Research Project: Wearable Augmented Reality 3D Displays
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Contributors
Funders
ID
EC.00062
Authors
Ürey, Hakan
Faculty Member
Publications
Light-efficient augmented reality 3D display using highly transparent retro-reflective screen
(Optical Society of America (OSA), 2017) Soomro, Shoaib Rehman; Ürey, Hakan; Department of Electrical and Electronics Engineering; Yes; College of Engineering
We propose and demonstrate a light efficient 3D display using a highly transparent desktop-size augmented reality screen. The display consists of a specially designed transparent retro-reflective screen and a pair of low power pico-projectors positioned close to the viewer’s eyes to provide stereo views. The transfer screen is an optically clear sheet partially patterned with retro-reflective microspheres for high optical gain. The retro-reflective material buried in the screen reflect incident light back towards the projectors with narrow scattering angle and facilitates the viewer to perceive a very bright content. The tabletop prototype mainly consists of an in-house fabricated large AR screen (60x40cm2) and a pair of laser scanning 30 lumen pico-projectors. The display is tested for different viewing configurations, different display parameters such as retro-reflective coefficient, eye-box size, polarization maintainability, stereo crosstalk and brightness. The AR prototype display provides 75% optical transparency, exceptional brightness (up to 1000 cd/m2 when viewed through beam-splitters and 350 cd/m2 with bare eyes) and negligible crosstalk in 3D mode (<5% and <1% when viewed through beam-splitters and polarizers respectively) for the working distance of up to 2 meters.
Micro-mirror-array based off-axis flat lens for near-eye displays
(Optical Society of America (OSA), 2019) Kazempourradi, Seyedmahdi; Ulusoy, Erdem; Ürey, Hakan; Yaras, Yusuf Samet; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
We developed an off-axis diffractive lens using a micro-mirror array on a flat substrate. MMA creates an on-axis converging beam from a 45 degrees off-axis diverging illumination beam and functions similar to a large and bulky elliptical mirror. The array consists of individual micro-mirrors with normal directions that vary across the component. The size, normal direction and the center height of each micro-mirror are optimized to achieve a phase matching condition so that the smallest focal spot size is achieved at the design wavelength. Design can also be optimized for full color applications using a synthetic design wavelength. A sample MMA of size 3 mm by 5 mm is fabricated using grayscale lithography. The designed MMA is used to illuminate a computer-generated hologram in a near-eye display system. Experimental results verify the premises of the designed component.
Augmented reality 3d display using head-mounted projectors and transparent retro-reflective screen
(Society of Photo-optical Instrumentation Engineers (SPIE), 2017) Soomro, Shoaib Rehman; Ürey, Hakan; Department of Electrical and Electronics Engineering; Yes; College of Engineering
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 60x40cm(2) 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.
Scanning fiber microdisplay: design, implementation, and comparison to MEMS mirror-based scanning displays
(Optical Society of America (OSA), 2018) Çivitçi, Fehmi; Khayatzadeh, Ramin; Ürey, Hakan; Ferhanoğu, Onur; Department of Electrical and Electronics Engineering; Yes; College of Engineering
In this study, we propose a compact, lightweight scanning fiber microdisplay towards virtual and augmented reality applications. Our design that is tailored as a head-worn-display simply consists of a four-quadrant piezoelectric tube actuator through which a fiber optics cable is extended and actuated, and a reflective (or semi-reflective) ellipsoidal surface that relays the moving tip of the fiber onto the viewer's retina. The proposed display, offers significant advantages in terms of architectural simplicity, form-factor, fabrication complexity and cost over other fiber scanner and MEMS mirror counterparts towards practical realization. We demonstrate the display of various patterns with similar to VGA resolution and further provide analytical formulas for mechanical and optical constraints to compare the performance of the proposed scanning fiber microdisplay with that of MEMS mirror-based microdisplays. Also we discuss the road steps towards improving the performance of the proposed scanning fiber microdisplay to high-definition video formats (such as HD1440), which is beyond what has been achieved by MEMS mirror based laser scanning displays.
Fast computer-generated hologram computation using rendered depth map image
(Society of Photo-optical Instrumentation Engineers (SPIE), 2017) Kazempourradi, Seyedmahdi; Ulusoy, Erdem; Ürey, Hakan; Bjelkhagen, Hans I.; Bove, V. Michael; Department of Electrical and Electronics Engineering; Yes; College of Engineering
We propose a method for computing realistic computer-generated holograms (CGHs) of three-dimensional (3D) objects, where we benefit from well-established graphical processing units (GPUs) and computer graphics techniques to handle occlusion, shading and parallax effects. The graphics render provides a 2D perspective image including occlusion and shading effects. We also extract the depth map data of the scene. The intensity values and 3D positions of object points are extracted by combining the rendered intensity image and the depth map (Z-buffer) image. We divide the depth range into several planes and quantize the depth value of 3D image points to the nearest plane. In the CGH computation part, we perform proper Fresnel transformations of these planar objects and sum them up to create the hologram corresponding to the particular viewpoint. We then repeat the entire procedure for all possible viewpoints and cover the hologram area. The experimental results show that the technique is capable of performing high quality reconstructions in a fast manner.
