Electrophoretic display (EPD) has been widely used in e-paper applications because of its flexibility, low power consumption, good sunlight visibility. The commercial success of monochromic EPD has boosted the development of full- color EPD to further satisfy people’s demand for various applications. However, many challenges shall be overcome before commercializing it. In this paper, we will introduce the EPD’s fundamental operation, the design of driving waveform for optimizing the opto-electronic performance, and the strategies for achieving full-color EPD as well as a color EPD prototype fabricated by transfer method.

A novel approach for RGB semiconductor LED-based backlighting system is developed to satisfy the requirements of the Project LUMENTILE funded by the European Commission, whose scope is to develop a luminous electronic tile that is foreseen to be manufactured in millions of square meters each year. This unconventionally large-area surface of uniform, high-brightness illumination requires a specific optical design to keep a low production cost, while maintaining high optical extraction efficiency and a reduced thickness of the structure, as imposed by architectural design constraints. The proposed solution is based on a light-guiding layer to be illuminated by LEDs in edge configuration, or in a planar arrangement. The light guiding slab is finished with a reflective top interface and a diffusive or reflective bottom interface/layer. Patterning is used for both the top interface (punctual removal of reflection and generation of a light scattering centers) and for the bottom layer (using dark/bright printed pattern). Computer-based optimization algorithms based on ray-tracing are used to find optimal solutions in terms of uniformity of illumination of the top surface and overall light extraction efficiency. Through a closed-loop optimization process, that assesses the illumination uniformity of the top surface, the algorithm generates the desired optimized top and bottom patterns, depending on the number of LED sources used, their geometry, and the thickness of the guiding layer. Specific low-cost technologies to realize the patterning are discussed, with the goal of keeping the production cost of these very large-area luminaries below the value of 100$/sqm.

We explain the technical bases of the Fourier Optics Technology (OFT) for viewing angle measurement of displays and the increasing capacities of the ELDIM systems over the years. A new generation of OFT systems devoted to quality control is introduced. In spite of a more compact size, the optic shows excellent performances in terms of angular aperture, angular resolution and collection efficiency. The detection is made with a new generation high resolution CMOS camera which allows very short measurement times. In addition, the probe can be used on a robotic arm to offer a cost effective solution for quality control of displays with any kind of size and shape.

Quantum dots (QDs) have gone through a long journey before finding their ways into the display field. This talk will briefly touch on the history before trying to answer several key questions related to QDs applications in display: What are QDs? How are they made? What properties do they have and Why? How can these properties be used to improve color and efficiency of display, in either photoluminescence (PL) or electroluminescence (EL) mode? And what are the remaining challenges for QDs wide adoption in display industry? Lastly, some most recent progresses in our UCF lab at both PL and EL fronts will be highlighted. For PL, a cadmium-free perovskite-polymer composite films with exceptionally narrow emission green peaks (FWHM ~20 nm) and good water and thermal stability will be reported. Together with red quantum dots or PFS/KSF phosphors as down-converters for blue LEDs, a white-light source with 95% Rec. 2020 color gamut was demonstrated [1]. For EL, red quantum dot light emitting devices (QLEDs) with record luminance of 165,000 Cd/m2 has been obtained at a current density of 1000 mA/cm2 with a low driving voltage of 5.8 V and CIE coordinates of (0.69, 0.31). [2] The potential of using these QLEDs for light sources for integrated sensing platform [3] or high efficiency, high color quality hybrid white OLED [4] will be discussed. [1] Y. N. Wang, J. He, H. Chen, J. S. Chen, R. D. Zhu, P. Ma, A. Towers, Y. Lin, A. J. Gesquiere, S. T. Wu, Y. J. Dong. Ultrastable, Highly Luminescent Organic-Inorganic Perovskite - Polymer Composite Films, Advanced Materials, accepted, (2016). [2] Y. J. Dong, J.M. Caruge, Z. Q. Zhou, C. Hamilton, Z. Popovic, J. Ho, M. Stevenson, G. Liu, V. Bulovic, M. Bawendi, P. T. Kazlas, S. Coe-Sullivan, and J. Steckel Ultra-bright, Highly Efficient, Low Roll-off Inverted Quantum-Dot Light Emitting Devices (QLEDs). SID Symp. Dig. Tech. Pap. 46, 270-273 (2015). [3] J. He, H. Chen, S. T. Wu, and Y. J. Dong, Integrated Sensing Platform Based on Quantum Dot Light Emitting Diodes. SID Symp. Dig. Tech. Pap. 47, 344-346 (2016). [4] H. Chen, J. He, J. S. Chen, S. T. Wu and Y. J. Dong, High Efficacy, High Color Quality Hybrid White OLEDs Incorporating Red Quantum Dots with Narrow Emission Bands. SID Symp. Dig. Tech. Pap. 47, 50-52 (2016).

