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Near-to-Eye Display Using Scanning Fiber Display Engine
Abstract
: A novel near-to-eye display has been demonstrated, using a scanning fiber as the image source. Light is relayed from remote sources to the scanner via singlemode optical fiber. As a replacement for conventional LCD image sources, the fiber scanner reduces weight and power consumption, and enables a water-immersible display.
... In this regard, piezo-scanning fiber probes have been widely utilized in biological studies such as calcium imaging of the rat cerebellum[5], epithelial imaging[6], monitoring collagen morphology in the cervix[7], minimally invasive imaging of the mouse lung and colon tissues[8], brain imaging in freely moving animals[9]. With their superior form factor, piezo-scanning fiber probes have also been involved in commercial applications, such as compact display systems[10,11]. In a piezo-scanning fiber probe, light is mapped onto the tissue that is exiting the extended optical fiber, which is encircled and actuated by a cylindrical piezoelectric tube. The piezo-tube, which converts applied voltage to mechanical movement, is driven at the mechanical resonance of the extended fiber to create the desired scan pattern. ...
... In this regard, piezo-scanning fiber probes have been widely utilized in biological studies such as calcium imaging of the rat cerebellum [5], epithelial imaging [6], monitoring collagen morphology in the cervix [7], minimally invasive imaging of the mouse lung and colon tissues [8], brain imaging in freely moving animals [9]. With their superior form factor, piezo-scanning fiber probes have also been involved in commercial applications, such as compact display systems [10,11]. In a piezo-scanning fiber probe, light is mapped onto the tissue that is exiting the extended optical fiber, which is encircled and actuated by a cylindrical piezoelectric tube. ...
... With the development of virtual reality (AR) and augmented display (VR) industries in recent years, micro display technology which can be used in portable devices has received a lot of attention. Single-fiber scanning technology was initially used for biological endoscopy imaging [1], but its promise in the field of micro display was soon discovered [2][3][4].Single-fiber scanning projectors use lasers as light sources to produce colorful images with a wide gamut, and RGB full-color displays do not add additional structure compared to monochromatic displays. ...
... However, previous scanning fiber displays utilize multiple optical components that makes the overall device bulky. Furthermore the optical components are placed on the optical axes, making such displays only suitable as virtual reality (VR) devices [9,10]. Here, we demonstrate a fiber-scanning HWD type (small form-factor) microdisplay design and implementation that only incorporates an elliptic or ellipsoidal reflective mirror (or partially reflective for augmented reality applications) surface to map the fiber tip onto the retina. ...
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 ∼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.
... Nevertheless, more optical elements are required for this optimized design, which results in incompact form factors. The design based on fiber scanner also suffers from this kind of tradeoff [9]. In addition, multi-plane VR display have achieved nearly accommodation by employing time-multiplex or multi-planar technique to display the images of 3D scene at discrete corresponding distances [10][11][12][13]. ...
We propose a bifocal computational near eye light field display (bifocal computational display) and structure parameters determination scheme (SPDS) for bifocal computational display that achieves greater depth of field (DOF), high resolution, accommodation and compact form factor. Using a liquid varifocal lens, two single-focal computational light fields are superimposed to reconstruct a virtual object’s light field by time multiplex and avoid the limitation on high refresh rate. By minimizing the deviation between reconstructed light field and original light field, we propose a determination framework to determine the structure parameters of bifocal computational light field display. When applied to different objective to SPDS, it can achieve high average resolution or uniform resolution display over scene depth range. To analyze the advantages and limitation of our proposed method, we have conducted simulations and constructed a simple prototype which comprises a liquid varifocal lens, dual-layer LCDs and a uniform backlight. The results of simulation and experiments with our method show that the proposed system can achieve expected performance well. Owing to the excellent performance of our system, we motivate bifocal computational display and SPDS to contribute to a daily-use and commercial virtual reality display.
... Based on fiber scanning, Schowengerdt. et al. has proposed a near-eye light field display design by using a fast scanning fiber to display multi-view scene [3]. The amount of information is limited by the characteristics of the fiber, which results in a tradeoff between refresh rate and resolution. ...
