Small is beautiful. Small and brightly coloured is very beautiful indeed! Belgium companies QustomDot BV and chip designers MICLEDI Microdisplays BV have teamed up to produce a major advance in mass producing display devices for augmented and virtual reality (AR and VR) applications.
MicroLED displays are emerging as possibly the best devices for AR and VR applications in the metaverse. They are bright, high resolution and have low power consumption. Gallium nitride microLED sources are small and bright but typically emit blue light. Great for a blue display but what about red and green pixels? This is where the QustomDot technology comes in. QustomDot have developed quantum dot materials which absorb blue light and re-emit green or red light.
So why are these quantum dots special? Cadmium sulphide (CdS) or selenide materials have been around for some time but cadmium is problematic in the environment and avoided in new materials technologies. QustomDot have a solution (literally). Their indium phosphide (InP) dots have high efficiency and avoid the use of harmful cadmium. By controlling the size of the nano-particles, they are able to change the colour of light the quantum dots emit. InP based dots can be produced not only in solutions but also transferred to surfaces such as those of gallium nitride microLEDs.
Partners MICLEDI, a spin-out from the Belgian microelectronics hub at IMEC, are able to produce the required wafer-scale GaN microLEDs. The significance of the technology is that IMEC has decades of experience of advanced CMOS fabrication. CMOS technology can produce industry standard 12″ wafers with sub-micro resolution and alignment of transfers. Amazing.
Competing technologies based on less well-established materials currently produce 4″ wafers, with more development work required to scale-up. It remains to be seen which technology will finally win in the AR/VR marketplace.
What happens when you put two superior optical technologies together? In the case of smart glasses you get bigger, brighter and less blurry.
Kingsman-style smart glasses have been available for more than a year now but they typically have flat glass lenses which are difficult to adjust for the 50% of the adult population who wear prescription glasses. A new joint venture between microLED device manufacturer Jade Bird Display (JBD) and smart glasses developer tooz technologies GmbH (tooz) is set to change that. On January 20th 2022 the companies announced a collaboration to put bright microLED displays into glasses with curved lenses. A first demonstration is taking place at the Photonics West SPIE AR VR MR 2022 exhibition (23rd – 25th January 2022 in San Francisco, USA).
Almost exactly one year ago Corbeau reported an Insight on new micro-LED driven smart glasses from Vuzix, a major breakthrough in terms of connectivity and what we now call the Metaverse. With existing products for industrial and medical applications, Vuzix announced the NGSG (Next Generation Smart Glasses) for the consumer market. NGSG combined tiny high resolution microLED red/green/blue displays with their state-of-the-art waveguide optics for displaying 3D images in front of the wearer’s eyes.
In the past year a number of new players have entered the market with their own smart glasses. Xiaomi, a budget smartphone manufacturer from China, has glasses with a monochrome green display based on what looks like a Jade Bird Display 0.1″ device. Lenovo has launched the ThinkReality A3 with high resolution AR display but a rather heavy look. TCL’s Nxtwear G glasses offer high resolution cinema-style projection and get around the prescription lenses issue with a custom frame that looks a bit like Neo and Trinity’s eyeware from the Matrix. But on stalks.
tooz (it seems strange to start a sentence without a capital letter) make much of their new curved waveguide technology. Vuzix developed a waveguide element to their smart glasses which enabled light of different wavelengths to be projected as a image in three dimensions in front of the wearer’s eyes. This was amazingly cool. tooz have gone one better and invented a curved waveguide, which realises a number of improvements to the design and performance of smart glasses. Reading through technical presentations from tooz, Corbeau spotted seven major advantages of curved waveguides compared to planar waveguides:
unbreakable plastic rather than brittle glass
lighter and more compact than glass
use less optical elements due to curved surfaces bending light
require just one waveguide layer rather than one for each colour
material rejects sunlight and rain interference outdoors
curved waveguide reduces display visibility to others
curved waveguide claimed to be more efficient than planar ones
Where do Jade Bird Display fit into the picture? tooz started developing their smart glasses with OLED light sources rather than microLED. OLEDs typically have some advantages but their big disadvantage is the displays are not as bright as microLED displays. Waveguides have amazing properties but are lossy, they waste much of the light intensity passing through them. The tiny microLED displays from JBD have brightness values of millions of nits (the iPad has a humble several thousand nits). This means they can be used outdoors in full sun, to project usable images over wide angles even though much of the light is lost in the waveguide. JBD also have a rather neat X-cube optic which combines the outputs from tiny individual red, green and blue microLED displays no bigger than a grain of rice.
So where does this great technical synergy lead? With the possibility of smart glasses for the whole population, including the 50% who require prescription lenses, a massive potential market is opened up. tooz aren’t just targeting technophiles, they have real-life commercial applications in their sights. Vuzix have a business model that has targetted early adopters in the engineering services sector. tooz are pushing their new products into engineering and medicine. They have a fascinating promo video of a pilot study at the University Hospital of Dresden (see the bottom of this Insight for a link).
One more thing. tooz started out as a new venture between optics experts Carl Zeiss and IT giant Deutsche Telekom. They have automated manufacture for volume manufacture of optics and real reach into IoT in the field.
Smart glasses are now real products with commercial benefits. The party is just getting started and we haven’t seen what Apple and Facebook will bring to the party yet. Could the next two years see the death of the smart phone and the birth of the Matrix?
