Design and fabrication of Bragg gratings for transparent smart surfaces
Abstract: A concave mirror is designed and recorded as reflective Bragg gratings on transparent photopolymer layers, which can be laminated on glass surfaces to generate color images without ghost effect for compact augmented reality laser displays.
© 2018 OSJ Keywords: Bragg grating, volume hologram, laser projector, augmented reality, transparent display, ghost image
1. Introduction Transparent surfaces have been used as the combiner in numerous display applications for Augmented Reality (AR), e.g. smart glasses and Head-Up Display (HUD) [1]. One issue is the reflections from multiple surfaces of the glasses, leading to the ghost effect, as illustrated in Fig. 1, while another issue is the package size of the optical system required to magnify the image to provide a necessary Field of View (FoV). There is also a need to generate farther, multiple or variable virtual image planes for AR, leading to an even higher optical system package size.
Different approaches have been proposed to remove the ghost image, as well as to reduce the optical system package size. A wedge combiner can be fabricated to bring the reflections from the two surfaces closer together, at the constraints of manufacturing cost and precision, especially on a wide display area as in a windshield HUD [2]. A holographic waveguide system on a flat glass with multiple total internal reflections can be used to reduce the optical path inside the optical system, but there is still a need to magnify the image to provide the required FOV. In this paper, we report the use of a reflective Bragg grating which is designed and recorded as a concave mirror to remove the ghost effect and to reduce the package size.
4. Experimental results To evaluate the display system experimentally, we recorded the optical function of a spherical mirror into two holograms using Bayfol® HX200 photopolymers at red and green laser wavelengths. The recorded films were then laminated on flat glass surfaces using Liquid Optically Clear Adhesive and spatially aligned to match the reflections from the two colors. A laser scanning projector from MicroVision [5] was used to generate a real, full color image on a light shaping diffuser, which illuminates the combined reflection hologram structure at perpendicular direction.
Fig. 5 shows the image observed at about 30° from the combined reflection holograms, consisting of two color red and green. The image reflection from the glass surfaces, i.e. the ghost image, can be observed only at perpendicular direction of the structure, hence separated from the two color virtual image. Moreover, this image is bigger and farther away from the structure surface than the ghost image, without the need of magnification optics, thanks to the optical power recorded in the holograms. The background information is also clearly visible through the combined reflection hologram surfaces, allowing AR content to be shown.
5. Conclusions: In summary, we have designed and recorded reflective holograms with spherical wavefront on transparent photopolymer layers, to generate two color images without ghost effect for compact augmented reality laser displays. Future work will focus on the recording of more complex optical function, for full color image and on a single photopolymer layer for easier alignment of the color channels.
6. References [1] N. Kim, Y. L. Piao and H. Y. Wu, “Holographic Optical Elements and Application”, IntechOpen, 2017. [2] B. Kress and P. Meyrueis, “Applied Digital Optics: From Micro-optics to Nanophotonics”, John Wiley & Sons, 2009. [3] M. U. Erdenebat, Y. T. Lim, K. C. Kwon, N. Darkhanbaatar and N. Kim, “Waveguide-Type HeadMounted Display System for AR Application”, IntechOpen, 2018. [4] LightTrans GmbH, www.lighttrans.com. [5] MicroVision Inc, www.microvision.com.
h/t Joe_spaz, Sweetinnj: Reddit thread
Figure 5: A two color virtual image from the
combined reflection hologram structure
Abstract: A concave mirror is designed and recorded as reflective Bragg gratings on transparent photopolymer layers, which can be laminated on glass surfaces to generate color images without ghost effect for compact augmented reality laser displays.
© 2018 OSJ Keywords: Bragg grating, volume hologram, laser projector, augmented reality, transparent display, ghost image
1. Introduction Transparent surfaces have been used as the combiner in numerous display applications for Augmented Reality (AR), e.g. smart glasses and Head-Up Display (HUD) [1]. One issue is the reflections from multiple surfaces of the glasses, leading to the ghost effect, as illustrated in Fig. 1, while another issue is the package size of the optical system required to magnify the image to provide a necessary Field of View (FoV). There is also a need to generate farther, multiple or variable virtual image planes for AR, leading to an even higher optical system package size.