We introduce a near eye light field display proposal to reconstruct a light field in high synthesis speed by utilizing the multi-layer light field display technology and human visual features. The resolution distribution of the reconstructed light field is set to be identical to human visual acuity which decreases with the increasing visual eccentricity. We compress the light field information by using different sampling rates in different visual eccentricity area. A new optimization method for the compressed light field is proposed, which dramatically reduces the amount of calculation. The results demonstrate that the acceleration of the proposed scheme is obvious and escalates when the spatial resolution increases. The synthesis scheme is verified and its key aspects are analyzed by simulation and an experimental prototype.
... Micro scanning mirrors are more prevalent in volume of research, but have complex designs and constrain packaging due to the fact that the mirrors need to be larger than the light source beam width 7 . Actuated single scanning waveguides offer a simpler solution 4 , and have been demonstrated to be effective in endoscopic devices and wearable displays [8][9] . For these reasons, the scanning waveguide concept is being used with the exploration of new actuator designs at the University of Washington [10][11] . ...
A new lead-zirconium-titanate (PZT) actuator design for a micro scanning illuminating device is being developed. The thin PZT film is deposited directly on stainless steel by using an aerosol deposition machine. The aerosol deposition method enables inexpensive, quick, room temperature fabrication while producing high quality PZT films. The presented scanners would be attractive for endoscopic device applications, where inexpensive systems with high resolution would be a move toward disposal endoscopes. The design of this scanning illuminator and fabrication method are presented. Measurements of the PZT layer surface roughness and the aerosol deposited PZT powder particle diameter are presented. Ongoing work and fabrication challenges are discussed.
... At this actuator resonance rate, a single projector can scan 2000 pixels per each of the 250 rings per refresh cycle, at an overall refresh rate of 30 Hz. The miniature size of these projectors allowed Schowengerdt et al.[65]to integrate them into a relativelycompact RSD HMD prototype. Schowengerdt et al.[33]then produced a bevelled array of these scanned fiber projectors, where each head is offset from the previous to project to its own focal depth. ...
For ultra-compact near-eye display, waveguides provide a small form factor because they are thin shape plate, but projectors are too large due to the imaging sources, which results in bulky near-eye displays. Recent advances in fiber-scanning technology can overcome this limitation. Fiber-scasnning projectors produce an image by vibrating an optical fiber, and they can be small because only thin fibers and actuators are required. However, uneven brightness occurs when augmented reality images from the fiber-scanning projector are displayed using a conventional waveguide. In this paper, we propose a novel waveguide that duplicates a narrow beam by multiple reflections of a pre duplicator, which is a flat-plate-shaped optics with mirror and half-mirror surfaces. The proposed waveguide enables uniform luminance distribution with a fiber-scanning projector by providing narrow duplication intervals. We experimentally confirmed that the contrast of luminance unevenness decreased from 0.60 to 0.15 with our waveguide. Our fiber scanning projector size is less than 0.03 cc and can be placed on the temples of eyeglasses, which is impossible with general projectors of about 5 cc. Therefore, the proposed waveguide and fiber scanning projector enable the realization of eyeglasses shape near-eye displays.
We are developing a projection unit in a three‐step process involving our previously proposed fiber‐scanning methods (first two steps, which have been completed) and another fiber‐scanning method, called cross‐limit (X‐Limit), we propose for this paper that provides high resolution, uniform brightness, and a rectangular display area, which are difficult with previous methods. The development of X‐Limit is the third and final step in developing this projection unit.
We are developing a projector system with scanning fiber device and its control system. Our novel scanning systems of scanning fiber device provide high resolution, uniform brightness, and rectangular display area, which are difficult challenges in conventional scanning fiber device. Scanning fiber device is suitable for embedding into small display such as head‐mounted display due to its small size. In this study, we developed a novel scanning control system of scanning fiber device, which can improve the image quality. We confirmed that the bright spots are moved to the outside of the drawing area, and the drawing area shape is closer to a rectangle, by experiment with novel scanning control. Further, it is possible to increase the resolution with higher laser modulation frequency.
