This PDF file contains the front matter associated with SPIE Proceedings Volume 10942, including the Title Page, Copyright information, Table of Contents, Introduction, Author and Conference Committee lists

Near-eye displays with focus cues attract a lot of attention from display society since they can provide more immersive and comfort experience. However, there are several challenging issues to implement near-eye displays with focus cues. First, most prototypes still suffer from the contrast or resolution degradation which is drawback in reconstructing continuous focus cues. Second, providing multiple focus cues usually involves complex or large optical design that prevent comfort experience. Third, rendering process for layered structures demands a large computation load so that it is hard to realize real-time operation. Here, we will investigate several ideas to solve or mitigate these challenges. Foveated retinal optimization enhances the central contrast by considering human visual characteristics. After a calibration process, foveated retinal optimization could be employed without a gaze tracking system because pupil location, gaze direction, and distribution of optical nerves are correlated. Hybrid multi-layer displays are a convincing approach to achieve advantages of additive and multiplication displays. Combining additive and attenuated layers, hybrid multi-layer displays have relatively small form factor and higher brightness while providing continuous focus cues within the range of 1.8 diopter. Recently, we conceived a novel prototype that supports a large number of layers within the large depth of field. This system provides semi-original contrast, large depth of field, and quasi-continuous focus cues at 60 frames per second. We believe this approach may open a new possibility for near-eye displays for representation of continuous depth.

Augmented reality (AR) technology is a hot topic research field in recent years. It combines the real world scene and virtual 2D or 3D images. We propose two AR 3D display systems based on integral imaging (II) by using a micro-lens array holographic optical elements (HOE). In the first AR display system, we realize a dual-view-zone 3D display based on angle multiplexing technology. In recording process, two parallel beams with different incident angles illuminate a micro lens array (MLA) to form two sets of inclined spherical wave arrays, and another parallel beam illuminates the opposite side of the photopolymer. After exposure, the MLA-HOE is fabricated. In reconstruction process, only the Bragg matched light can be diffracted, while the Bragg mismatch light transmits through the HOE directly. Thus, when a projector beam satisfies the Bragg match condition, two inclined spherical wave arrays with the different diffraction directions will be rebuilt to realize the dual-view-zone AR 3D display. In the second AR display system, we improve the resolution of the AR 3D display by using a lenticular lens array HOE. In this system, we use a divergent light as the reference beam to simplify the display system and enlarge the display size of the HOE. The AR 3D display system has enhanced resolution and is compact.

The optimum liquid crystal display (LCD) mode and moving-picture characteristics that are required by virtualreality head-mounted displays (VR-HMDs) are reported. To drive the LCD at 120 Hz and with 2432 gate lines, the response time of the LCD must be less than 2.4 ms when the time allocated to address the input data is 5.27 ms and the time required to emit a backlight is 0.66 ms. In this study, fast responses were achieved by using short-range lurch control in-plane switching (SLC-IPS). The orthogonal distance between the two non-responsive regions to the liquid crystal layer thickness affects the response of the liquid crystal display mode, which was controlled by using a simple electrode structure. The SLC-IPS obtained by this structure exhibits a response that is approximately three times faster than that of a conventional IPS. We designed an LCD that incorporates the SLC-IPS mode by using a trunk-and-branch electrode structure. However, because the liquid crystal of the trunk does not rotate, it causes an issue in terms of transmittance; thus, we adopted a one-sided branched structure with a modified trunk to solve this issue. Consequently, we were able to demonstrate a high-definition and fast-response LCD that is suitable for use in VR-HMDs. The response time of the LCD reached 2.2 ms, meeting the required 2.4-ms benchmark for optimal LCD performance.

We introduce mini-LED as a promising solution for high dynamic range displays. For mini-LED backlit local dimming LCD, we build a model to simulate the displayed image quality. Through modeling and subjective experiments, we demonstrate that the annoying halo effect could be suppressed to an unnoticeable level by appropriately choosing local dimming zone number and LCD contrast ratio. For mini/micro-LED emissive displays, we discuss the ambient excitation/reflection issues for the two typical full-color solutions and the corresponding size effect. The high luminance and excellent dark state, low power consumption and thin profile, long lifetime and free form factors will make mini- LED displays the next-generation high dynamic range solutions.

