of view, which is restricted by total internal reflection (TIR)—a phenomenon inherently linked to the material properties of the waveguide. In the case of fiber endoscopes, performance degradation arises from phase distortions induced by light scattering within tissue and by mechanical bending of the fiber, which can lead to image deterioration or even complete signal loss. Importantly, these fundamental constraints often manifest as uncertainty products, implying that specific system parameters can be optimized by relaxing others that are less critical. Furthermore, by incorporating additional information through complementary modalities, it becomes possible to overcome previously established performance limits. This dissertation investigates how wavelength multiplexing can be exploited to enhance the performance of AR displays and fiber endoscopes beyond their conventional boundaries. Specifically, this thesis demonstrate how Volume Holographic Gratings (VHGs) can be utilized to expand the field of view of AR devices beyond the classical TIR limit. In addition, it shows that Synthetic Wavelength Holography (SWH) can effectively mitigate the detrimental effects of phase perturbations in fiber endoscopes caused by fiber bending and strong tissue scattering between the fiber tip and the sample which limited information that can be obtained by the system.