Internet of Things (IoT) is a booming industry. We investigated several (semi-) professional IoT devices in combination with displays (focus on reflective technologies) and LEDs. First, these displays were compared for reflectance and ambient light performance. Two measurement set-ups with diffuse conditions were used for simulating typical indoor lighting conditions of IoT displays. E-paper displays were evaluated best as they combine a relative high reflectance with large contrast ratio. Reflective monochrome LCDs show a lower reflectance but are widely available. Second we studied IoT microprocessors interfaces to displays. A µP can drive single LEDs and one or two Seg 8 LED digits directly by GPIOs. Other display technologies require display controllers with a parallel or serial interface to the microprocessor as they need dedicated waveforms for driving the pixels. Most suitable are display modules with built-in display RAM as only pixel data have to be transferred which changes. A HDMI output (e.g. Raspberry Pi) results in high cost for the displays, therefore AMLCDs are not suitable for low to medium cost IoT systems. We compared and evaluated furthermore status indicators, icons, text and graphics IoT display systems regarding human machine interface (HMI) characteristics and effectiveness as well as power consumption. We found out that low resolution graphics bistable e-paper displays are the most appropriate display technology for IoT systems as they show as well information after a power failure or power switch off during maintenance or e.g. QR codes for installation. LED indicators are the most cost effective approach which has however very limited HMI capabilities.

Fast liquid crystal optical shutters due to fast switching, vibrationless control and optical properties have found various applications: substitutes for mechanical shutters, 3D active shutter glasses, 3D volumetric displays and more. Switching speed depends not only on properties of liquid crystal, but also on applied electric field intensity. Applied field in the shutters can exceed >10 V/micron which may lead to dielectric breakdown. Therefore, a dielectric thin film is needed between transparent conductive electrodes in order to reduce breakdown probability. In this work we have compared electrical and optical properties of liquid crystal displays with dielectric thin films with thicknesses up to few hundred nanometers coated by flexo printing method and magnetron sputtering. Dielectric breakdown values show flexographic thin films to have higher resistance to dielectric breakdown, although sputtered coatings have better optical properties, such as higher transmission and no coloration.

Integral imaging (II) is a good candidate for augmented reality (AR) display, since it provides various physiological depth cues so that viewers can freely change the accommodation and convergence between the virtual three-dimensional (3D) images and the real-world scene without feeling any visual discomfort. We propose two AR 3D display systems based on the theory of II. In the first AR system, a micro II display unit reconstructs a micro 3D image, and the mciro-3D image is magnified by a convex lens. The lateral and depth distortions of the magnified 3D image are analyzed and resolved by the pitch scaling and depth scaling. The magnified 3D image and real 3D scene are overlapped by using a half-mirror to realize AR 3D display. The second AR system uses a micro-lens array holographic optical element (HOE) as an image combiner. The HOE is a volume holographic grating which functions as a micro-lens array for the Bragg-matched light, and as a transparent glass for Bragg mismatched light. A reference beam can reproduce a virtual 3D image from one side and a reference beam with conjugated phase can reproduce the second 3D image from other side of the micro-lens array HOE, which presents double-sided 3D display feature.