We report a polarization-multiplexed additive light field display for near-eye applications. A polarization-sensitive Pancharatnam-Berry phase lens is implemented to generate two focal depths simultaneously. Then, a spatial polarization modulator is utilized to control the polarization state of each pixel and direct the two images to designated focal planes. Based on this design, an additive light field display system is constructed. The vergence-accommodation conflict is suppressed successfully without increasing space and time complexities.

A fundamental cause of visual discomfort in traditional head-mounted displays (HMDs) for Virtual and Augmented Reality (VR/AR) is the vergence-accommodation conflict (VAC).We propose and develop a novel headset prototype based on the Verifocal^TM platform to eliminate VAC by dynamically adjusting the focal plane of the display. The developed headset employs an eye tracking system to track the user's gaze and determine the virtual object being observed by the user. The varifocal display then moves the focal plane of the display to dynamically match the depth of the observed object, providing correct focus cues to the user. We achieve the focal plane adjustment by moving the headset's stereo displays independently using small, lightweight and low-power piezoelectric actuators. Such actuators offer a very low response time with high positional accuracy, while operating at a high speed and virtually silently. Furthermore, our headset prototype has a large adjustable dioptric range for each eye and thus provides the capability for also correcting myopia and anisometropia, allowing vision-impaired users to use the headset without the need for eyeglasses. In conclusion, our approach makes it possible for the user to observe close or far objects in the virtual environment with reduced eye strain by providing consistent depth cues for all viewing distances.

LightSpace Technologies have developed a prototype of integrated head-mounted stereoscopic display system based on a proprietary multi-plane optical diffuser technology. The system is entirely solid-state and has six focal planes which covers ~3 diopters (from 32 cm to 8 m). For the operation no eye-tracking is utilized. The new display system virtually entirely eliminates vergence-accommodation conflict and adds a monocular accommodation as an important depth cue for improved 3D realism. In regards to content rendering the processing load in contrast to conventional single-focalplane stereoscopic displays with similar image resolution is only slightly increased. The differences in terms of comparative performance are the worst in the case of simple 3D scenes, while for high-complexity scenes this difference has a tendency to slightly decrease. On average the processing burden for multi-plane stereoscopic displays is no more than 1.5% higher than for conventional stereoscopic displays. Furthermore, increasing a number of physical focal planes doesn’t notably worsen the image rendering performance allowing the display device to be efficiently driven by already readily available hardware – including high-performance mobile platforms. Overall, the user feedback about the developed multi-plane stereoscopic 3D display prototype confirms prior proposed assumptions of multi-plane architecture yielding higher acceptance rate due to improved 3D realism and eradicated vergence-accommodation conflict, thus currently being one of the most noteworthy advancements in the field of 3D stereoscopic displays.

Stereoscopic augmented reality (AR) displays with a fixed focus plane suffer from visual discomfort due to vergenceaccommodation conflict (VAC). In this study, we propose a biocular dual-focal plane AR system. Two separate liquid crystal displays (LCDs) are placed at slightly different distances to a Fresnel relay lens such that virtual images of LCDs appear at 25 cm and 50 cm to the user. Both LCDs are totally viewed by both eyes, such that the rendered images are not parallax images for each eye. While the system is limited to two depths, it provides correct focus cues and natural blur effect in two distinct depths. This allows the user to distinguish virtual information, even when the virtual objects overlap and partially occlude in the axial direction. Displays are driven by a single computation unit and the objects in the virtual scene are distributed over the LCDs according to their depths. Field-of-view is 60 x 36 degrees and the eye-box is larger than 100 mm, which is comfortable enough for two-eye viewing.

