Speeded-Up Focus Control of Electrically Tunable Lens by Sparse Optimization

Electrically tunable lenses (ETL), also known as liquid lenses, can be focused at various distances by changing the electric signal applied on the lens. ETLs require no mechanical structures, and therefore, provide a more compact and inexpensive focus control than conventional computerized translation stages. They have been exploited in a wide range of imaging and display systems and enabled novel applications for the last several years. However, the optical fluid in the ETL is rippled after the actuation, which physically limits the response time and significantly hampers the applicability range. To alleviate this problem, we apply a sparse optimization framework that optimizes the temporal pattern of the electrical signal input to the ETL. In verification experiments, the proposed method accelerated the convergence of the focal length to the target patterns. In particular, it converged the optical power to the target at twice the speed of the simply determined input signal, and increased the quality of the captured image during multi-focal imaging

Reproducing reality with a high-dynamic-range multi-focal stereo display

With well-established methods for producing photo-realistic results, the next big challenge of graphics and display technologies is to achieve perceptual realism --- producing imagery indistinguishable from real-world 3D scenes. To deliver all necessary visual cues for perceptual realism, we built a High-Dynamic-Range Multi-Focal Stereo Display that achieves high resolution, accurate color, a wide dynamic range, and most depth cues, including binocular presentation and a range of focal depth. The display and associated imaging system have been designed to capture and reproduce a small near-eye three-dimensional object and to allow for a direct comparison between virtual and real scenes. To assess our reproduction of realism and demonstrate the capability of the display and imaging system, we conducted an experiment in which the participants were asked to discriminate between a virtual object and its physical counterpart. Our results indicate that the participants can only detect the discrepancy with a probability of 0.44. With such a level of perceptual realism, our display apparatus can facilitate a range of visual experiments that require the highest fidelity of reproduction while allowing for the full control of the displayed stimuli.</jats:p

Promocijas darbs

Elektroniskā versija nesatur pielikumusŠajā darbā ir izklāstīti šķidro kristālu difuzoru projektēšanas un optimizācijas laikā iegūtie rezultāti, to ražošanas tehnoloģija un pielietojums uz galvas nēsājamos paplašinātās realitātes displejos. Šķidro kristālu difuzori tiek pielietoti liela izmēra displejiem, taču to pielietojums tuvu lietotāja acīm izvirza jaunas prasības attiecībā uz ļoti maziem izmēriem un augstu kontrastu, kā arī caurspīdīgumu. Piemērotas modelēšanas izmantošana šķidro kristālu sastāva projektēšanai un zināmo materiālu izmantošanas un tehnoloģijas optimizēšanai ļauj izpildīt augstāk minētās prasības ar samazinātu eksperimentālā darba apjomu. Gadījumos, kad tradicionālos displeju materiālus nevarēja izmantot, tika izstrādāti citi materiāli, proti, silīcija oksinitrīda plānās kārtiņas ar maināmu laušanas koeficientu.This thesis presents the results obtained during design and optimization of liquid crystal diffusers, their production technology and application in augmented reality head mounted displays. Liquid crystal diffusers have been proven for large form factor displays but their application for near eye distances provide new requirements in terms of very small dimensions, and high contrast and transparency. Using appropriate physical modelling to designing liquid crystal composition and for optimizing employment and technology of known materials, allows to fulfil above mentioned requirements with reduced volume of experimental work. In cases when traditional display technology materials could not be applied, other materials were developed, namely silicon oxy nitride thin films with variable index of refraction