An autostereoscopic device for mobile applications based on a liquid crystal microlens array and an OLED display

In recent years, many experimental and theoretical research groups worldwide have actively worked on demonstrating the use of liquid crystals (LCs) as adaptive lenses for image generation, waveform shaping, and non-mechanical focusing applications. In particular, important achievements have concerned the development of alternative solutions for 3D vision. This work focuses on the design and evaluation of the electro-optic response of a LC-based 2D/3D autostereoscopic display prototype. A strategy for achieving 2D/3D vision has been implemented with a cylindrical LC lens array placed in front of a display; this array acts as a lenticular sheet with a tunable focal length by electrically controlling the birefringence. The performance of the 2D/3D device was evaluated in terms of the angular luminance, image deflection, crosstalk, and 3D contrast within a simulated environment. These measurements were performed with characterization equipment for autostereoscopic 3D displays (angular resolution of 0.03 )

Subjective evaluation of an active crosstalk reduction system for mobile autostereoscopic displays

The Quality of Experience (QoE) provided by autostereoscopic 3D displays strongly depends on the user position. For an optimal image quality, the observer should be located at one of the relevant positions, called sweet spots, where artifacts reducing the QoE, such as crosstalk, are minimum. In this paper, we propose and evaluate a complete active crosstalk reduction system running on an HTC EVO 3D smartphone. To determine the crosstalk level at each position, a full display characterization was performed. Based on the user position and crosstalk profile, the system first helps the user to find the sweet spot using visual feedback. If the user moves away from the sweet spot, then the active crosstalk compensation is performed and reverse stereo phenomenon is corrected. The user preference between standard 2D and 3D modes, and the proposed system was evaluated through a subjective quality assessment. Results show that in terms of depth perception, the proposed system clearly outperforms the 3D and 2D modes. In terms of image quality, 2D mode was found to be best, but the proposed system outperforms 3D mode

A Review and Selective Analysis of 3D Display Technologies for Anatomical Education

The study of anatomy is complex and difficult for students in both graduate and undergraduate education. Researchers have attempted to improve anatomical education with the inclusion of three-dimensional visualization, with the prevailing finding that 3D is beneficial to students. However, there is limited research on the relative efficacy of different 3D modalities, including monoscopic, stereoscopic, and autostereoscopic displays. This study analyzes educational performance, confidence, cognitive load, visual-spatial ability, and technology acceptance in participants using autostereoscopic 3D visualization (holograms), monoscopic 3D visualization (3DPDFs), and a control visualization (2D printed images). Participants were randomized into three treatment groups: holograms (n=60), 3DPDFs (n=60), and printed images (n=59). Participants completed a pre-test followed by a self-study period using the treatment visualization. Immediately following the study period, participants completed the NASA TLX cognitive load instrument, a technology acceptance instrument, visual-spatial ability instruments, a confidence instrument, and a post-test. Post-test results showed the hologram treatment group (Mdn=80.0) performed significantly better than both 3DPDF (Mdn=66.7, p=.008) and printed images (Mdn=66.7, p=.007). Participants in the hologram and 3DPDF treatment groups reported lower cognitive load compared to the printed image treatment (p \u3c .01). Participants also responded more positively towards the holograms than printed images (p \u3c .001). Overall, the holograms demonstrated significant learning improvement over printed images and monoscopic 3DPDF models. This finding suggests additional depth cues from holographic visualization, notably head-motion parallax and stereopsis, provide substantial benefit towards understanding spatial anatomy. The reduction in cognitive load suggests monoscopic and autostereoscopic 3D may utilize the visual system more efficiently than printed images, thereby reducing mental effort during the learning process. Finally, participants reported positive perceptions of holograms suggesting implementation of holographic displays would be met with enthusiasm from student populations. These findings highlight the need for additional studies regarding the effect of novel 3D technologies on learning performance

Augmented Reality for Restoration/Reconstruction of Artefacts with Artistic or Historical Value