Although the promise of realizing lower cost fabrication by means of solution-based processing techniques, such as spin coating, web coating or inkjet printing, has been one key driver behind the interest in OLEDs for the last two decades, the lower stability of devices made by these techniques has been a long-standing issue. With recent advances in developing solution-processable small molecule materials, it is now possible to make OLEDs of the same small molecule materials by either solution coating or vacuum deposition. Despite this, there continues to be an intriguing stability gap. In this work, we investigate this phenomenon with the purpose of identifying its root causes. Photoluminescence, electroluminescence and delayed electroluminescence measurements are used to study and compare between the aging behaviour in OLEDs made by spin-coating versus vacuum-deposition. Hole-only devices are also utilized, and employed to study the effects of charges and excitons, separately and combined. The results reveal that solution-coated materials are more susceptible to degradation by excitons in comparison to their vacuum-deposited counterparts. Results also show that they are more susceptible to aggregation under electrical stress, and that interactions between excitons and polarons play a role in this phenomenon. Results from these investigations will be presented and discussed.

Solution-processed polymer light-emitting diodes (PLEDs) have been widely investigated in display area due to their low-cost and large-scale fabrication. Generally, in order to pattern the device, the electrodes are deposited through a vacuum process such as sputtering or thermal evaporation. In terms of cost, inkjet printing is the most promising alternative to evaporation process because it allows low-material consumption as well as free patterning of the electrodes. However, direct inkjet-printing on the organic layers induces solvent permeation, which causes severe damage to underlying layers. In addition, fine patterns are hard to be obtained because the surface treatment on the functional layers is limited. In this research, we report solution-processed PLEDs with inkjet-printed electrodes. In order to prevent solvent permeation and obtain fine patterns by inkjet printing, we print top electrode on surface-modified polydimethylsiloxane (PDMS) substrate and laminate it on the organic functional layers. A structure of our devices is ITO (anode) / PEDOT :PSS (HIL) / PDY-132 (EML) / PEI (interlayer) / ZnO (EIL) / Ag (cathode). The device with laminated Ag shows a turn-on voltage of 2.7 V at 1 cd/m2 and a current efficiency of 7.8 cd/A at 1000 cd/m2, while the device with evaporated Ag shows 2.4 V and 9.9 cd/A under the same condition. Based on our lamination process, all solution-processed PLEDs are fabricated by replacing ITO to inkjet-printed PEDOT :PSS. Furthermore, passive-matrix application is demonstrated showing the possibilities of all solution-processed display. Detailed fabrication process and experimental results will be discussed at the conference.

Organic light-emitting diodes (OLEDs) have been successfully applied as displays and also recognized as a next-generation lighting technology because their several advantages such as self-emission, high luminous efficiency, full-color capability, wide viewing angle, high contrast, low power consumption, low weight, large area manufacture, transparence and flexibility. Now, the red and green phosphorescent OLEDs are qualified for the commercial products. The bottleneck still is the blue OLED. Currently, the high efficiency (100% internal quantum efficiency, and over 20% external quantum efficiency, EQE) blue OLED can be achieved using phosphorescent and thermal activated delay fluorescent (TADF) emitters, which were the crucial factor to determine color purity, efficiency, and lifetime of device. Beside the emitters, the other important factor is the host material. In this talk, we synthesized several novel carbazole-based, benzimidazole-based, and their combined derivers to be the universal hosts with wide energy bandgap for red, green, blue phosphorescent emitters and also applied for green and blue TADF emitters. These novel host materials could be classified as electron transport, hole transport, and bipolar. The carrier dynamics in OLEDs with these host materials were investigated by probing the position of main recombination zone and optimizing the efficiency performance. With increasing electron mobility of host material, the main carrier recombination zone in emitting layer was moved from the ETL side to the HTL side. Finally, the high EQE of over 30% was achieved in green and blue phosphorescent and TADF OLEDs with our host system. In addition, the operational lifetime was also improved by using our host system, comparing that of OLED with commercial mCP host.

Triplet-triplet annihilation provides a way to generate stable, high energy (blue) emission from organic light-emitting diodes via the fusion of low energy triplet excitons. Low energy sensitizers can be used to populate the triplet states of the emitter, which allows low voltages can be used. However, these same sensitizers can also quench the emission of the high energy singlet in the emitter layer. Managing the motion of triplet excitons by adding a triplet-diffusion-singlet-blocking layer allows us to decouple the sensitization and emission events, preventing singlet quenching and enhancing the blue emission by a factor of 10 or more.

