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Tangible virtual reality for product design
Published in Paulo Jorge Bártolo, Artur Jorge Mateus, Fernando da Conceição Batista, Henrique Amorim Almeida, João Manuel Matias, Joel Correia Vasco, Jorge Brites Gaspar, Mário António Correia, Nuno Carpinteiro André, Nuno Fernandes Alves, Paulo Parente Novo, Pedro Gonçalves Martinho, Rui Adriano Carvalho, Virtual and Rapid Manufacturing, 2007
As for now, electro-holography-based volumetric displays have become able to create 3D images by digitally controlling the distribution and visual properties of holographic elements (hogels) in the air. Hogels are actually holographic voxels, which are created by interference of coherent laser beams. Electroholography uses coherent laser light to produce a three-dimensional hologram. The holographic image is sensed exactly as a real object. Human eyes are able to converge and focus on the hogels appearing at different physical depths inside the volume. Therefore, viewing holographic images from different angles is much more convenient than of multiplexed images. In addition, the electronically generated holography allows natural interaction between a number of users and a three-dimensional mid-air projected image.
Fabrication technology for light field reconstruction in glasses-free 3D display
Published in Journal of Information Display, 2023
Fengbin Zhou, Wen Qiao, Linsen Chen
With the advent of a 3D world, people have become dissatisfied by the visual perception of 2D imagery. Creating a virtual 3D universe has been man’s dream for 150 years since C. Wheatstone first invented stereoscopy [1]. A virtual 3D image can be reconstructed by discretizing a continuously distributed light field and creating multiple views based on either ray-tracing method or wavefront approach. The term ‘light field' used here either refers to the light ray collection of a 3D scene from the perspective of geometric optics or to the amplitude and phase information of a wavefront in wave optics. With properly arranged views, 3D images with motion parallax and stereo parallax can be visualized by integrating an optical element with a flat panel. Different from other technologies including holographic display and volumetric display, light field 3D display has a compact form factor compatible with portable electronic devices. The function of the optical element in a light field 3D display is to modulate the phase information of light field and generate a finite number of views, while the display panel refreshes the amplitude information. Notably, the modulated phase information of a view in diffractive optics-based 3D display not only refers to the angular deflection, but also includes light intensity distribution, angular separation, and view shape. As illustrated in Figure 1, parallax barriers, lenticular lens arrays, microlens array, directional backlight, multi-layer LCDs and diffractive optical elements (e.g. diffractive gratings, metasurfaces, etc) have been extensively studied for creating multiple views.