The artistic or historical value of a structure, such as a monument, a mosaic, a painting or, generally speaking, an artefact, arises from the novelty and the development it represents in a certain field and in a certain time of the human activity. The more faithfully the structure preserves its original status, the greater its artistic and historical value is. For this reason it is fundamental to preserve its original condition, maintaining it as genuine as possible over the time. Nevertheless the preservation of a structure cannot be always possible (for traumatic events as wars can occur), or has not always been realized, simply for negligence, incompetence, or even guilty unwillingness. So, unfortunately, nowadays the status of a not irrelevant number of such structures can range from bad to even catastrophic. In such a frame the current technology furnishes a fundamental help for reconstruction/restoration purposes, so to bring back a structure to its original historical value and condition. Among the modern facilities, new possibilities arise from the Augmented Reality (AR) tools, which combine the virtual reality (VR) settings with real physical materials and instruments. The idea is to realize a virtual reconstruction/restoration before materially acting on the structure itself. In this way main advantages are obtained among which: the manpower and machine power are utilized only in the last phase of the reconstruction; potential damages/abrasions of some parts of the structure are avoided during the cataloguing phase; it is possible to precisely define the forms and dimensions of the eventually missing pieces, etc. Actually the virtual reconstruction/restoration can be even improved taking advantages of the AR, which furnish lots of added informative parameters, which can be even fundamental under specific circumstances. So we want here detail the AR application to restore and reconstruct the structures with artistic and/or historical valu

Roadmap on 3D integral imaging: Sensing, processing, and display

This Roadmap article on three-dimensional integral imaging provides an overview of some of the research activities in the field of integral imaging. The article discusses various aspects of the field including sensing of 3D scenes, processing of captured information, and 3D display and visualization of information. The paper consists of a series of 15 sections from the experts presenting various aspects of the field on sensing, processing, displays, augmented reality, microscopy, object recognition, and other applications. Each section represents the vision of its author to describe the progress, potential, vision, and challenging issues in this field