Although accommodation response plays an important role in the human vision system for perception of distance, some three-dimensional (3D) displays offer depth stimuli regardless of the accommodation response. The consequence is that most observers watching 3D displays have complained about visual fatigue. The measurement of the accommodation response is therefore necessary to develop human-friendly 3D displays. However, only few studies about accommodation measurement have been reported. Most of the investigations have been focused on the measurement and analysis of monocular accommodation responses only because the accommodation response works individually in each eye. Moreover, a main eye perceives dominantly the object distance. However, the binocular accommodation response should be examined because both eyes are used to watch the 3D display in natural conditions. The ophthalmic instrument that we developed enabled to measure changes in the accommodation response of the two eyes simultaneously. Two cameras acquired separately the infrared images reflected from each eyes after the reflected beams passed through a cylindrical lens. The changes in the accommodation response could then be estimated from the changes in the astigmatism ratio of the infrared images that were acquired in real time. In this paper, we compared the accommodation responses of main eye between the monocular and the binocular conditions. The two eyes were measured one by one, with only one eye opened, during measurement for monocular condition. Then the two eyes were examined simultaneously for binocular condition. The results showed similar tendencies for main eye accommodation response in both cases.

Holographic Displays (HDs) provide 3D images with all natural depth cues via computer generated holograms (CGHs) implemented on spatial light modulators (SLMs). HDs are coherent light processing systems based on interference and diffraction, thus they generally use laser light. However, laser sources are relatively expensive, available only at some particular wavelengths and difficult to miniaturize. In addition, highly coherent nature of laser light makes some undesired visual effects quite evident, such as speckle noise, interference due to stray light or defects of optical components. On the other hand, LED sources are available in variety of wavelengths, has small die size, and no speckle artifact. However, their finite spatial size introduce some degree of spatial incoherence in an HD system and degrade image resolution, which is the subject of the study in this paper. Our theoretical analysis indicates that the amount of resolution loss depends on the distance between hologram and SLM image planes. For some special configurations, the source size has no effect at all. We also performed experiments with different configurations using lasers and LEDs with different emission areas that vary from 50 μm to 200 μm, and determined Contrast Transfer Function (CTF) curves which agree well with our theoretical model. The results show that it is possible to find configurations where LEDs combined with pinholes almost preserve natural resolution limit of human eye while keeping the loss in light efficiency within tolerable limits.

In this paper we propose an investigation of digital optical phase conjugation (DOPC) method applicability and efficiency for the problem of three-dimensional (3D) holographic imaging. We validate the basic properties of developed DOPC-based method for different cases of imaging objects, from simple two-dimensional (2D) case to 3D figure composed of 2D polygons. We implement the method of adaptive optimization of the wavefront (AOWF) for auxiliary image formation. Since the simplicity and universality of AOWF method, this approach is useful for the fast basic 3D holographic image formation.

A novel method of viewing angle enhancement of a real-time integral imaging system using multi-directional projections and GPU parallel processing is proposed. The proposed system is composed of three processes: information acquisition of real objects, generation of multi-directional elemental image sets, and reconstruction of 3D images by using multidirectional projections scheme. To implement this system, depth and color (RGB) information of each object point are captured by a depth camera; then, a dynamic algorithm and GPU parallel processing are used for generating multidirectional elemental image sets to be illuminated in different directions as well as to maintain a real-time processing seed; and finally, 3D images are reconstructed by using a time-multiplexed multi-directional projection scheme through an appropriate optical setup of a projection-type integral image system. Multi-directional illuminations of elemental image sets enhance the optical ray divergence of reconstructed 3D images according to the directional projection angles. Hence, a real-time integral imaging system with enhanced viewing angle is achieved.