We propose a deep depth of field near eye light field displays utilizing LC lens and dual‐layer LCDs utilizing LC lens and dual‐layer LCDs. Furthermore, a structure parameters optimization scheme is proposed to determine the parameters of form factors. A prototype was constructed to verify our proposal. This proposal achieves high resolution, simple form factor and improved depth of field, which overcomes the convergence‐accommodation conflict effectively.
A novel pan-tilt user-interface (UI) robot system uses a scanning MEMS projection head in combination with a depth sensor. The UI robot system can detect and track a hand, then project a virtual-remote-controller (VRC) image onto the top of a palm or table.
We present a novel pan-tilt projection UI robot system using a laser light source with a MEMS scanner in combination with a hand tracking sensor. The UI robot system can detect and track a hand and then project a virtual remote controller (VRC) image onto the top of a palm.
A new lead-zirconium-titan ate (PZT) actuated scanning light source design is proposed. An Aerosol deposition process will be used to construct a high quality 5 μm thick film of PZT. The PZT actuator will induce non-linear vibrations to scan an area with a cantilever waveguide. The fabrication procedure for the design is presented. Fabrication results are discussed. A finite element analysis of the actuator pad is also presented. Fabrication steps needed for a comparison of the amplitude of actuation, resolution, and frequency of scan with previously developed Si based devices are also discussed.
We propose a novel fiber pigtailed integrated laser module for pico‐projector and near‐to‐eye display applications using Si‐platform technology based on surface activation bonding. The module consists of synthetic blue (B) and green (G) second harmonic generation (SHG) lasers and a direct red (R) laser diode (LD). We also present its basic performance and discuss its further integration capabilities.
We present a novel multiple laser beam scanning projection module using compact red-green-blue (RGB) fiber pigtailed laser modules for use in a high resolution pico-projector display system using a fiber bundle combiner in combination with a single MEMS mirror. This system can be used to create accurate multiple-projection images on a screen without overlaps or spaces among the projection images. The system uses very simple projection optics and has the potential to become a light engine unit for use in multiple projection systems, particularly those for light field displays. As such, light field display applications are also discussed.
We report progress in developing high-contrast, wide symmetrical viewing angle multi-domain vertical alignment (MVA) AMLCD's with a full color SXGA resolution (1280x1024x3 dots). These MVA displays are fabricated with a smooth surface and without either protrusions or an ITO slit-pattern geometry. Intrinsic fringe fields in each pixel control the LC alignment and formation of domains. We have achieved contrast ratios greater than 1000, and symmetrical viewing angles greater than 120 degrees. A 3840x1024 dot array was developed with integrated color pixel filters to create a 1280x1024 color pixel array. The pixel design, display driver operation, and color mosaic were optimized for MVA operation. Pixel shapes were developed to control domain formation and to maximize light transmission using 3-D modeling and test displays. New LC materials were investigated to increase transmission and to minimize voltage drive requirements. Improvements have been made in this MVA liquid crystal display to bring the fabrication process closer to manufacturing. Key results include striation-free displays with spun-on polyimide alignment layers, elimination of boundary stick via pixel design, overall viewing angle improvement with an MVA-matched wide viewing polarizer, and transmission improvements with high delta n LC, cell gap, driving mode, LED and BEF backlight combination. Performance data and specifications for Kopin's color filter MVA and TN displays will be presented with reference to military, industrial, and commercial applications.
We report design and test of a high brightness laboratory-breadboard LED/LCOS HMD system employing a 0.78- inch-diagonal 1280 x 768 ferroelectric liquid-crystal-on-silicon microdisplay and a red-green-blue LED. With an 8x viewing optic giving a 35 degree diagonal field of view, the system yielded brightnesses greater 40,000 cd/m2 (12,000 fL) in color-sequential mode and greater than 100,000 cd/m2 (30,000 fL) in monochrome mode, at LED power consumptions of 1.1 W and 3.3 W, respectively. The illumination optics employed a rectangular light pipe and tailored diffuser to efficiently fill the microdisplay panel aperture and exit pupil. The high efficiency of such image generators facilities display readability in see-through HMDs operating in high-ambient-light environments, as well as enabling ultra-low power HMDs (less than 100 mW total) for dismounted users of battery-powered systems.