Organic light emitting diode (OLED) has lots of advantages in display technology such as self-emissive, light-weight, and compatible for flexible substrates. Compared to the red and green OLEDs, blue one has shorter lifetime due to high-energy polaron quenching. Triplet-triplet annihilation up conversion (TTAUC) is a promising way to reduce the driving voltage and improve the operation lifetime for a blue OLED. This system includes two materials, sensitizer and emitter, which has a narrower bandgap and triplet-triplet annihilation (TTA) characteristic, respectively. When the sensitizer is excited, its triplet exciton can transfer the energy to the triplet of emitter with lower triplet energy and fuse into one singlet exciton with a higher energy photon than the sensitizer. In this research, we demonstrate that a convention green fluorescent material, tris(8-hydroxyquinolinato)aluminum (Alq3) can be used as a sensitizer for a blue TTA emitter, 9,10-Bis(2-naphthyl)anthraces (ADN). In a conventional Alq3-based OLED, when the electron and hole coming from cathode and anode recombined at Alq3 as the recombination layer, 25% of singlet and 75% of triplet were generated. All triplet exciton experienced non-radiative recombination, which resulted in low efficiency due to the poor reverse intersystem crossing (RISC) rate. On the other hand, in TTAUC-OLED, triplet exciton of Alq3 (ET=2.0 eV) transferred the energy to the triplet of ADN (ET=1.67 eV) via Dexter energy transfer and two of them fused into one singlet (ES=2.83 eV) with blue emission. This recycled the useless triplet exciton and resulted in a higher external quantum efficiency (EQE) for TTAUC-OLED (2.1%) compared to the Alq3 (1.2%) and ADN (1.67%) control devices. Moreover, the recombination zone was shifted from ADN to Alq3, the operation lifetime of blue component can be increased by 3x times longer than the ADN control device. From transient electroluminescence (TrEL) measurement, Alq3-control device showed a fast decay within 1us which implied only singlet exciton involved. For the TTAUC-OLED, blue emission showed only delayed component which meant the emission came from only TTA process without direct recombination.

We fabricated all solution-processed inverted polymer light emitting diodes (PLEDs) where functional layers were spin-coated on patterned-ITO glass substrates and PEDOT:PSS anodes were deposited by a transfer process. The structure of our devices is ITO (cathode) / ZnO (EITL) / PEI (interlayer) / PDY-132 (EML) / PEDOT:PSS (HITL) / transferred conductive PEDOT:PSS (anode). Although many groups have studied all solution-processed PLEDs, top electrodes were typically fabricated by photolithography or adhesive tape, which hinders low-cost and large-area mass production. In order to fabricate top electrodes which will not damage underlying organic layers and can be implemented in a facile manner, we used the transfer process. PEDOT:PSS was selected as the top electrodes because it can be patterned by a printing process such as an inkjet printing technique, and then the patterned PEDOT:PSS electrodes can be easily transferred. We fabricated two types of inverted PLEDs which have an evaporated Al or a transferred PEDOT:PSS top electrode. The device with the evaporated Al showed a turn-on voltage of 2.6 V defined at 1 cd/m2 and a current efficiency of 10.2 cd/A at 1000 cd/m2 while the one with the transferred PEDOT:PSS showed a turn-on voltage of 2.7 V and a current efficiency of 8.2 cd/A at the same condition. Difference in sheet resistance of the top electrode and thus, charge balance change probably caused the performance variation. When the bottom cathodes are inkjet-printed, all solution-processed inverted PLEDs can be implemented, which will be also presented at conference.

Ultra-realistic virtual object representation is an old dream of humanity. From the 3D Paleolithic rock painting to the late Michael Jackson holographic shows, humans have investigated display solutions to give life to the abstraction. The incredible opportunities given by the digital revolution have paved the way to the recent development of innovative volumetric displays. These complex solutions are however still limited in the visual experience they can offer to the viewer. In a more concerning manner such devices often appear as empty shells as their effective usefulness is not yet clearly defined. Recently, we have proposed an original volumetric display concept based on a 360° projection configuration. Inspired from the pepper ghost concept and from the praxinoscope design of the end of the XIX century, our display mixes real projection on transparent retroreflective surface and virtual images superimposition. This development has been made in collaboration with a group of live performing artists in France. The 360° display has been used to present an original creation of the artists and the confrontation with the public has highlighted some unexpected properties of this family of displays. We describe here the technological concept of our display and the evolutions we target to improve the visual rendering. The collaboration project with the artists is also presented and we give our analysis on the feedback of the public.

