# Valve Index

The Valve Index is a consumer virtual reality headset created and manufactured by Valve. Announced on April 30, 2019, the headset was released on June 28 of the same year. The Index is a second-generation headset and the first to be fully manufactured by Valve. Half-Life: Alyx is bundled with the headset.

## Development

The Valve Index is Valve's first virtual reality headset developed and manufactured in-house, and was developed as the primary hardware for Valve's upcoming virtual reality games, starting with the launch of Half-Life: Alyx. Development on a completely first party headset started sometime around 2015 according to interviews with staff, before the release of their Vive headset with HTC. In February 2021, Valve registered patents for a new VR headset, describing the improvements over the previous model.

## Release

The Valve Index sold an estimated 149,000 sets in 2019. 103,000 were in the fourth quarter following the announcement of Valve's flagship VR game, Half-Life: Alyx, which was made free to Index owners. The sudden demand caused the unit to be sold out in all 31 countries except Japan in January 2020. While Valve had anticipated supply for many of those that had ordered the Index in time for the March 2020 release of Half-Life: Alyx, the COVID-19 pandemic slowed production, which left Valve with a reduced number of units available on the release date. As of January 2025, 13.2% of the VR units connected to Steam are Valve Index sets.

## Technical specifications
### Display

The headset features dual 1440 x 1600 LCDs with full RGB per pixel and ultra-low persistence global backlight illumination (0.330 ms at 144 Hz). It includes dual-element canted Fresnel lenses and provides a combined resolution of 2880 x 1600. The panels are full RGB and support refresh rates of 80, 90, 120, or 144 Hz. The estimated field of view is 108°. The panels and lenses can be adjusted horizontally to change the user's inter-pupillary distance (IPD) using a physical slider beneath the displays, with an IPD adjustment range of 58 to 70 mm.

### Tracking

The headset and controllers both use lighthouse tracking systems, while retaining full compatibility with all previous HTC Vive base stations, using SteamVR.
The Valve Index utilizes Valve’s Lighthouse 2.0 tracking system, which involves external base stations to establish a 3D tracking environment. These base stations are small, rectangular units placed around the room that emit non-visible infrared light and laser patterns. The headset and controllers, equipped with sensors, detect these signals to determine their position and orientation.
Each base station includes two rapidly spinning laser emitters that project a sweeping pattern of lasers across the room. Unlike the Lighthouse 1.0, which used an infrared Sync Blinker for synchronization, Lighthouse 2.0 employs a more refined synchronization mechanism integrated into the laser system itself. The sensors on the headset and controllers detect the laser beams to determine their exact positions relative to the base stations. Typically, two base stations are used to ensure comprehensive coverage and minimize occlusion, though additional base stations can be added to extend the tracking range.
Although the Valve Index uses external base stations, the tracking system is considered inside-out because the tracking sensors are mounted on the tracked devices themselves—the headset and controllers. These sensors process the tracking information internally, which differentiates it from traditional outside-in systems that use fixed cameras or sensors to monitor the tracked objects from outside.
In addition to the base stations, the Index’s headset and controllers feature Inertial Measurement Units (IMUs) that provide rapid updates on movement and orientation. The IMUs track motion at several hundred Hz, but are prone to drift. The Lighthouse system compensates for this drift by using the base stations’ lasers to provide a precise positional reference, integrating this data with the IMU information to maintain accurate tracking even during fast movements.
This combination of external base stations and internal sensors on the tracked devices ensures the Valve Index provides accurate and responsive tracking performance.

### Controls

The headset is intended to be used with the Valve Index Controllers—formerly known as the Knuckles Controllers—but is also backward compatible with the HTC Vive and HTC Vive Pro controllers. The Valve Index Controllers feature a thumbstick, touchpad, two face buttons, a menu button, a trigger, and an array of 87 sensors that track hand position, finger position, motion, and pressure to create an accurate representation of the user's hand in VR. Additionally, the controllers include an accelerometer for further measurements. In 2018, a tech demo called Moondust showcased the capabilities of an early version of the Knuckles.

### Audio

The Index includes "a pair of ultra near-field, full-range, off-ear (extra-aural) headphones", which use Balanced Mode Radiator (BMR) drivers to produce accurate and low-frequency sounds. The headset also has a built-in microphone.