A 3D augmented reality display is proposed that can provide glass-free stereo parallax using a highly transparent projection screen. The proposed display is based on a transparent retro-reflective screen and a pair of laser pico projectors placed close to the viewer’s head. The retro-reflective screen directs incident light towards its source with little scattering so that each of the viewer’s eyes only perceives the content projected by the associated projector. Each projector displays one of the two components (left or right channel) of stereo content. The retro-reflective nature of screen provides high brightness compared to the regular diffused screens. The partially patterned retro-reflective material on clear substrate introduces optical transparency and facilitates the viewer to see the real-world scene on the other side of screen. The working principle and design of the proposed see-through 3D display are presented. A tabletop prototype consisting of an in-house fabricated 60×40cm² see-through retro-reflective screen and a pair of 30 lumen pico-projectors with custom 3D printed housings is demonstrated. Geometric calibration between projectors and optimal viewing conditions (eye box size, eye-to-projector distance) are discussed. The display performance is evaluated by measuring the brightness and crosstalk for each eye. The screen provides high brightness (up to 300 cd/m² per eye) using 30 lumens mobile projectors while maintaining the 75% screen transparency. The crosstalk between left and right views is measured as <10% at the optimum distance of 125-175 cm, which is within acceptable range.

Although much progress was made in light emitting devices, the ability to electrically control their spectral emission remains limited. We will present a novel approach and experimental results for dynamic color control, by electrically modulating the non-radiative Forster resonance energy transfer (FRET) efficiency between donor and acceptor dyes in a solution. FRET efficiency depends on the 6th power of the distance between donor and acceptor dye molecules, and thus, it is sensitive to variations in acceptor's concentration. Controlled acceptor concentrations could be achieved by attracting or repelling ionic dyes from the electrodes using a capacitive deionization (CDI) cell, with high surface area porous electrodes. This approach to dynamic color control may open new directions in 100% fill-factor displays, and can be expanded to energy saving applications such as controlling building’s external wall emissivity. We studied the modulation of a single dye emission using a CDI cell with negatively charged Fluorescein Sodium Salt in aquatic solution. Photoluminescence was measured along few charging-discharging CDI cycles and showed the ability to control extensive optical response through CDI. We experimented with two types of FRET-pair dyes: a) anion-cation, where the acceptor and the donor ions are oppositely charged, and b) zwitterion and ion, where the donor is neutral. We found that electrical control on FRET in aquatic solution is weak, due to hydrophobic attractive interaction between the acceptor and the donor. In order to avoid this effect, we are experimenting FRET control in organic solvents. These results will be presented in the talk.

Graphene has received much interest from optical communities largely owing to its photon-like linear energy band structure called Dirac cone. While majority of the recent research has dealt with plasmon and polariton of the two-dimensional material, a recently reported graphene light emitter could render a new dimension of applications, particularly in high-speed optical communication. Moreover chemical vapor deposition (CVD) growth technique for graphene is available today providing means for scalable high quality graphene. The reported graphene emitter provides broadband light emission from visible to mid-infrared which could be instrumental in multi-color display units and optical communications, however a truly large scale implementation has not previously been achieved. Here we demonstrate a CMOS-compatible 262,144 light-emitting pixels array (10 x 10 mm2) based on suspended CVD graphene nano-electro-mechanical systems (GNEMS). A single photoemission area is 19.6 µm2 and a unit pixel is consisting of 512 photoemission devices (16 x 16) where a multiplexer and a digital to analog converter (DAC) are used to control each pixel. This work clearly demonstrates scalability of multi-channel GNEMS light-emitting array, an atomically thin electro-optical module, and further paves a path for its commercial implementation transparent display or high-speed optical communication.

