Kopin’s ‘Elf’ Headset is Impressively Compact, More Than 3x the Pixels of Rift and Vive

Kopin is touting a new prototype VR headset featuring their 4K OLED ‘Lightning’ microdisplay that they say is made specifically for VR. At nearly half the size of other headsets, and made from lightweight materials, the device feels featherlight compared to VR products on the market today.

Update (8/19/17): Following my hands-on with Kopin’s ‘Elf’ headset at E3 where I got to look at the form-factor, I recently met with the company at the Silicon Valley offices of Goertek—Kopin’s manufacturing partner—to get a look inside a working demo of the headset.

Side and Weight

The functional Elf headset prototype was the same impressively small form-factor as I saw previously, featuring a pair of Kopin’s 1-inch ‘Lightning’ displays each with a 2,048 x 2,048 resolution and 120Hz refresh rate. The headset isn’t just significantly more compact than others—at just 220 grams it’s less than half the weight of the Rift and Vive (though at this point it’s lacking integrated audio, IPD adjustment, or positional tracking tech, which would require additional hardware and weight).

Connection

The headset connected to the host PC with DisplayPort and USB plugs which came together into a single thin cable that plugs into the headset with a USB-C connector. Kopin has developed an OpenVR driver to allow the headset to operate with SteamVR content.

Dark (for now)

The demo I was shown through the Elf prototype was a SteamVR game called InMind 2 VR. In the demo I was looking at models of brain neurons. The first thing I noticed when I put on the headset was how dark the image was. I could see fine, but it definitely seemed darker than it should be. When I asked Kopin about this they said that the display isn’t finalized and they expect to double the brightness by the time they are manufacturing them for sale.

Field of View

The second thing I noticed was the field of view which felt much closer to Google’s Daydream headsets than what you’d be used to with the Rift, Vive, or PSVR. Kopin said the prototype I was looking through was a 70 degree field of view, and that they’re working on developing different lenses to offer 80 and 100 degree fields of view (and I got to look through early versions of those lenses; more on that later). On the 70 degree prototype, the ‘binocular’ feeling (of having very noticeable dark circles around your field of view) was quite apparent. Despite the incredibly smooth and sharp image I was seeing, the low field of view is an immersion killer so it’s a good thing that Kopin is also developing lenses with a wider view.

Image Fidelity

With more than three times the pixels than the Rift and Vive (2,048 x 2,048 vs. 1,080 x 1,200), it looked stunningly sharp (pixel density in this case is getting an extra boost from the lower field of view too). Individual pixels are all but invisible, and I couldn’t make out any screen door effect. Since the 70 degree FoV lens isn’t Fresnel, I didn’t see any god ray artifacts (which are prevalent on the Rift and Vive), nor did I spot any chromatic aberration. I didn’t see any obvious mura issues which is good, but would want more time in the headset to be sure that there is none. Also, because this is a micro OLED display, the blacks were very deep. However, I didn’t get a chance to see the right scene to assess whether or not there was any black-smearing present.

Distortion and Correction

The Elf headset is made entirely to show off the display and lenses, so right now there’s no positional tracking tech built in. That means that in my demo the headset was only tracking rotation. The tracking felt fine and seemed exceptionally ‘smooth’ (likely thanks to the 120Hz refresh rate) though as I turned my head I noticed quite a bit of distortion warping the view around the periphery which seemed to be due to the lenses. Kopin says they are still working on the driver for the headset and tweaking the distortion correction; they seem confident that once the lenses and driver are finalized they’ll be able to eliminate the warping.

The Cost of a Wider Field of View

I also got to see prototype versions of Kopin’s 80 and 100 degree field of view lenses (backed by the same Lightning display) which were hooked up to a test board rather than built into a headset. The 80 degree lens was a two-element Fresnel and was much brighter than the 70 degree or 100 degree. It was clear that the field of view on the 80 was wider, but since it wasn’t hooked up to a headset with headtracking, it was difficult to get a good sense for how immersive it could feel.