It is a challenge for conventional projectors to conduct projection mapping for a 3D dynamic moving object along the depth direction, due to the limitation of their narrow depth-of-field. Here, a dynamic projection system is proposed that has overcome the above limitation by employing a liquid-filled variable focal unit and a depth-sensing module. The depth sensor detected the depth information of the projection target, and then served as feedback to adjust the focal length of the variable focal lens, in turn, the focal length of the projection system would be controlled. A well-focused projection mapping with a randomly moving object would be demonstrated.

Visual displays simplify our hyperspectral world into three channels (RGB), controlling the activity of cone photoreceptors. Recent data show that a new photoreceptor in the human eye – melanopsin – also contributes to visual perception. Current image capture and display technologies, however, do not account for this new dimension of vision. We have addressed this deficit, and have applied our updated understanding of vision to develop new, biologically relevant methods of image capture, processing and display. Here, we describe a multi-primary display that controls melanopic activity independently of chromaticity and luminance. We have used this device to present images varying in their relative melanopic activity, and have asked naïve participants to judge differences between images. We find that regulating this additional melanopic dimension improves the appearance of images matched in chromaticity and luminance. In sum, including a melanopic dimension could represent a new approach to improving the quality of image capture and displays.

We have previously proposed eye tracking system to expand viewing area in all directions for glasses-free 3D display. In this system, since the parallax barrier was fixed, the viewing zone was expanded by image processing corresponding to the viewing position. Thus, there was a limit to expanding the viewing zone only by image processing. On the other hand, we can expand the viewing zone by applying an active barrier that changes to the optimum barrier pattern corresponding to the viewing position by eye tracking. However, to change the active barrier pattern, complex calculation and a specially designed active barrier LC panel are required. To overcome this problem, we propose a novel control method to expand the viewing zone of stereoscopic 3D displays with active parallax barrier in depth direction. The proposed method is the combination of the simple generation method of a barrier pattern and the synthesis method of Left/Right synthetic image corresponding to the viewing position. In this method, let the optimum barrier pitch be Bp at the viewing distance d, we set the barrier pitch to x*Bp and synthesize the Left/Right image so that crosstalk is low at the same time at the viewing distance d/x. To verify the effectiveness of the proposed method, we measured the crosstalk of the prototype 3D display. The crosstalk ratios at the optimum viewing distance 1092 mm (d), 774 mm (d*3/4) and 546 mm (d*1/2) were 4.28%, 3.82% and 5.02%, respectively. Therefore, low crosstalk 3D images could be observed.

We propose a novel technique to synchronize elemental images and audio signal and the transmission technique for a glass-free 3D TV system based on integral imaging. The main idea behind the method is to generate 3D video based on elemental images synchronized with audio stream. The system uses the depth information and RGB data of per frame of a video through Intel RealSense 3D camera and the audio stream from microphone. The audio file is sampled according to per frame duration of the video and kept in different buffers but having same index. The frames are divided into elemental images using Elemental Image Generation algorithm and the audio signal is synchronized according to the index. Then the stream of elemental images and corresponding audio data is transmitted to data server for storage. HLS streaming protocol is used to stream the TV content. A dedicated web application was made that fetches data from the server and plays video on the user end display device. By using array of micro-lenses in front of display, the video is viewed as three-dimensional with the help of integral imaging technology that omits the need of wearing 3D glasses.

An improved and efficient system for faster computation of Elemental Image generation for real time integral imaging 3D display system with the assistance of Graphics Processing Unit parallel processing is proposed. Previously implemented systems for real time integral imaging system had a resulting frame rate greater than 30 fps for elemental image generation. But this improved and more efficient system is able to produce elemental image at a rate greater than 65 fps for real time integral imaging system. Our proposed model consists of the following steps: information acquisition of objects in real time using Kinect sensor, generation of elemental image sets using pixel mapping algorithm using GPU parallel processing for faster generation. To implement this system, firstly the color (RGB) and depth information data of each object point is acquired from the depth camera (Kinect sensor). Using acquired information, we create the elemental image sets using pixel mapping algorithm. And finally we implemented the pixel mapping algorithm in GPU and hence the overall computational speed of the real time integral display system increased surprisingly. This remarkable increase in speed for elemental image generation opens up new field of possibilities for improvement in integral imaging technology i.e. merging this system with multi-directional projection for real time integral imaging system can enhance the viewing angle remarkably and so on.