Even barely acceptable quality holographic 3D video displays require hundreds of mega pixels with a pixel size in the order of a fraction of a micrometer, when conventional flat panel SLM arrangement is used. Smaller pixel sizes are essential to get larger diffraction angles. Common flat display panels, however, have pixel sizes in the order of tens of micrometers, and this results in diffraction angles in the order of one degree. Here in this design, an array of commonly available (similar to high-end mobile phone display panels) flat display panels, is used. Each flat panel, as an element of the array, directs its outgoing low-diffraction angle light beam to corresponding small portion of a large size paraboloid mirror; the mirror then reflects the slowly-expanding, information carrying beam to direct it at a certain exit angle; this beam constitutes a portion of the final real ghost-like 3D holographic image. The collection of those components from all such flat display panels cover the entire 360-degrees and thus constitute the final real 3D table-top holographic display with a 360-degrees viewing angle. The size of the resultant display is smaller compared to the physical size of the paraboloid mirror, or the overall size of the display panel array; however, an acceptable size table top display can be easily constructed for living-room viewing. A matching camera can also be designed by reversing the optical paths and by replacing the flat display panels by flat wavefront capture devices.

Conventional methods of compensating for self-distortion in liquid-crystal-on-silicon spatial light modulators (LCOS-SLM) are based on aberration correction, where the wavefront of the incident beam is modulated to compensate for aberrations caused by the imperfect optical flatness of the LCOS-SLM surface. Previously, we proposed an effective method to compensate for the distortion by displaying a compensation phase pattern obtained from interferometry However, the phase distribution of an LCOS-SLM varies with changes in ambient temperature and requires additional correction. The ambient temperature of LCOS-SLMs can vary under certain circumstances, i.e. equipped inside systems for field use or long-term operations. In this presentation, we discussed a novel phase compensation method under temperature-varying conditions based on an orthonormal Legendre series expansion of the phase distribution from viewpoint of multiple beam holographic generation. We found several Legendre coefficients that follow quadratic functions of ambient temperature. This prompted us to propose an algorithm for correcting the temperature dependency by displaying a phase pattern using two simple steps: an initializing step and a temperature correction step. We investigated the temperature dependency by controlling the ambient temperature with an incubator and successfully corrected for self-distortion in a temperature range of approximately 68°F to 122°F, giving an optical flatness of <λ /10. Our approach has the potential to be adopted in tight-focusing applications which require wavefront modulation with very high accuracy. Additionally, the concept of this method is extensible to the thermal behavior of other optical devices, such as lenses and mirrors, which have the possibility of causing unexpected aberrations.

We propose a very low loss multiple-light-source red-green-blue (RGB) power combiner by optical waveguide mode coupling technique. The combiner consists of a two-step circuit that performs both power coupling and wavelength multiplexing for an RBG multiple-light source. The first step of the circuit combines first R, G, and B as the 0th-order mode. The second step combines second R and G by mode conversion from the 0th-order mode to second-order modes using waveguide mode couplers. We used an even mode configuration to avoid asymmetric deformation of the beam due to interference between the modes. By using all of these coupler functions in the two steps, the circuit provides multiplelight-source (RRGGB) power combining. The combiner was fabricated by silica planar lightwave circuit (PLC) technology. The coupler length is about 4.5 mm, including 2.3 mm for the 0th-order coupler and 2 mm for the secondorder coupler. We estimated the coupling loss of both the 0th-order RGB coupler and second-order RG power coupler to be about 1 dB by evaluating the combined power for the 0th-order RGB couplers and the complementary output powers for mode couplers. To the best of our knowledge, this is the first demonstration of a multiple-light-source RRGGB power combiner using multimode coupling. This method enables us to combine a much larger number of light sources using multi-stage coupling for different modes as well. Moreover, the beam shape can be controlled by mode selection.

Advanced imaging and display techniques are widely explored for realistic content capture and visualization but cannot fully follow the miniaturization and mobility trends in technology. Wide field-of-view displays require large surfaces and image capture requires separate installation of cameras having separate footprints and perspective views. Here we propose a novel, portable dual purpose passive screen that can simultaneously facilitate display and imaging with unprecedented features and performance. The optical design of the screen is presented. A prototype of the dual-purpose screen paired with a camera and a low power mobile projector is demonstrated. The developed screen has size of 28×21cm² to facilitate capture of eye contacted perspective view and displays high-quality images with high-brightness (>100cd/m² ) using only 15 lumen pico projector.