Autumn is a time of year that the folk at Porotech in Cambridge, UK seem to love. Those deep red autumn colours mark a year of significant growth. This time last year Porotech announced they could fabricate wafer-scale red emitting nano-porous InGaN, suitable for microLEDs.
This autumn Porotech are announcing a ‘world first’ red microLED display based on InGaN. Red microLED display devices based on InGaN are a game-changer for AR (augmented reality) and VR (virtual reality) display devices. Why?
All video display devices are based on composite red, green and blue light signals which the human eye recognises as a millions of different colours. To achieve this pc monitors, televisions and digital projectors use red, green and blue light sources. A variety of different LED choices are available for each of these colours however until recently their light emitting materials had quite different compositions. For large panel displays this is not a huge problem, individual LEDs can be picked and placed together by machine. Tiny display devices used in AR are much more demanding.
For smart glasses, the display device must be less than 10 mm in size and to get anything approaching high definition, it must contain something like 1000×1000 pixels. A simple sum tells us that each of the one million pixels can be no larger than 10 microns! Modern microelectronics fabrication methods can easily make structures 100 times smaller than this but mixing different LED materials is a huge practical challenge. Enter the Porotech solution.
Porotech was spun out of the University of Cambridge to exploit so-called nano-porous gallium nitride materials. InGaN (indium gallium nitride) is a compound semiconductor whose optoelectronic properties can be tuned not only by changing the precise composition but also by creating nano-scale voids.
The traditional way to produce red light from InGaN was to add aluminium and phosphorous atoms to produce red-emitting AlInGaNP. However making very small volumes of uniform semiconductor material from many elemental components is problematic as well as expensive. CEO and co-founder of Porotech Tongtong Zhu put it like this:
Porotech’s new class of porous GaN semiconductor material is now redefining what is possible – enabling the creation of efficient and bright native-red InGaN micro-LEDs and micro-displays
Tongtong Zhu CEO & co-founder, Porotech
Just how likely is this to happen? Over the summer Porotech have been busy adding three valuable components to the technology. In June a further £3M funding round was secured, led by Speedinvest. In August a key partnership was announced with major Chinese device manufacturer Jade Bird Display. Finally in September Porotech secured the services of former ARM executive Helen Adams as Chief Commercial Officer.
One mobile phone network provider used to claim that “the future’s bright, the future’s Orange”. Today for Porotech it seems “the future is bright, the future is red, green, blue, in fact any colour you want!”
Augmented Reality (AR) glasses are now looking remarkably stylish. Forget bulky Virtual Reality (VR) headsets and piratical Google Glass. Optoelectronics company Vuzix (Rochester, NY) has announced a pair of stereo vision glasses offering a head-up display (HUD) of the smartphone in your pocket. Or car. Or back home, actually.
CES 2021 (Jan 11-14), a consumer electronics show, handed Vuzix three CES2021 Innovation Awards for their Next Generation Smart Glasses (NGSG). Vuzix are saying we can expect the NGSG in the shops (pandemic permitting) summer 2021.
How did this happen?
Paul Travers founded Vuzix in 1997 with a desire not only to combine new technologies in innovative ways but also to provide solutions to customers’ problems. Vuzix has focused its AR product development on solving specific problems for specific customers. The Vuzix business model has therefore been B2B sales of wearable devices that: enable service engineers and technicians to follow instructions in manuals hands-free; allow clinicial experts to get a carer’s eye view of a patient; give advanced understanding to a surgical team awaiting the arrival of paramedic’s casualty.
Existing Vuzix products from the BLADE to the M4000 have exploited state-of-the art light sources, optical components and low power high performance microprocessors. Their latest NGSG exploits the latest microLED displays, Internet of Things chips and waveguide optics.
Probably the most significant new technology is the introduction of microLED light sources which offer high brightness, high spatial resolution displays with very low power consumption. Matching the colour detectors in the human eye, red green and blue microLED displays are combined in the glasses to project colour images to a focal plane in front of the wearer. MicroLED packages are indeed awesome things. Vuzix source their microLED components from Jade Bird Display (Shanghai, China). Incredibly, a monochrome display panel with 6000 DPI GaN diodes is smaller than a grain of rice! Jade Bird Display (JBD) claim their components are the worlds smallest VGA resolution displays. More information on Jade Bird Display components can be seen below.
So just how far can this technology go? how slim can the glasses’ frames be made and how big can the projected 3D images become?
Arguably the limit of the technology is set by the dimensions of the microLEDs themselves. JBD use GaN diodes in their displays that are tiny, just 4 microns in diameter. Microelectronic fabrication techniques can certainly make smaller devices. CMOS technology for example can produce structures on silicon wafers that are tens of nanometers in diameter. When a diode junction has to operate simply as a switch, subtle changes in material properties that result from their small size are not critical. The same isn’t true for the external optical properties of an LED. As the diameter of an LED gets smaller, its properties are increasingly determined by its edges rather than its bulk. Edge effects change the emission wavelength of the light and reduce the efficiency of the microLED device.
To really drive AR smart glasses and other display products forwards requires both increasing the resolution of microLED components and reducing their cost. This is challenging and requires improved test and inspection tools that can quickly detect defects on whole semiconductor wafers and analyse individual defects less than the size of a single pixel.
We will have to wait until later this year before we can get our hands on the latest AR glasses technology but microLED test and inspection instrumentation is available from Corbeau Innovation now, click below for product information.