This article needs to be updated.(June 2016)
A virtual reality headset is a head-mounted device that provides virtual reality for the wearer. VR headsets are widely used with computer games but they are also used in other applications, including simulators and trainers. They comprise a stereoscopic head-mounted display (providing separate images for each eye), stereo sound, and head motion tracking sensors (which may include gyroscopes, accelerometers, structured light systems, etc.). Some VR headsets also have eye tracking sensors and gaming controllers.
The Sega VR, announced in 1991 and seen in early 1993 at the Winter CES, was never released. An early VR headset, the Forte VFX1, was announced at CES in 1994. The VFX-1 has stereoscopic displays, 3-axis head-tracking, and stereo headphones. Sony, another pioneer, released the Glasstron in 1997, which has an optional positional sensor, allowing the wearer to view the surroundings, with the perspective moving as his head moves, giving a deep sense of immersion. These VR headsets gave MechWarrior 2 players a new visual perspective of seeing the battlefield from inside the cockpit of their craft. However, these early headsets failed commercially due to their limited technology and were described by John Carmack as like "looking through toilet paper tubes".
In 2012, a crowdfunding campaign began for a VR headset known as Oculus Rift; the project was led by several prominent video game developers, including John Carmack who later became the company's CTO. In March 2014, the project's parent company Oculus VR was acquired by Facebook for US$2 billion. The final consumer-oriented release of Oculus Rift began shipping on 28 March 2016.
In March 2014, Sony demonstrated a prototype headset for PlayStation 4, which was later named PlayStation VR. In 2014, Valve Corporation demonstrated some headset prototypes, which lead to a partnership with HTC to produce the Vive, which focuses on "room scale" VR environments that users can naturally navigate within and interact with. The Vive was released in April 2016 and PlayStation VR in October 2016.
Virtual reality headsets and viewers have also been designed for smartphones. Unlike headsets with integrated displays, these units are essentially enclosures which a smartphone can be inserted into. VR content is viewed from the screen of the device itself through lenses acting as a stereoscope, rather than using dedicated internal displays. Google released a series of specifications and associated DIY kits for virtual reality viewers known as Google Cardboard; these viewers are capable of being constructed using low-cost materials, such as cardboard (hence the naming).
Samsung Electronics partnered with Oculus VR to co-develop the Samsung Gear VR (which is only compatible with recent Samsung Galaxy devices), while LG Electronics developed a headset with dedicated displays for its LG G5 smartphone known as LG 360 VR.
Asian hardware manufacturers like Xion and Kolke have developed inexpensive virtual reality headsets. In late April 2017, the Chinese company Tencent announced it was preparing to launch its virtual reality headset that year.
Virtual reality headsets have significantly higher requirements for latency—the time it takes from a change in input to have a visual effect—than ordinary video games. If the system is too sluggish to react to head movement, then it can cause the user to experience virtual reality sickness, a kind of motion sickness. According to a Valve engineer, the ideal latency would be 7-15 milliseconds. A major component of this latency is the refresh rate of the display, which has driven the adoption of displays with a refresh rate from 90 Hz (Oculus Rift and HTC Vive) to 120 Hz (PlayStation VR).
The graphics processing unit (GPU) also needs to be more powerful to render frames more frequently. Oculus cited the limited processing power of Xbox One and PlayStation 4 as the reason why they are targeting the PC gaming market with their first devices.
Resolution and display quality
There are different optics and visual qualities that will affect how the individual views the image quality and how they experience the virtual world. The image will appear clearly due to the display resolution, optic quality, refresh rate, and the field of view.
Because virtual reality headsets stretch a single display across a wide field of view (up to 110° for some devices according to manufacturers), the magnification factor makes flaws in display technology much more apparent. One issue is the so-called screen-door effect, where the gaps between rows and columns of pixels become visible, kind of like looking through a screen door. This was especially noticeable in earlier prototypes and development kits, which had lower resolutions than the retail versions.
The lenses of the headset are responsible for mapping the up-close display to a wide field of view, while also providing a more comfortable distant point of focus. One challenge with this is providing consistency of focus: because eyes are free to turn within the headset, it's important to avoid having to refocus to prevent eye strain.
Many manufacturing companies have used a variety of lenses, but many have used the Fresnel lenses. The lenses do not use multiple pieces of material in their lenses like other lenses, but the lens will be broken down into sections, allowing the individual to have a wider range of view. The issue seen with the lens consists of seeing the ridges of the lenses when the headset is not properly aligned on the head.
The lenses can also be adjusted dynamically to account for a user's eyeglass prescription, so that the user can use the headset without corrective eyeglasses.
Virtual Reality was used by Nintendo's Wii game console by having the player use a controller to interact with the game of their choice, often being sports games. Soon after the release of Nintendo's Wii, Xbox released a full body reading system called "Kinect" and PlayStation released a similar virtual reality device named "PlayStation Move." These gaming devices use virtual reality to control avatars within a game, where the player's movements are copied by the avatar to complete the game. This means that the player is not truly engaged in the virtual reality world.
Uses in various fields
Virtual reality headsets are being currently used as a means to train medical students for surgery. It allows them to perform essential procedures in a virtual, controlled environment. Students perform surgeries on virtual patients, which allows them to acquire the skills needed to perform surgeries on real patients. It also allows the students to revisit the surgeries from the perspective of the lead surgeon.
Traditionally, students had to participate in surgeries and often they would miss essential parts. Now, with the use of VR headsets, students can watch surgical procedures from the perspective of the lead surgeon without missing essential parts. Students can also pause, rewind, and fast forward surgeries. They also can perfect their techniques in a real-time simulation in a risk free environment. 
The virtual reality headset helps with therapy. People with mental health and addiction issues use therapy by virtual reality headsets to help get over these issues. The Virtual Reality Headset helped patients get over fear, anxiety, panic, and acrophobia. One patient was exposed to a virtual spider for 50 minutes a day over the course of a 12 week period. The Virtual Reality Headset also was used for exercising. Many exercising programs and sports games were created. When a patient is going through therapy, the patient has control over the exposure they have. During the exposure, the patients thoughts, feelings, muscle tension, and heart rate are all observed. Virtual Reality has psychological principles from cognitive-behavioral therapies, neurobiology, neurophysiology, existentialism, and psycho dynamic conceptualizations and knowledge in behavioral neuroscience. The Virtual Reality Headset helped patients get some emotional relief from their day-to-day medications.
Virtual reality headsets have been used for training United States soldiers of the army, air-force, and navy. It is a particularly useful tool for training soldiers without putting them in harm's way.
The virtual reality headset allows the military personnel to interact with virtual reality people to make it feel real. They can talk to one another and do varying actions to make the virtual reality world feel like they are actually in that situation. There are also disadvantages and advantages when military personnel use the headset. The disadvantage is the headset is made for an indoor area, with a cool environment, and away from any heat, so when military personnel have just the headset on, no military equipment, it is not like their basic training. The advantages consist of repeating the situations multiple times and the cost of having the headset is less, due to no military equipment being needed.
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