Different approaches have been proposed to remove the ghost image, as well as to reduce the optical system package size. A wedge combiner can be fabricated to bring the reflections from the two surfaces closer together, at the constraints of manufacturing cost and precision, especially on a wide display area as in a windshield HUD [2]. A holographic waveguide system on a flat glass with multiple total internal reflections can be used to reduce the optical path inside the optical system, but there is still a need to magnify the image to provide the required FOV. In this paper, we report the use of a reflective Bragg grating which is designed and recorded as a concave mirror to remove the ghost effect and to reduce the package size.
4. Experimental results To evaluate the display system experimentally, we recorded the optical function of a spherical mirror into two holograms using Bayfol® HX200 photopolymers at red and green laser wavelengths. The recorded films were then laminated on flat glass surfaces using Liquid Optically Clear Adhesive and spatially aligned to match the reflections from the two colors. A laser scanning projector from MicroVision [5] was used to generate a real, full color image on a light shaping diffuser, which illuminates the combined reflection hologram structure at perpendicular direction.
Fig. 5 shows the image observed at about 30° from the combined reflection holograms, consisting of two color red and green. The image reflection from the glass surfaces, i.e. the ghost image, can be observed only at perpendicular direction of the structure, hence separated from the two color virtual image. Moreover, this image is bigger and farther away from the structure surface than the ghost image, without the need of magnification optics, thanks to the optical power recorded in the holograms. The background information is also clearly visible through the combined reflection hologram surfaces, allowing AR content to be shown.
5. Conclusions: In summary, we have designed and recorded reflective holograms with spherical wavefront on transparent photopolymer layers, to generate two color images without ghost effect for compact augmented reality laser displays. Future work will focus on the recording of more complex optical function, for full color image and on a single photopolymer layer for easier alignment of the color channels.
6. References [1] N. Kim, Y. L. Piao and H. Y. Wu, “Holographic Optical Elements and Application”, IntechOpen, 2017. [2] B. Kress and P. Meyrueis, “Applied Digital Optics: From Micro-optics to Nanophotonics”, John Wiley & Sons, 2009. [3] M. U. Erdenebat, Y. T. Lim, K. C. Kwon, N. Darkhanbaatar and N. Kim, “Waveguide-Type HeadMounted Display System for AR Application”, IntechOpen, 2018. [4] LightTrans GmbH, www.lighttrans.com. [5] MicroVision Inc, www.microvision.com.
Edited Transcript of VC earnings conference call or presentation 21-Feb-19 2:00pm GMT
Sachin S. Lawande, Visteon Corporation - President, CEO & Director
The vehicle cockpit is evolving at a rapid pace from a technology perspective as consumers are expecting similar digital capabilities and experiences from cockpit electronics as with their smartphones and tablets. Large displays with rich graphics, over-the-air software update capability and cloud-enabled apps are the new competitive battleground for car manufacturers. This trend is not impacted by the market slowdown as car manufacturers are forced to upgrade the cockpit to compete with rapidly evolving consumer devices.
The more immediate impact of this trend has been the conversion of the cockpit into a multi-display, digital and connected environment. The instrument cluster is evolving from gauges and LEDs to additional display-based system. Infotainment systems, which used to be closed and proprietary, are now connected app platforms even at the entry level. Digital displays in the cockpit are growing, both in number as well as in size, and the form factor is evolving into curved and non-rectangular shapes to fit with the design of the interior of the vehicles. These trends are impacting the industry now, and car manufacturers are looking to suppliers to provide these advanced solutions.
Looking ahead, the emergence of artificial intelligence-based smart assistance, coupled with higher levels of automated driving, will enable the cockpit to effectively become a smart assistant on wheels. Early implementations of AI in the cockpit in China are already launched in the market and are indicative of the future of the cockpit.
Visteon has been evolving a technology portfolio over the past 3 years to address these cockpit electronics trends. Our digital cluster, displays and infotainment solutions are already performing well in the market. In 2018, we made further progress on our technology vision for the company. We introduced the first cockpit domain controller solution in the industry with Daimler. We also introduced an Android-based infotainment system and an autonomous driving controller for Level 2-plus systems. And at the CES show in Las Vegas last month, we introduced 2 AI-based solutions for conversational voice assistant and driver monitoring applications as well as advanced multi-display system with sensor integration.
Our technology portfolio has never been stronger with innovative technology platforms for rapid development of integrated digital cockpit systems. We are confident that our technology portfolio will continue to position Visteon as a leader in cockpit electronics technology [to] help drive new business wins in the future.
h/t Joe_spaz, Sweetinnj: Reddit thread
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