Security is one of the big issues in automated teller machine (ATM). In ATM, two types of security have to be maintained. One is to secure displayed information. The other is to secure screen contamination. This paper gives a solution for these two security issues. In order to secure information against peeping at the screen, we utilize visual cryptography for displayed information and limit the viewing zone. Furthermore, an aerial information screen with aerial imaging by retro-reflection, named AIRR enables users to avoid direct touch on the information screen. The purpose of this paper is to propose an aerial secure display technique that ensures security of displayed information as well as security against contamination problem on screen touch. We have developed a polarization-processing display that is composed of a backlight, a polarizer, a background LCD panel, a gap, a half-wave retarder, and a foreground LCD panel. Polarization angle is rotated with the LCD panels. We have constructed a polarization encryption code set. Size of displayed images are designed to limit the viewing position. Furthermore, this polarization-processing display has been introduced into our aerial imaging optics, which employs a reflective polarizer and a retro-reflector covered with a quarter-wave retarder. Polarization-modulated light forms the real image over the reflective polarizer. We have successfully formed aerial information screen that shows the secret image with a limited viewing position. This is the first realization of aerial secure display by use of polarization-processing display with retarder-film and retro-reflector.

Aerial display can form transparent floating screen in the mid-air and expected to provide aerial floating signage. We have proposed aerial imaging by retro-reflection (AIRR) to form a large aerial LED screen. However, luminance of aerial image is not sufficiently high so as to be used for signage under broad daylight. The purpose of this paper is to propose a novel aerial display scheme that features hybrid display of two different types of images. Under daylight, signs made of cubes are visible. At night, or under dark lighting situation, aerial LED signs become visible. Our proposed hybrid display is composed of an LED sign, a beam splitter, retro-reflectors, and transparent acrylic cubes. Aerial LED sign is formed with AIRR. Furthermore, we place transparent acrylic cubes on the beam splitter. Light from the LED sign enters transparent acrylic cubes, reflects twice in the transparent acrylic cubes, exit and converge to planesymmetrical position with light source regarding the cube array. Thus, transparent acrylic cubes also form the real image of the source LED sign. Now, we form a sign with the transparent acrylic cubes so that this cube-based sign is apparent under daylight. We have developed a proto-type display by use of 1-cm transparent cubes and retro-reflective sheeting and successfully confirmed aerial image forming with AIRR and transparent cubes as well as cube-based sign under daylight.

The 3D surface reconstruction is done by analyzing the deformation of the image of binary grating projected onto the relief of an object, after that, the phase of the deformed pattern is extracted by Fourier transform and unwrapping the phase. There are several techniques for image grating projection and one of them is the so called Talbot Effect that creates self-images of a binary gratings. In this work one of the self-image of a grating is used for projection on the relief of an object. The deformed image is captured by a camera and is analyzed by the proposed Extended Fourier Transform (XFT) algorithm. The XFT algorithm is and enhancement of the common FFT algorithm and allows an improvement in surface reconstruction. A comparison between the reconstructed surfaces using traditional FFT algorithm and the proposed XFT algorithm is presented.

Due to the worldwide portable devices and illumination technology trends, researches interest in laser diodes applications are booming in recent years. One of the popular and potential LDs applications is near-eye display used in VR/AR. An ideal near-eye display needs to provide high resolution, wide FOV imagery with compact magnifying optics, and long battery life for prolonged use. However, previous studies still cannot reach high light utilization efficiency in illumination and imaging optical systems which should be raised as possible to increase wear comfort. To meet these needs, a waveguide illumination system of near-eye display is presented in this paper. We focused on proposing a high efficiency RGB LDs light engine which could reduce power consumption and increase flexibility of mechanism design by using freeform TIR reflectors instead of beam splitters. By these structures, the total system efficiency of near-eye display is successfully increased, and the improved results in efficiency and fabrication tolerance of near-eye displays are shown in this paper.

This PDF file contains the front matter associated with SPIE Proceedings Volume 10126, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.