The 100 degree lens was a two-element non-Fresnel and it was dark like the 70 degree lens. Although the lens itself may provide a 100 degree field of view, at that field of view you can see the edges of the display which, in my opinion, is less immersive than having a smaller field of view where you can’t see the edges of the display.

Kopin plans to develop larger displays in the future, which could mean a larger field of view without visible edges, but they won’t be ready for several years yet. Given that, Kopin’s 80 degree field of view option seems to be the best sweet spot presently for immersion and image fidelity. The big question will be: to what extent are consumers willing to trade field of view for image fidelity?

Elf is a Pitch, Not a Product

One important thing to remember about all of the above is that Elf headset is not going to become a product, it’s simply a pitch for Kopin’s VR microdisplays and Goertek’s manufacturing capabilities. The company’s hope is that a consumer electronics company will want to produce a product based on the Lightning display, and the Elf headset is the demo to sell them on the form-factor that it enables. Goertek says that the companies are “actively marketing” the Elf headset to potential consumer electronics companies. That means that an end product containing Kopin’s Lightning display might end up looking quite a bit different than the Elf headset today. In fact, although Elf is tethered, Kopin says that the foundation of the headset is also suitable for all-in-one mobile VR headsets.

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The original article continues below, which speaks to Kopin’s long term plans for developing VR displays (including those of higher resolution and large size), and the microdisplay vs. traditional approach to VR displays.

Original Article (6/14/17): Kopin is a publicly traded display manufacturer that was founded in 1984. With the massive buzz generated by VR, the firm has developed a roadmap for manufacturing displays specifically for VR headsets. Microdisplays by their nature are small and incredibly pixel dense, and also capable of high refresh rates.

The first microdisplay that Kopin is positioning for VR is what they’re calling ‘Lightning’, a 1-inch display with 2,048 x 2,048 per-eye resolution and running at a whopping 120Hz. With the Rift and Vive using displays of 1,080 x 1,200 pixels, Kopin’s Lightning display has just over 3.2 times as many pixels, and runs substantially faster than the 90Hz refresh rate of those headsets.

The tiny size of the microdisplay also brings another advantage: the potential for a much shorter focal length. Consumer VR headsets on the market are all roughly the same bulk size, not because we can’t design smaller enclosures, but because the physics of light requires that the displays be a certain distance from the lenses in order to present a focused image to the user’s eye. A smaller image allows for a shorter focal length, which means the displays don’t need to be as far from the lenses, potentially resulting in a much more compact headset.

Kopin has worked with Chinese ODM Goertek to develop a prototype VR headset that employs their Lightning microdisplay. The result is an incredibly compact and lightweight device that is an absolute joy to wear compared to the bulk of today’s consumer headsets.

I got to handle and wear a functional prototype at E3 2017, but unfortunately I didn’t actually get to see VR content through it since, according to the company, the only computer the company had on hand that was cooperating with the demands of driving a custom 4,096 x 2,048 resolution across both displays at 120Hz had to be shipped off to CES Asia (another conference which is also running this week). I expect to meet with Kopin again in the near future to see content running on the prototype headset; for now I can only talk about the form factor.

Compared to the consumer headsets on the market today, even the very lightest among them (like Gear VR and Daydream View) the Kopin prototype headset feels feather-light (note that it was missing a small driver-board for the displays which would add a slight bit to the weight). A single flexible strap that goes around the back of your head holds the device on your face with ease, no top strap required. The shell was made from a thin and extremely lightweight plastic. It was rigid, but it’s unclear to me if the durability of this material is enough to stand up to consumer usage; they may need to shift to a thicker or more durable material which could push the weight up some.

In photos alone it’s hard to appreciate how much smaller the Kopin headset is than others, but it feels much closer to the size and weight of a pair of ski goggles; it hugs close around your eyes without taking over so much of your face. It’s not nearly as ‘deep’ either, meaning it doesn’t jut out so far from your face. The slender profile compounds with the light weight since the leverage is not nearly as great as it would be with a bigger enclosure sticking further out from your face.

If and when most immersive VR headsets achieve this form factor, it’s going to make a massive difference in comfort and ease-of-use for VR.

Continued on Page 2: Microdisplay Tradeoffs »