Google Glass might be new on the scene, but wearable displays aren't unseen technology. Head-mounted displays have been projecting information into fighter pilot's eyeballs for years now, and we recently had the chance to get up close and personal with the latest and greatest systems out there.
The first thing we got to stick on was the Striker helmet, manufactured by BAE Systems for the Eurofighter Typhoon. The helmet qualifies as a head-mounted display because an image (or two images, strictly, as you'll see in a sec) gets projected onto the inside of the pilot's visor.
That imagery can be anything -- it can be just the information a pilot would get in a regular heads-up display, like heading, speed and altitude, or it can project an image of the outside world. What use is that? Well, if using regular day-time cameras, it allows the pilot to effectively have x-ray vision, seeing through his own plane.
Look down, and you see an image of the ground below you projected into your helmet -- exactly as if the plane had a glass floor. Look behind you, and it's as if there's no fuselage there. This effect can be repeated with different imagery, so (as long as the plane's fitted with the right gear), you can see thermal or night-vision imagery, or a 3-D representation of the terrain coming up.
There's even greater application for a helmet-mounted display when it comes to air-to-air combat, the very thing the Eurofigher was designed for. Prior to a helmet-mounted display, locking a missile onto an enemy fighter would normally involve turning your plane to point at the target, then unleashing your missile.
Now, all you have to do is look at the target -- which is marked in your helmet-mounted display with an icon -- pull the trigger, and the missile drops off the rail and turns itself to engage the target.
A sample of what you'd see projected onto the display
The display itself isn't the most complicated of systems -- two cathode-ray tubes, like you'd find in a old-skool TV, project one image each (one for each eye) onto the clear visor in front of the pilot's eyes, which allows the brain to combine the two images to create a proper binocular display.
The helmet is optically tracked by an IR camera in cockpit, so the computer always knows which way the pilot is looking. To enable the optical tracking, the helmet is littered with IR LEDs, giving the camera something to look for. The optical system is accurate, responsive, but also needs no bore-sighting (unlike the system on the Apache attack helicopter), so the pilot can jump into the plane and not have to worry about calibrating his helmet.
And, of course, the helmet provides the normal impact resistance you'd expect from a helmet, with a tough moulded outer shell that can withstand ejections from the cockpit at 600 knots. It's comfy too, with a custom-moulded inner shell for each pilot that's made for each individual's head.
The Striker system isn't the only one being worked on by BAE, however. The Q-Sight is a new innovation, designed to be cheaper and more modular than Striker. Rather than requiring a whole new helmet to be made, Q-Sight is a monocular that bolts onto the side of an existing aircrew system, putting a glass display in front of the pilot's eye in a manner not unlike Google Glass.
Unlike Google Glass, however, the monocular 'screen' is see-through, so the pilot can choose to focus either on the imagery displayed in the monocular, or on the world behind it. Same as in the Striker, any kind of imagery can be fed into the display, from camera feeds or aircraft symbology to stuff like virtual representations of flight hazards like power lines.
The first application for Q-Sight, in fact, is for door gunners rather than pilots. Gunners on the Navy's Merlin helicopters get .50-cal machine guns to use, but in order to look down the sights of the gun (and thus hit something, rather than firing in the general direction of "over there"), the gunners have to contort in fairly ridiculous positions round the already-cramped cabins.
Q-Sight helps with that, because it feeds the imagery from a thermal camera on the .50-cal straight into the door gunner's eyes. So, your fearless airborne dude can stay in one place, using the camera feed to accurately aim the machine gun, enabling him (or her) to do nifty things like shoot out the engine on a Somalian pirate's getaway boat.
That said, Q-Sight isn't just for military use. Heads-up displays are handy for any pilot, and something like Q-Sight can bring the previously expensive technology to pretty much anybody, as the cost is thousands rather than millions of pounds.
Of course, given a few years, consumer systems like Google Glass might usurp expensive tech like Q-Sight or Striker; though what advantages commercial systems have in terms of cheapness and hackability, they give up by being a wee bit fragile and unreliable.