Lasing in pure green region around 520 nm of InGaN based laser diodes (LDs) on semi-polar 2021 free-standing GaN substrates was demonstrated under pulsed operation at room temperature. The longest lasing wavelength reached to 531 nm and typical threshold current density was 8.2 kA/cm2 for 520 nm LDs. Utilization of a novel 2021 plane enabled a fabrication of homogeneous InGaN quantum wells (QWs) even at high In composition, which is exhibited with narrower spectral widths of spontaneous emission from LDs than those on other planes. The high quality InGaN QWs on the 2021 plane advanced the realization of the green LDs. ©2009 The Japan Society of Applied Physics
For a lot of HMD application it is desirable to know where the user is looking at. For this purpose an ocular OLED-HMD system with collinear eye-tracking was developed. A viewing angle of 36° is realized in combination with an eye-tracker FOV of 20mm. The system is desired for medical applications.
Media playback capabilities of mobile devices demand a large display in a small package. We have developed a 1-mm x 9-mm scan engine, projecting full-color images through a vibrating optical fiber tip and miniature lens system. Connected by optical fiber, the projection head and RGB light sources can be distributed across the mobile device.
Advances in mobile devices have enabled internet access and viewing of images and video, but small screens constrain the experience. We have developed a novel scanning fiber optical projector that is 1.07 mm in diameter and 13 mm long, and can project images at up to a 100° throw angle.
Mobile pico projectors need to project on surfaces at a variety of distances, for which different throw angles produce optimal image size and brightness. By electronically adjusting the peak drive voltage to our 1-mm x 9-mm scanning fiber engine, we demonstrate rapid (resolution-maintaining) rescaling of throw angles up to 100°.
Optical fibers are microfabricated and piezoelectrically vibrated to produce rectilinear scan patterns. By coupling a laser to the optical fiber and projecting the collimated light directly to the viewer's eye, the result is a proposed low-cost, spectacle-mounted, wearable low vision aid.
Conventional stereoscopic displays require viewers to unnaturally keep eye accommo- dation fixed at one focal distance while they dynamically change vergence to view objects at different distances. This forced decoupling of reflexively linked processes fatigues eyes, causes discomfort, compromises image quality, and may lead to pathologies in developing visual systems. Volumetric displays can overcome this conflict, but only for small objects placed within a limited range of viewing distances and accommodation levels, and cannot render occlusion cues correctly. Our multi-planar True 3-D displays generate accommodation cues that match vergence and stereoscopic retinal dispar- ity demands and can display images and objects at viewing distances throughout the full range of human accommodation (from 6.25 cm to infinity), better mimicking natural vision and minimizing eye fatigue.
The Wearable Low Vision Aid (WLVA) is a portable system that uses machine vision to track potential walking hazards for the visually impaired. A scanning fiber display couples a laser diode to a vibrating optical fiber that projects a virtual image onto the retina to display warning icons that the visually impaired can recognize. Initial low-vision subject testing has given promising results for this low-cost assistive device.
Recent research suggests that entering an immersive virtual environment can serve as a powerful nonpharmacologic analgesic for severe burn pain. The present case study describes an attempt to use water-friendly virtual reality (VR) technology with a burn patient undergoing wound care in a hydrotherapy tub. The patient was a 40-year-old male with 19% total body surface area deep flame/flash burns to his legs, neck, back, and buttocks. The virtual reality treatment decreased the patient's sensory and affective pain ratings and decreased the amount of time spent thinking about his pain during wound care. We believe that VR analgesia works by drawing attention away from the wound care, leaving less attention available to process incoming pain signals. The water-friendly VR helmet dramatically increases the number of patients with severe burns that could potentially be treated with VR (see http://www.vrpain.com).