In this paper, we propose the well-enhancing method for the resolution of the reconstructed image of the mobile threedimensional integral imaging display system. A mobile 3D integral imaging display system is a valuable way to acquire the 3D information of real objects and display the realistic 3D visualizations of them on the mobile display. Here, the 3D color and depth information are acquired by the 3D scanner, and the elemental image array (EIA) is generated from the acquired 3D information virtually. However, the resolution of the EIA is quite low due to the low-resolution of the acquired depth information, and it affects the final reconstructed image resolution. In order to enhance the resolution of reconstructed images, the EIA resolution should be improved by increasing the number of elemental images, because the resolution of the reconstructed image depends on the number of elemental images. For the comfortable observation, the interpolation process should be iterated at least twice or three times. However, if the interpolation process is iterated more than twice, the reconstructed image is damaged, and the quality is degraded considerably. In order to improve the resolution of reconstructed images well, while maintaining the image quality, we applied the additional convolutional super-resolution algorithm instead of the interpolation process. Finally, the 3D visualizations with a higher resolution and fine-quality are displayed on the mobile display.

We fabricated solution-processed transparent silver nanowires (AgNWs) electrodes and applied them to anodes of polymer light-emitting diodes (PLEDs). While patterning methods of the AgNW electrodes in previous research were rather expensive and complicated, we used a transfer method. The AgNW electrodes were fabricated by transferring AgNWs from polydimethylsiloxane (PDMS) stamp to inkjet-printed poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) without lithographic patterning. However, due to the rough surface property of the AgNWs placed on the PEDOT:PSS film, AgNW/PEDOT:PSS electrodes cannot be directly employed as the bottom electrode of PLEDs. Therefore, to reduce the surface roughness, they were embedded onto ultraviolet-curable photopolymer, enabling the PEDOT:PSS films to be placed on the AgNWs. The embedded PEDOT:PSS/AgNW electrodes exhibited a sheet resistance of 18.4 Ω/sq and transmittance of 85.6 % at the 550 nm wavelength, which were comparable with those of indium tin oxide (ITO). In addition, the surface roughness of embedded electrodes decreased from 26.8 nm to 11.8 nm in root-mean-square value. We fabricated the PLEDs with the embedded anode, which have a structure of anodes / PEDOT:PSS (HIL) / PDY-132 (EML) / LiF / Al (cathode) on the PEN substrates. As a result, the PLEDs with the embedded anodes showed a current efficiency of 7.1 cd/A and a power efficiency of 2.9 lm/W at 1000 cd/m2. Furthermore, they operated well under a constant current due to reduction of surface roughness without the high leakage current. The mechanical property of embedded AgNWs-transferred PEDOT:PSS electrodes and optimization of PLEDs with them can be presented at conference.

Printing technologies based on plasmonic structures have been intensively studied for their great advantages over organic colors and pigments. However, metallic nanoparticles have inherent plasmon damping and possess mainly electric-like resonances, thus there exists an urgent need for another degree of controlling the structural colors, for example the magnetic resonance modes. Here we propose truncated cone shaped silicon metasurfaces and numerically simulate their reflection characteristics. The designed metasurfaces are based mainly on magnetic Mie resonances because the strength of electric resonances is negligibly small compared with that of magnetic resonances. From numerical simulation, the intensity of the reflection peak reaches almost 90% and the full width at half-maximum (fwhm) of reflectance spectrum is 43nm. More detailed numerical analysis shows that distinct colors can be obtained giving a spatial resolution around 85000dpi. Specific colors with saturation close to 1 are available by selecting appropriate geometric dimension and period of the structure, which indicate the great application perspective of the proposed metasurfaces to produce well-defined colors covering the entire visible spectrum. The advantages of the designed metasurfaces are polarization-independence, cost-effective, stable, sustainable and CMOS(Complementary Metal Oxide Semiconductor)-compatible. Furthermore, the proposed structure works with a low aspect ratio of 0.46, which largely relieves the difficulty of process manufacturing.