Adaptive micro-optical phase modulators based on liquid crystal technology

Mención Internacional en el título de doctorThis thesis began with the project “Advanced Devices of Liquid Crystal and Electroluminescent Organic Diodes. Hybrid Applications for 3D Vision” funded by the Spanish government. The goal of this project was the development of optical devices to achieve 3D vision in portable devices without glasses or external elements. In order to achieve the goals of this project, solutions based on liquid crystal are considered. Specifically, adaptive micro-optical phase modulators based on liquid crystal technology are researched in depth. The gradient of the refractive index varies spatially the phase delay experienced by an impinging wavefront of a light beam. By using this effect, any refractive optical element may be reproduced with the proper voltage gradient applied to the sample. This is the main operating principle of the micro-optical phase modulators proposed in this thesis. As original contribution of this thesis, a novel algorithm to solve the position of a nematic liquid crystal molecular director is proposed. Once the liquid crystal is completely characterized, the developing of a specific model to know the electro-optic response of the micro-optical phase modulators is also relevant. Another original contribution is a novel equivalent electric circuit for modeling liquid crystal microlenses. An interesting feature of the model is that it provides an analytical solution for microlenses with modal and hole-patterned electrode schemes, by using a simple software tool. The required driving scheme (modal or hole-patterned) can be predicted. These theories have been validated by experimental results. For more complex devices, the equations are solved by Finite Element Method. A new manufacturing protocol is proposed to make the first set of modal microlens arrays. As a first step simple devices (monopixel cells) are fabricated in order to do a complete study of the liquid crystal electro-optical behavior. The characterization of the liquid crystal electro-optical parameters is determinant in order to design more complex devices. Refractive index and permittivity are the most important features considered. These parameters have been characterized to validate the proposed theoretical modelling of the liquid crystal molecular position. These devices have required special fabrication processes as well as a special characterization set-up especially in terms of size resolution or arrangement complexity. A custom micropositioner is developed and control software is programmed in relation to these tasks. The software automates the characterization process giving directly measured results of: phase modulation, focal distance, thickness or aberrations. These results have made it possible to validate experimentally the proposed electrical modeling for micro-optical devices. Demonstration of the viability of the liquid crystal lenticular technology has been carried out for an autostereoscopic application. This scheme provides the observer with the option of changing between horizontal and vertical views through his portable autostereoscopic display. Finally, last research contributions of this work of thesis have taken advantage of the deep knowledge of the electro-optical properties of lenticular devices for autostereoscopic applications, to guide the design of refined micro-optical phase modulators. Adaptive axicons and optical vortices are specially emphasized because their relevance from both, the scientific and technological point of view.Esta tesis se inició con el proyecto de investigación “Dispositivos avanzados de cristal líquido y diodos orgánicos electroluminiscentes. Aplicaciones híbridas para visión 3D”, financiado por el gobierno español. El objetivo de este proyecto consistía en el desarrollo de dispositivos ópticos para lograr visión 3D en dispositivos portátiles sin necesidad de gafas o elementos externos. Con el fin de alcanzar los objetivos de este proyecto, se consideran soluciones basadas en cristal líquido. En concreto, moduladores adaptativos de fase micro-ópticos basados en tecnología de cristal líquido. El gradiente del índice de refracción varía espacialmente el retardo de fase experimentado por un frente de onda incidente. Mediante el uso de este efecto, cualquier elemento óptico refractivo puede ser reproducido mediante un gradiente de tensión adecuado aplicado a la muestra. Este es el principio de funcionamiento de los moduladores de fase micro-ópticos propuestos en esta tesis. Como aportación original de esta tesis, se propone un nuevo algoritmo para resolver el director molecular de un cristal líquido nemático. Una vez que el cristal líquido está completamente caracterizado, es necesario el desarrollo de un modelo específico para saber la respuesta electro-óptica de los moduladores de fase micro-ópticos. Otra contribución original, consiste en un circuito eléctrico equivalente para el modelado de microlentes de cristal líquido. Una característica interesante del modelo es que proporciona una solución analítica para microlentes con esquemas de electrodos modales y “hole patterned”. Se puede predecir la topología necesaria en función de los parámetros de construcción. Estas teorías han sido validadas por resultados experimentales. Para los dispositivos más complejos, las ecuaciones se resuelven por el método de elementos finitos. Se propone un nuevo protocolo de fabricación para hacer microlentes modales. Como primer paso se fabrican dispositivos sencillos (células monopixel) con el fin de hacer un estudio completo del comportamiento electro-óptico del cristal líquido. La caracterización de los parámetros electro-ópticos de cristal líquido es determinante para diseñar dispositivos más complejos. El índice de refracción y la permitividad son las características más importantes. Estos parámetros se han caracterizado para validar el modelo teórico de la posición molecular de cristal líquido. Estos dispositivos han requerido procesos de fabricación complejos, así como montajes de caracterización determinados. Se ha desarrollado un microposicionador y un software de control. El software automatiza el proceso de caracterización dando resultados de: modulación de fase, distancia focal, grosor o aberraciones. Estos resultados han permitido validar experimentalmente el modelado eléctrico propuesto para dispositivos micro-ópticos. La demostración de la viabilidad de la tecnología propuesta se ha llevado a cabo mediante un dispositivo autoestereoscópico. Este dispositivo ofrece al observador la opción de cambiar entre vistas horizontal y vertical a través de su pantalla autoestereoscópica portátil. Finalmente, los últimos aportes de investigación de este trabajo de tesis se han aprovechado del profundo conocimiento de las propiedades electro-ópticas de los dispositivos lenticulares para aplicaciones autoestereoscópicas. Se pueden destacar los axicones adaptativos y vórtices ópticos por su relevancia tanto desde el punto de vista científico como tecnológico.Este trabajo ha sido desarrollado en el marco de los proyectos TEC2009-13991-C02-01 financiado por el Ministerio de Ciencia e Innovación y FACTOTEM2 S2009/ESP-1781 financiado por la Comunidad de Madrid.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Ignacio Raúl Matías Maestro.- Secretario: Antonia Isabel Pérez Garcilópez.- Vocal: Dimitrios C. Zografopoulo

Flight Avionics Hardware Roadmap

As part of NASA's Avionics Steering Committee's stated goal to advance the avionics discipline ahead of program and project needs, the committee initiated a multi-Center technology roadmapping activity to create a comprehensive avionics roadmap. The roadmap is intended to strategically guide avionics technology development to effectively meet future NASA missions needs. The scope of the roadmap aligns with the twelve avionics elements defined in the ASC charter, but is subdivided into the following five areas: Foundational Technology (including devices and components), Command and Data Handling, Spaceflight Instrumentation, Communication and Tracking, and Human Interfaces