It’s been just over a year since Valve released Index, their flagship VR system, and it’s worth looking back at this GitHub repository as a fine example of how to provide supporting materials to a hacker-friendly hardware design. The image above shows off one of the hacker-friendly design elements: an empty space behind the visor, with a USB port off to the right, that exists for no reason other than to make it easier to mount and plug in whatever one might come up with. There’s more to it than that, however. If one wishes to provide supporting materials for a hardware design, one could certainly do worse than emulate Valve’s example.
The hardware repository contains not just CAD models of mod-friendly hardware pieces (both in high-resolution STEP models as well as STL files) but also 3D models of the sensor zones, so modders can ensure they avoid occluding any sensors with their creations. Examples are great, and one provided by Valve is the Booster; a hand controller add-on providing extra comfort for people with large hands or long thumbs. The model also doubles as a reference for designing attachments that will not interfere with any of the tracking or touch-sensitive surfaces of the controllers.
Being hacker-friendly doesn’t mean the hardware has no warranty, but it does mean that there is concrete guidance on what does or doesn’t risk voiding it. In the case of the Index hardware, the guidance is simple: “Anything that requires a T5 or smaller is not user serviceable.”
Want to see what exactly is inside the $500 (headset only price) Valve Index VR headset that was released last summer? Take a look at this teardown by [Ilja Zegars]. Not only does [Ilja] pull the device apart, but he identifies each IC and takes care to point out some of the more unique hardware aspects like the fancy diffuser on the displays, and the unique multilayered lenses (which are much thinner than one might expect.)
[Ilja] is no stranger to headset hardware design, and in addition to all the eye candy of high-res photographs, provides some insightful commentary to help make sense of them. The “tracking webs” pulled from the headset are an interesting bit, each is a long run of flexible PCB that connects four tracking sensors for each side of the head-mounted display back to the main PCB. These sensors are basically IR photodiodes, and detect the regular laser sweeps emitted by the base stations of Valve’s lighthouse tracking technology. [Ilja] also gives us a good look at the rod and spring mechanisms seen above that adjust distance between the two screens.
VR headsets have been seeing new life for a few years now, and when it comes to head-mounted displays, the field of view (FOV) is one of the specs everyone’s keen to discover. Valve Software have published a highly technical yet accessibly-presented document that explains why Field of View (FOV) is a complex thing when it pertains to head-mounted displays. FOV is relatively simple when it comes to things such as cameras, but it gets much more complicated and hard to define or measure easily when it comes to using lenses to put images right up next to eyeballs.
The document goes into some useful detail about head-mounted displays in general, the design trade-offs, and naturally talks about the brand-new Valve Index VR headset in particular. The Index uses proprietary lenses combined with a slight outward cant to each eye’s display, and they explain precisely what benefits are gained from each design point. Eye relief (distance from eye to lens), lens shape and mounting (limiting how close the eye can physically get), and adjustability (because faces and eyes come in different configurations) all have a role to play. It’s a situation where every millimeter matters.
If there’s one main point Valve is trying to make with this document, it’s summed up as “it’s really hard to use a single number to effectively describe the field of view of an HMD.” They plan to publish additional information on the topics of modding as well as optics, so keep an eye out on their Valve Index Deep Dive publication list.