Optical combiners are see through optical components, which fuse a virtual image with the real-world scene, and play a key part in near-to-eye (NTE) visors and head-up displays (HUDs). Several types of optical combiners have been demonstrated in the past^1,2. A common combiner scheme consists of a diffraction grating that couples light in and out of a planar waveguide. This combiner is durable, relatively easy to manufacture, and can project high-resolution images. Projecting a full color image, however, is challenging due to large chromatic aberrations, and requires more complex design schemes. In this work, we present an optical combiner, which is based on a planar waveguide with embedded multilayered plasmonic metasurfaces, serving as achromatic diffractive grating couplers. The multilayered metasurface grating couplers are ultra-thin (<500nm) and highly transparent (~90%). We fabricated 1mmX1mm metasurface based gratings using a standard E-beam lithography technique. The grating is designed to diffract only a specific wavelength range in the visible spectrum. Thus, it is possible to stack three layers of such metasurface gratings and couple a full color (RGB) image into a single waveguide, while compensating for the inherent chromatic dispersion of diffractive grating couplers.

We have previously proposed the retinal projection type super multi-view head-mounted display (HMD) using the time division projection optical system. By using the super multi-view HMD, it is possible to provide the viewer with the threedimensional (3D) image that induces the accommodation of a human eye naturally. In order to realize the super multi-view method, it is necessary to simultaneously project multiple parallax images on the retina. However, when the parallax between each parallax image is large and the corresponding pixels of each parallax image on the retina do not overlap each other, the retinal image is observed as multiple projection images, therefore the accommodation cannot be induced. In this paper, to estimate the displayable range of 3D image of the proposed super multi-view HMD, we revealed the relationship between the number of parallax images and the displayable range of 3D image by using Gullstrand’s schematic eye model and the analysis of the light intensity distributions of retinal images. In order to verify the displayable range of 3D image, we constructed the prototype HMD which projected five parallax images on the retina. We confirmed that the displayable range of 3D image of the prototype HMD is from 900 mm to 2000 mm in front of human eye. By clarifying the relationship between the number of parallax images and the displayable range of 3D image, it is possible to freely design the display range of 3D image of the retinal projection type super multi-view HMD.

Recently, three-dimensional (3D) display technologies actively have been researched for improving the quality of 3D display and for reducing 3D sickness such as the vergence-accommodation conflict. One of approaches is super multiview (SMV) display in which more than two views enter the pupil of the eye. We invented a time-sequential SMV theater system which is able to change the number of views entering the pupil. The SMV display consists of the projection part and the observation part. The projection part contains a light engine to realize full-color images by using three digital micro-mirror devices (DMDs). The image projected at the screen is observed through the observation part. The optical system functions as defining the direction of the optical rays acquired by the eyes according to the position of the opening. We implement this opening by using a DMD and the movement of the opening is realized by changing the slit patterns on the DMD. Two DMDs are synchronized to each other and the projection image is selectively observed by the predetermined position of the opening sequentially. In our system, the observation part is designed the observer to wear the device and this system is expected to have a potential to provide SMV to the audience in the theater.

Recently, augmented reality (AR) systems using holographic optical elements are getting the limelight. The holographic diffuser can be used as a screen in AR systems because it only diffuses incident light in a certain angle. To achieve a wide field-of-view (FOV), a diffusing angle of the screen should be sufficiently large. However, in the case of the holographic diffuser, it is difficult to achieve a high transmittance when the diffusing angle of the employed diffuser is large. In other words, by using conventional holographic screens, it is difficult to achieve a high transmittance and a wide FOV simultaneously. In this work, we propose an anisotropic holographic diffuser providing a wide FOV with relatively small diffusing angle by adopting a convex lens in the recording process. Furthermore, in the last section, a scheme of AR near-eye display system is suggested by using the proposed holographic screen and a special eye piece consisted of geometric phase lens.

