HoloFlex: A Flexible Smartphone with a Holographic Display

Queens Univesity's Holoflex bendable 3-D smartphone.
Photo: The Human Media Lab/Queen’s University

Based on how things have been going for the last few years, it seems like we're getting awfully close to hitting peak smartphone, where new phones have run out of ways to differentiate themselves besides being slightly faster or slimmer or brighter or whatever. We’ve almost forgotten what it’s like to see brand new phones with a fundamentally new and exciting technologies inside of them. Oh, you've got a fingerprint sensor that's under the screen now instead of under the bezel? Hooray.

Fortunately for tech lovers everywhere, the Queen’s University Human Media Lab in Canada is keeping busy reminding us that smartphone hardware really does have a future that's worth getting excited about. Their latest prototype is the HoloFlex, which runs Android Lollipop, includes a full HD screen, and is powered by a 1.5 GHz Qualcomm Snapdragon 810 processor with a dedicated GPU and 2GB of RAM.

And did we mention that you can bend it, and that it has a holographic lightfield display that can project glasses-free 3-D images to multiple users simultaneously? Because it’s got that stuff going for it, too.

Let's take a look at the display first. It's based on a FOLED (flexible OLED) screen with a resolution of 1920 x 1080 pixels (403 dpi) and a touch layer. On top of that is a 3-D printed flexible lens array made up of 16,640 half-dome shaped droplets in a 160 x 104 hexagonal matrix. Each lens projects the 12 pixel-wide circular area directly underneath it out into space, and each of those approximately 80 pixel image blocks contains information about the entire scene from a virtual camera position that's unique to the position of the lens. Essentially, each of those 16,640 lenses is projecting a slightly different view of the same scene, and all of those image blocks together represent 3-D information about the full scene over a field of view of about 35 degrees.

We keep using the word “information” here because this is a lightfield display, which renders images holographically. A hologram looks three dimensional because the lightfield that it’s based on doesn't just include information about where a pixel is on the x-y plane as a traditional display does, but also information about the angle of light rays. In other words, it’s reconstruction of all of the information about a scene, not just a snapshot of a scene from one single perspective. You can replicate this effect in software, calculating the lightfield that an arbitrary scene would create. Then your array of image blocks and lens droplets can distribute the light rays across multiple perspectives simultaneously to generate a hologram of whatever you want. 

The upshot of this is that HoloFlex can transform software models into lightfield display-based holograms, resulting in images that have depth and exhibit motion parallax and can be viewed from multiple perspectives by multiple users. The resolution isn't great (just 160 x 104), but no weird glasses or tracking is necessary. I'm sure the (2-D) video doesn't do the effect justice.

Now that you’ve got this awesome holographic smartphone display with a useful z-axis, you need some way of interacting with it. Why use something clunky like gestures when, thanks to flexible electronics, you could just bend the entire phone itself? The left side of the phone is rigid, while the rest of it acts like a spring, providing passive haptic feedback for intuitive control over the z-dimension. And as a side benefit, bending the phone makes it the holograms seem even more three dimensional, as they can “jump” across the display.

This is by far one of the smallest and most mobile lightfield displays we've ever seen, and both of these demos (editing of a model for 3-D printing, and gaming) actually seem like useful applications for the technology rather than just novelties. The Queens inventors don't make any mention of commercialization, but it’s worth noting that the only bit of hardware that isn't commercially available (or close to it) is the microlens array, and that’s 3-D printed. Does this mean that we're likely to see smartphones with holographic displays on the market sometime soon? Probably not. But at some point, maybe. At the very least, it’s things like this that could mean that peak smartphone hasn’t quite hit yet.

HoloFlex will be presented next week at ACM CHI 2016 in San Jose, Calif.

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