Teleoperation requires both wide vision to recognize a whole workspace and fine vision to recognize the precise structure of objects which an operator wants to see. In order to achieve high operational efficiency in teleoperation, we have developed the Q stereoscopic video system which is constructed of four sets of video cameras and monitors. It requires four video channels to transmit video signals. However, four channels are not always available for a video system because of the limitation of the number of radio channels when multiple systems are used at the same time. Therefore we have tried to reduce the number of channels on this system by sending images from the right and left cameras alternately by field. In experiment 1, we compared the acuity of depth perception under three kinds of stereoscopic video systems, the original Q stereoscopic video system, the Q stereoscopic video system with two channel transmission, and the conventional stereoscopic video system. As the result of the experiment, the original Q stereoscopic video system enabled us to perceive depth most precisely, the Q stereoscopic video system with two channel transmission less so, and the conventional stereoscopic video system even less. In experiment 2, we compared the Q stereoscopic video system with two channel transmission to the original Q stereoscopic video system. The result showed that the operators were able to work more efficiently under the original Q stereoscopic video system than under the Q stereoscopic video system with two channel transmissions. In experiment 3, we compared the Q stereoscopic video system with two channel transmission to the conventional stereoscopic video system. It was found out in this study that the new stereoscopic video system we developed enabled operators to work more efficiently and to perceive depth more precisely than the conventional stereoscopic video system, although the number of channels for image transmission of this system was equal to that of the conventional stereoscopic video system.
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[Show abstract][Hide abstract] ABSTRACT: We present a novel foveated imaging system which consists of three major components: a foveated imager, a peripheral imager, and a 2D scanning sub-system. The foveated imager captures a narrow field of view (FOV) with high angular resolution to mimic the foveated region of interest (FRoI), and the peripheral imager captures a wide FOV with low angular resolution to provide the peripheral region for context. The scanning system, implemented with a single-element two-axis MEMS mirror, is capable of sweeping the FRoI across the entire FOV at a maximum speed of 100Hz. A bench prototype and experimental results are presented as verifications of our optical design concept and feasibility.
[Show abstract][Hide abstract] ABSTRACT: Conventional imaging techniques adopt a rectilinear sampling approach, where a finite number of pixels are spread evenly across an entire field of view (FOV). Consequently, their imaging capabilities are limited by an inherent trade-off between the FOV and the resolving power. In contrast, a foveation technique allocates the limited resources (e.g., a finite number of pixels or transmission bandwidth) as a function of foveal eccentricities, which can significantly simplify the optical and electronic designs and reduce the data throughput, while the observer's ability to see fine details is maintained over the whole FOV. We explore an approach to a foveated imaging system design. Our approach approximates the spatially variant properties (i.e., resolution, contrast, and color sensitivities) of the human visual system with multiple low-cost off-the-shelf imaging sensors and maximizes the information throughput and bandwidth savings of the foveated system. We further validate our approach with the design of a compact dual-sensor foveated imaging system. A proof-of-concept bench prototype and experimental results are demonstrated.
[Show abstract][Hide abstract] ABSTRACT: The development of compact imaging systems capable of transmitting high-resolution images in real-time while covering a wide field-of-view (FOV) is critical in a variety of military and civilian applications: surveillance, threat detection, target acquisition, tracking, remote operation of unmanned vehicles, etc. Recently, optical foveated imaging using liquid crystal (LC) spatial light modulators (SLM) has received considerable attention as a potential approach to reducing size and complexity in fast wide-angle lenses. The fundamental concept behind optical foveated imaging is reducing the number of elements in a fast wide-angle lens by placing a phase SLM at the pupil stop to dynamically compensate aberrations left uncorrected by the optical design. In the recent years, considerable research and development has been conducted in the field of optical foveated imaging based on the LC SLM technology, and several foveated optical systems (FOS) prototypes have been built. However, most research has been focused so far on the experimental demonstration of the basic concept using off the shelf components, without much concern for the practicality or the optical performance of the systems. Published results quantify only the aberration correction capabilities of the FOS, often claiming diffraction limited performance at the region of interest (ROI). However, these results have continually overlooked diffraction effects on the zero-order efficiency and the image quality. The research work presented in this dissertation covers the methods and results of a detailed theoretical research study on the diffraction analysis, image quality, design, and optimization of fast wide-angle FOSs based on the current transmissive LC SLM technology. The amplitude and phase diffraction effects caused by the pixelated aperture of the SLM are explained and quantified, revealing fundamental limitations imposed by the current transmissive LC SLM technology. As a part of this study, five different fast wide-angle lens designs that can be used to build practical FOSs were developed, revealing additional challenges specific to the optical design of fast wide-angle systems, such as controlling the relative illumination, distortion, and distribution of aberrations across a wide FOV. One of the lens design examples was chosen as a study case to demonstrate the design, analysis, and optimization of a practical wide-angle FOS based on the current state-of-the-art transmissive LC SLM technology. The effects of fabrication and assembly tolerances on the image quality of fast wide-angle FOSs were also investigated, revealing the sensitivity of these fast well-corrected optical systems to manufacturing errors. The theoretical study presented in this dissertation sets fundamental analysis, design, and optimization guidelines for future developments in fast wide-angle FOSs based on transmissive SLM devices.
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