Depth plane adaptive integral imaging system using a vari-focal liquid lens array for realizing augmented reality.

Augmented reality (AR) is an interactive experience of a real-world environment where the objects that reside in the real world are enhanced by computer-generated perceptual information. Despite its attractive features, AR has not become popular because of the visual fatigue that many people face when they experience it. Many methods have been introduced to solve this visual fatigue problem and one of these methods is an integral imaging system that provides images almost continuous viewpoints and full parallax. However, the integral imaging system, which uses a lens array with a fixed focal length, has limited depth of focus (DOF) range. As a result, images that are outside of the DOF range become distorted. In this paper, a vari-focal liquid lens array was fabricated and the optical characteristics of the lens array were evaluated. Using the vari-focal liquid lens array, the DOF range was extended and high-resolution images are realized without restriction of depth range in an AR system.

Novel biconvex structure electrowetting liquid lenticular lens for 2D/3D convertible display.

Recently, a planoconvex structure electrowetting lenticular lens capable of 2D/3D conversion through a varifocal property by an electrowetting phenomenon has been developed. However, even though it has a similar planoconvex structure to that of a commercial solid lenticular lens, comparable 3D performance could not be realized because the refractive index difference between nonconductive liquid and conductive liquid was not large. Therefore, the goal of the present study is to obtain better 3D performance compared to the conventional planoconvex structure by introducing a novel biconvex structure using ETPTA. The newly developed biconvex structure electrowetting lenticular lens showed greatly improved characteristics compared to the planoconvex structure: dioptric power (171.69D → 1,982.56D), viewing angle (26degrees → 46degrees), and crosstalk ratio (27.27% → 16.18%). Thanks to these improvements, a fine 3D image and a natural motion parallax could be observed with the biconvex structure electrowetting lenticular lens. In addition, the novel biconvex structure electrowetting lenticular lens was designed to achieve a plane lens state with a no voltage applied condition, and as such it could show a clean 2D image at 0 V. In conclusion, a novel biconvex structure electrowetting lenticular lens showed 2D/3D switchable operation as well as excellent 3D performance compared to a solid lenticular lens.

Electro-wetting lenticular lens with improved diopter for 2D and 3D conversion using lens-shaped ETPTA chamber.

In this paper, we introduce a method for improving the lens diopter of 2D/3D convertible devices using electro-wetting. For stable operation, an electro-wetting device requires high dioptric performance and this was achieved using bi-convex liquid-liquid-solid phases. 1-Chloronaphthalene with a refractive index of 1.633 was used as an oil phase to achieve high diopters. ETPTA (trimethylolpropane ethoxylate triacrylate), a UV-sensitive material with low chemical reactivity to the 1-Chloronaphthalene, was used as a chamber material. This resulted in a diopter of 3030D for high quality multi-view images without unstable oil movement or trembling. The ETPTA was molded on a 0.3mm thick glass substrate that was coated with UV adhesive (NOA 81). The maximum diopter capable of stable operation was 3425D. 2D and 3D conversion and parallax motion were demonstrated.

Effect of oil on an electrowetting lenticular lens and related optical characteristics.

While there are many ways to realize autostereoscopic 2D/3D switchable displays, the electrowetting lenticular lens is superior due to the high optical efficiency and short response time. In this paper, we propose a more stable electrowetting lenticular lens by controlling the quantity of oil. With a large amount of oil, the oil layer was broken and the lenticular lens was damaged at relatively low voltage. Therefore, controlling the amount of oil is crucial to obtain the required dioptric power with stability. We proposed a new structure to evenly adjust the volume of oil and the dioptric power was measured by varying the volume of oil. Furthermore, the optical characteristics were finally analyzed in the electrowetting lenticular lens array with a proper amount of oil.

Improving the performance of an electrowetting lenticular lens array by using a thin polycarbonate chamber.

In this paper, we used a thin polycarbonate (PC) chamber to improve the performance of an electrowetting lenticular lens array. The polycarbonate chamber changed the radius of curvature (ROC) of the oil acting as a lens, which increased the dioptric power of the liquid lens to 1666.7D. The increase in dioptric power required a reduction in the distance between the optical center of the lens and the display pixels under the chamber, which was accomplished by reducing the thickness of the chamber. The optimal thickness of the chamber was determined to be 0.5mm. Using this thin PC chamber, transmittance and viewing angle were measured and compared with an electrowetting lenticular lens with a conventional 1mm poly methyl methacrylate (PMMA) chamber was done. Crosstalk which degrades clear 3D images, is an inevitable factor in lenticular lens type multi-view systems. With the 0.5mm PC chamber, the viewing zone was expanded and the ratio of the crosstalk area was reduced, which resulted in a clear 3D image. The new method of depositing the electrode layer also ensured the uniform operation of the liquid lens array.

Depth plane adaptive integral imaging using a varifocal liquid lens array.

This paper proposes an enhanced integral imaging system with an electrically controllable image plane to address the issue of the limited depth problem in integral imaging. For implementation of the variable image plane, a varifocal liquid lens array and driving device are adopted instead of an ordinary solid lens array. The position of the central depth plane is varied by adjusting the focal length of the lens array. The proposed system enables matching between the object position and depth plane electrically, and thus an object moving from 5.15 to 11.72 cm is clearly displayed with this method.

Synchronization of the bidirectionally coupled unified chaotic system via sum of squares method.

This paper considers the synchronization problem of the bidirectionally coupled unified chaotic system. Many previous works require the assumption that the states of the system are bounded and their range are known. This assumption may not hold for arbitrary controllers, and thus, it is not suitable to make this assumption beforehand. Accordingly, we propose the novel control method for bidirectionally coupled unified chaotic system via sum of squares method without this assumption. Numerical simulations show the validity and advantage of the proposed method.