In the stereoscopic 3D display using the parallax barrier, the active barrier method can expand the viewing area if the barrier pattern optimizes corresponding to the position of the observer by eye tracking. However, requiring not only the LC display panel but also the specially shaped LC panel for the active barrier, this system should be very expensive. We propose using the active barrier which is a monochromatic panel of the same pixel shape as the image display panel. In the proposed method, it is easy to manufacture panels for the active barrier, and the 3D display provide the wide viewing area and high quality 3D images for observers. When the active barrier is a monochromatic panel having the same pixel shape as the image display panel, basically the barrier pitch cannot realize the ideal value. Thus, the observer cannot observe the stereoscopic image in the full screen. In order to realize stereoscopic observation, we apply the cycle pitch composing the stereoscopic image. The cycle pitch composing the stereoscopic image is the method to bring the pitch constituting the L/R image closer to the ideal value by periodically increasing the number of dots constituting the L/R image. To confirm the effectiveness of the proposed method, the crosstalk of the prototypes using film barriers were measured. Crosstalk was less than or equal to 10% at the viewing distance of 421 mm to 1238 mm. That crosstalk can be reduced regardless of observation distance was confirmed.

We have investigated AC inorganic electroluminescence devices, where chlorine-functionalized carbon nanotubes (Cl- CNTs) were incorporated in the dielectric layer. At the concentration of 0.01 wt% of Cl-CNTs, roughly 50% increment in the luminance was observed, while maintaining a 30% reduction in the current density. It was further supported by the separate measurement of dielectric performance of the dielectric layers only, yielding to high dielectric constant and reasonably low dielectric loss for Cl-CNT incorporated layers. The enhancement in the dielectric constant is attributed to the micro-capacitor effect by space charge polarization at the interface between the phosphor layer and the dielectric layer. High polarization of C-Cl bonds within the dielectric layer is considered to promote the space charge polarization. To control the concentration of Cl-CNTs low is important in order not to cause percolation behavior of crisscrossing CNTs, which easily leaded to leakage current paths within the dielectric layer.

We proposed a three-dimensional (3D) holographic waveguide-type augmented reality (AR) system based on integral imaging using the mirror array. As same with the conventional holographic waveguide, two holographic optical element (HOE) films are utilized as in- and out-couplers, that are located at the input and output parts of the waveguide. The main role of the in-coupler HOE is that reflecting the light beams come from the micro display into the waveguide, and out-coupler reflects the transmitted light beams through the waveguide to the observer eye. On the basic of the main advantages of conventional holographic waveguide structure such as the light-weight and thin-size, the proposed system has an additional critical advantage that the observer can see the realistic 3D visualizations reconstructed by the outcoupler HOE-mirror array (HOE-MA), instead of simple two-dimensional images, with the real-world scenes at same time. In the experiment, the AR feature has been successfully verified that the real-world scene and reconstructed virtual 3D image were observed simultaneously.

The relationship between the transmission distance and the number of Fresnel zone plate rings is evaluated. The influence of different transmission distance and the number of Fresnel zone-plate rings are analyzed. Their parameters of the best reconstructed image are obtained. A point light source is taken as an example, a phase-only spatial light modulator with the resolution of 3840×2160 pixels and the pixel interval of 3.74 μm is used for experimental verification. The numerical simulation and optical experiment results show that the optimal reconstructed image has a transmission distance of 200 mm. Meanwhile, the optimal Fresnel zone ring number is 8 under the same conditions. This study provides the optimal parameters for the spatial light modulators with different size.

PSDs are used for fast and precise beam position measurements in various applications such as scanner characterization and scanning probe microscopy. However, PSDs suffer from systematic position sensing errors at high temperatures, limiting the possible application fields for usage of PSDs. This paper investigates temperature dependency of PSDs and its compensation that enables the usability of PSDs in high temperature applications above 60°C. The proposed compensation scheme is explained by the diode leakage current model, which is extended to the given semiconductor device structure of the PSD. For the validation of the proposed method, an experimental PSD characterization setup has been used, showing that the proposed temperature compensation scheme reduces the temperature-induced relative position sensing error from 44.7 % down to 0.2 % for temperatures up to 95°C.