Optical modelling of accommodative light field display system and prediction of human eye responses

The spatio-angular resolution of a light field (LF) display is a crucial factor for delivering adequate spatial image quality and eliciting an accommodation response. Previous studies have modelled retinal image formation with an LF display and evaluated whether accommodation would be evoked correctly. The models were mostly based on ray-tracing and a schematic eye model, which pose computational complexity and inaccurately represent the human eye population's behaviour. We propose an efficient wave-optics-based framework to model the human eye and a general LF display. With the model, we simulated the retinal point spread function (PSF) of a point rendered by an LF display at various depths to characterise the retinal image quality. Additionally, accommodation responses to rendered LF images were estimated by computing the visual Strehl ratio based on the optical transfer function (VSOTF) from the PSFs. We assumed an ideal LF display that had an infinite spatial resolution and was free from optical aberrations in the simulation. We tested images rendered at 0--4 dioptres of depths having angular resolutions of up to 4x4 viewpoints within a pupil. The simulation predicted small and constant accommodation errors, which contradict the findings of previous studies. An evaluation of the optical resolution of the rendered retinal image suggested a trade-off between the maximum resolution achievable and the depth range of a rendered image where in-focus resolution is kept high. The proposed framework can be used to evaluate the upper bound of the optical performance of an LF display for realistically aberrated eyes, which may help to find an optimal spatio-angular resolution required to render a high quality 3D scene.Comment: 24 pages, 12 figures, submitted to Optics Expres

Optical modelling of an accommodative light field display system and prediction of human eye responses

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Observed optical resolution of light field display: Empirical and simulation results

Light field (LF) displays are a promising 3D display technology to mitigate the vergence-accommodation conflict. Recently, we have proposed a simulation framework to model an LF display system. It has predicted that the in-focus optical resolution on the retina would drop as the relative depth of a rendered image to the display-specific optical reference depth grows. In this study, we examine the empirical optical resolution of a near-eye LF display prototype by capturing rendered test images and compare it to simulation results based on the previously developed computational model. We use an LF display prototype that employs a time-multiplexing technique and achieves a high angular resolution of 6-by-6 viewpoints in the eyebox. The test image is rendered at various depths ranging 0–3 diopters, and the optical resolution of the best-focus images is analyzed from images captured by a camera. Additionally, we compare the measurement results to the simulation results, discussing theoretical and practical limitations of LF displays.Peer reviewe

Subjective comparison of monocular and stereoscopic vision in teleoperation of a robot arm manipulator

Remote operation of robot manipulators plays a crucial role in various safety-critical application areas such as forestry, mining, surveillance, etc. The capture and display of visual information of the real operation environment in an information-rich way is one of the key factors in achieving effective and robust teleoperation capability. In this paper, through subjective experiments, we comparatively investigate the roles of monocular, i.e. 2D, and stereo capture and display systems in the context of teleoperation of a robot arm. In particular, the positioning task is considered and, for both monocular and stereoscopic cases, two different modes of capture are implemented, which are static capture setup separately located from the robot arm and dynamic capture setup positioned at the tip of the robot arm. The experiments, conducted on 10 subjects (aged 24-33), show that stereo vision systems enable significant increase in accuracy of positioning compared to conventional 2D capture and display cases. In average, the tasks are completed with highest accuracy in the case of dynamic stereo capture setup.publishedVersionPeer reviewe

Cocrystalline matrices for hyperpolarization at room temperature using photoexcited electrons

We propose using cocrystals as effective polarization matrices for triplet dynamic nuclear polarization (DNP) at room temperature. The polari-zation source can be uniformly doped into cocrystals formed through acid–acid, amide–amide, and acid–amide synthons. The dense-packing crystal structures, facilitated by multiple hydrogen bonding and – interactions, result in extended T1 relaxation times, enabling efficient polarization diffusion within the crystals. Our study demonstrates the successful polarization of a DNP-magnetic resonance imaging molecular probe, such as urea, within a cocrystal matrix at room temperature using triplet-DNP