The nVisor SX, developed and marketed by NVIS, is a high-end head-mounted display. It has a maximum resolution of 1280x1024 pixels, and costs about $24,000.

At first blush, using a pair of glasses or a helmet with one screen for each of eye appears to be an almost ideal solution for creating a real 3D effect. After all, each eye gets its own image.

The image created by the small displays is transmitted to the eye using a very complex optical system, which NVIS calls "Pancake Optics".

At first, such head mounted displays (HMDs) offered only very low resolutions; they were usually attached to helmets, and gave rise to the name "VR-helmets." The proximity of the displays to the eyes also caused problems if used for longer periods at a time, causing fatigue. Yet over the years, the technology has continually been refined, and nowadays HMDs support resolutions of up to 1280x1024 pixels.

Although HMDs allow for very good 3D presentation, they are still limited to a few professional applications, as their use in conjunction with a standard PC workstation is rather limited. However, HMDs are almost ideal for presentations, as the viewer can completely immerse himself in the 3D world. At the same time, this is also the technology's greatest limitation: if the user has to take care of other tasks at the same time, HMDs are not a suitable solution. Imagine, for example, a case in which an engineer has to enter input into a machine using the keyboard to adapt a simulation. A doctor of medicine will also be hampered by an HMD if he has to deal with other challenges such as attending to a patient or overseeing an operation at the same time. The HMD would have to constantly be removed and replaced.

The US Navy uses HMDs in their parachute trainer at the Naval Air Base in Pensacola

The XL100A HMD by Keo supports resolutions up to 1024x768.

As stated above, HMDs are ideal for simulations or presentations. They block out the surrounding world, allowing for complete immersion into the virtual setting. In principle, HMDs would also be ideal for gaming on the PC - if their prices ever drop enough to become affordable.